EMF Pump

Can I use a sphere magnet when building an EMF PUMP? Glued onto the pulley. Thanks

Topic by papster   |  last reply

Steppers and EMF.? Answered

I have build this Bi-Polar stepper circuit and it works great on the bread board. I etch a board 3 times, 2 with heat transfer and 1 with photo resist. I use 2 completely separate power supplies but with the PCB's i think i am experiencing EMF or feed back. I am using an adjustable schmidt trigger for the clock. What happens is i can hardly get any rpm's, sometimes if the trigger is set just wright it will turn up fairly well, at that time if i try full step the stepper stops turning or will reverse sometimes, if i try ccw it may or may nor reverse and i may stay in what ever direction and any given time . Now at a slow rpm full step normally work's and cw/ccw may or may not work, also it can trigger the half or full step. Also i can disconnect one coil and the stepper will continue to turn, If i try that with the other coil the stepper will stop. So it looks like it is only running on one coil. Is that possible? Keep in mind i have bread boarded it and work's fine. Its just on the 3 pcb's that all this happens. As for the diodes it seams to work better with 1N4001's than 1N4148's I have checked every trace with an DMM and made sure they are going to the correct pins ect. I have tried different IC's L297 and L298 and steppers 2 different kinds and multiples of each. So i am thinking this is EMF, feedback, or a design problem. I have tried to eliminate most every thing i can think of. Comments?     

Question by WWC   |  last reply

EMF camp

Anyone else in the UK heading to EMF camp at the end of August ? https://www.emfcamp.org/ Steve

Topic by steveastrouk   |  last reply

protecting from EMF?

So i am working on some high power geophysical transmitters which are being damaged by back emf. can anyone help me with what would be the best way to protect the instrument from this. we are mainly blowing the switching IGBT's. the transmitter is supplied DC from a 30kw powersupply, feeding a set of IGBT's which are switched at a selected frequency usually 0.5 to 2hz at 50% duty cycle into a loop of wire ranging in resistance but usually around 1 ohm. we run this at up to 150A at 150V and our loads can be very inductive, usually 300mx300m 25sqmm copper wire. im thinking diodes or caps for a bit of protection. im open to any ideas

Question by benmerlingeo   |  last reply

EMF [electromagnetic field] shield fabric?

Does anyone know how to make EMF [electromagnetic field] shield fabric?

Question by lindaoak   |  last reply

How can I generate a power source via EMF waves around us without using any other power source?

Tell simply and more efficent way while dealing with it. Also it must work and practically available as well as possible.

Question by asim164   |  last reply

How could I build an EMF pump, or EMF generator to generate levels of electromagnetic field in a small room? Answered

As a lot of people know, electromagnetic fields have been associated with hauntings, and some theorize that entities use these as power sources to affect things on our plane. I've seen these things being built and sold on the internet, even being run with a 9V battery and emitting 300 gauss in an entire small room. How could I go about building one of these units?

Question by RUSHAVED   |  last reply

How to protect our house from EMF ( Electromagnetic Field )....Pls. tell me any idea...?

Dear Frnds, i, sameer gurav, mobile tower company installing mobile tower top on my residence, i read its radiation is very dangerous effects...so pls help to protect from this radiation. Tell me any idea how to protect my home from radiation (Mobile Tower Radiation). Thanks, Sameer

Question by sameer.gurav   |  last reply


Hello all My friends and I are interested in some fun ghost-busting as a science experiment. We wanted to ask if there was a way to create a cost effective EMF meter to detect paranormal activity. Thanks for your help!

Topic by powerphysician   |  last reply

First project completed...now let's expand it!

My wife is interested in ghost hunting shows like TAPS and Ghost Hunters International. She even joined a local Paranomal Society. The first thing she wanted to buy was an EMF detector for a whopping $175. Now, I don't believe in ghosts, but I support my wife, so instead of buying her an OTS EMF detector, I decided to build her this one. Thanks Computergeek! Oddly, the first thing that popped into my head when I finished building the Arduino EMF detector was a quote from Keano Reeves from Point Break, "I caught my first tube today....Sir." It's appropriate though, in the sense that he was just getting started in the bank robbery investigations. I'm pretty happy with this build...I had a couple of issues in hardware and code that I was able to troubleshoot myself. And it all works! So this was pretty easy, even for a newbie. Now, what I want to do is add a data logger that records values to flash memory. You can probably see where I'm going with this (as a non-believer). If you remove the human element from the situation, is there still paranomal activity? Or put another way, if a tree falls down in the middle of the forest and no one is around to hear it...does it still make noise? If anyone has any ideas, tips, or suggesstions, I'd love to hear them. Thanks for a great online community! LorienD  

Topic by LorienD 

over 90W of flyback (back EMF) energy? how to dissipate it? Answered

Continuing my work on the flyback driver, I am investigating methods and practices to protect my MOSFETs from overvoltage conditions. I have measured peaks of as much as 350V across a 250V MOSFET while drawing an arc, and it does not matter what I do it seems like I simply cannot limit the back EMF transients to <250V. I am really impressed by the rugged nature of these MOSFETs, although I have popped quite a few of them. Seeing that they are being bombarded with almost 400V transients, it is a wonder they survive as long as they do. When I added a medium sized reverse biased zener diode in series with a 10 ohm 1 watt resistor, both went up in smoke, especially the resistor! The zener diode survived. I also tried a much larger screw mounted 30V zener diode w/o the resistor and it reached much over 100 degrees C after only a few seconds and I had very little output on the secondary. Judging by how quickly a 10 watt resistor heats up I assume that the back EMF very low impedance and has to be over 90W average!!! I'll need to try to use the integration feature on my scope to measure the average power dissipation accurately. In none of the configurations involving a resistor did I see the voltage clamped any lower than before. :(

Question by -max-   |  last reply

Trying to create a circuit to allow me to adjust the frequency of AC power

I'm trying to design an EM field generator with adjustable frequency. I've got most of it figured out, but I can't seem to find anything about how to create adjustable frequency AC power. I've got two designs I'm working on, one that is DC powered and one that is AC powered, but the best I can do on either ends up with a 60Hz EM field. I'm looking for adjustable frequency, ideally from 0.1Hz to 50kHz, although I'll be pretty happy to even get any range of frequencies at all. The range from 0.1Hz to 500Hz is the most useful and interesting in particular for my purposes, but any help on figuring this out at all would be much appreciated.

Topic by PsychoHazard   |  last reply

Has anyone any advice on building a Faraday cage for VHF - 20GHz or higher?

Hi, I've found lots on the 'net about building Faraday cages, but most of these are a couple of years old and targeted at lower frequencies up to around around the 2.4GHz range. I'm looking at making a Faraday cage for a room, to shield against a recent phone tower upgrade with transmissions now in the 19GHz range. (I've seen some other towers, fortunately not near me, recently approved for transmissions at 38GHz.) From what I've read so far, I'd need about 20 layers of heavy duty alfoil to come close to getting effective shielding, or wire with holes less than 7.5mm wide, which is going to be pretty tricky. Just wondering if anyone's tackled this problem before and, if so, how?

Question by powerup   |  last reply

HELP: Measuring power density from cellphone tower.

I am working on a project to measure the power density from cell tower. Most projects I saw involve expensive antenna and also a spectrum analyser which is too costly. I came across showing ppl fabricating a target single band microstrip passing through a RF Detector circuit. I think chip like AD8318 could handle it?? But how am I gonna filter if were to use an antenna with range of 200MHz to 2GHz eg. (https://www.sparkfun.com/products/8347) to measure a specific GSM band like 900/1800 MHz from the cell tower? I need help on the filtering and RF detector circuit part!!The closest resemblance to my proposed system: https://www.favoriot.com/category/how-to/

Topic by StudD   |  last reply

what is the EMF AND torque equation for BLDC motor?

How to calculate BLDC equation paramaeters?

Question by vickyraja   |  last reply

How test microchip used in pets?

RE: microchips used in pets...how can you test/find if EMF, WIFI, electric fences, cordless phones, cell phones etc. could activate the chips?  Cancerous tumors recently formed around chips in 2 dogs (March 2010-both dogs have died & in lab shrew mouse 2009 & in other dogs 2007).  No research found on this...only large corporations stating how safe chips are.  Does anyone know?

Question by rockmason   |  last reply

Capacitor charger

I want to build a fast simple capacitor charger with minimal components. i was going to builda dc to dc converter. but then came across this picture from here i am going to replace the switch with a 555 timer and transistor . does any body know if this circuit is any good or has any body built it

Topic by chrischavez   |  last reply

Electromagnet back emf (CEMF), need advice Answered

So the specifications of the electromagnet : 24v 0.2Amp Holding force 500lb The input is 24v, .  once the voltage is disconnected the Back EMF will occur, at that instant there still is a magnetic field which collapses very fast, in collapsing it 'cuts' the coil at high speed and the higher the 'Q' coil the more voltage is 'generated'. I imagine that my electromagnet that can lift 500lb with 24v will generate a huge CEMF. So my question is, approximately how much Cemf should I expect and could I use it to recharge my batteries? Let's say I switch it on for 1sec than switch it off. There are techniques for back emf suppression, http://www.progeny.co.uk/Back-EMF-Suppression.aspx I would like to redirect it, transform it to make it usable and recharge my batteries with it. If I manage to do it, will I get at least as much power from the cemf in order to be able to recharge my batteries (or capacitator)

Question by Maxc13   |  last reply

about programming emf (Electromagnetic Field) detector

Excuse me, I would like to inquire about emf detector. I saw one of the projects in makezine.com make emf with arduino, with LED bargraph. but here I replaced it with a small audio (8 Ohm), but why not come up with the perfect voice? This is my remake program   if(val >= 1){                    val = constrain(val, 1, senseLimit);     val = map(val, 1, senseLimit, 1, 1023);      total -= readings[index];                  readings[index] = val;           total += readings[index];                  index = (index + 1);                        if (index >= NUMREADINGS)                    index = 0;                               average = total / NUMREADINGS;              if (average > 50){                tone(10, 50, 100); delay(1000);     }     if (average > 150){              tone(10, 50, 200); delay(1000);    } if (average > 250){ tone(10,50,300); delay(1000);     } if (average > 350){ tone(10,50,400); delay(1000);     } if (average > 450){ tone(10,50,500); delay(1000);     } if (average > 550){ tone(10,50,600); delay(1000);     } if (average > 650){ tone(10,50,700); delay(1000);     } if (average > 750){ tone(100,50,800); delay(1000);     }         Serial.println(average);     delay(updateTime);   } } void tone(long duration, int freq) { duration *= 1000; int period = (1.0 / freq) * 1000000; long elapsed_time = 0; while (elapsed_time < duration) { digitalWrite(pinSpeaker,HIGH); delayMicroseconds(period / 2); digitalWrite(pinSpeaker, LOW); delayMicroseconds(period / 2); elapsed_time += (period);   } } please answer. Thank's.

Question by dzikriyana   |  last reply


HI, I would like to know if there is a solenoid that will retract when power in one direction is applied to it and when the current is reversed, the solenoid sticks out again. THANX VERY MUCH IN ADVANCE, i look forward to reading your answer. Ahmad

Question by in06khattab   |  last reply

So, EMF blocking Stickers, Pendants or Death-Crystals? Answered

Uh, how to start with this one... Local health store started carrying the latest line of emf blocking stickers and pendants. At first I thought good grief, if people are that gullible as to not look into the science behind they perhaps deserve to have there money parted from them. Several weeks later though, a symposium was booked in the local convention hall. I was surprised to learn how many people actually went to this, and were indeed parted with a fair chunk of change. If you look into to it there are numerous if not hundreds of these anti-emf scams abound on the internet all claiming only theirs works... That alone would send my spidey senses tingling. I really don't want to get in to the science behind why this is a scam, and would appreciate answers from people who know what they are talking about rather then those have been duped. Moving on... I am afraid the owner of the health store is going to get slammed on this one eventually. Normally I would say the owner of the store has a good head on her shoulders with an excellent BS sensor. Not so much, this time around. Guess my question would be how to inform her of why its a scam with out her eyes rolling into the back of her head. "Had a friend go the symposium for kicks, "she has a doctorate in bio-engineering, health science and is pursing her latest degree in occupation health sciences." To her shock and delight it was simple for her to see through the scam, but she had to admit his did provide a technical sounding argument, mixing truth with techno babble, that perhaps someone with an understanding of only layman’s terms could be persuaded by. Oh, what to do...

Question by iminthebathroom   |  last reply

What exactly do light-sensitive elements react to? Answered

I had an old (about 1970s) large power transistor (I think it was a field-effect one, but I am not completely sure...). Knowing it is supposed to be light-sensitive I took the top of the case off, and it has a small EMF between the collector and emitter when exposed to light. But the EMF from directly under  electroluminescent lamps in the school corridor is about 10 times smaller than from lying on a sun-lit windowsill. So light-intensity can't be the only thing the EMF depends on... But what is the other thing?  PS It can't be UV, because well... we have glass in the windows at school, although it risks to get broken, as there is a football cup at the moment.

Question by gruffalo child   |  last reply

555 triggered by a switch and thyrister problem!! PLEASE HELP!!

Hi, I have a problem because a switch is working as a reset switch for the solenoid as well as a tension release mechanism for the pulley. The thyristor is also triggering the 555 chip (monostable). Do you guys have a solution, please do not tell me to have 2 switches for the tension release as well as the reset for the solenoid circuit. PLEASE SEE MY ATTACHED PICTURE AND MY VIDEO ON YOUTUBE EXPLAINING MY PROBLEM FURTHER!! http://www.youtube.com/watch?v=akqatPnyV04 Ahmad

Question by in06khattab   |  last reply

What metals (Copper) or a Silver oxide-Copper solution on Mold with EMF from High voltage spark gap should I use for a project?

I am having problems deciding if I should use diluted silver nitrate on agar (Cocoa agar with sugars) or just add silver oxide and copper or copper powder to plates with Pencillum I growing on them then expose them into an aluminum sheet to fit three plates.This will determine if EMF alone (30 or 60 minutes, etc) or combined with small amounts of copper and silver (II) oxide mix or copper would prevent or kill spores? Alone EMF from high voltage may just inhibit growth but the silver copper mix may totally kill them!!It difficult since a correct dosage of this silver-copper mix must be used or copper. If it is too high it will prevent any growth before the EMF can have any effect. So maybe I need to dose it with 1g 5g and 2.5 g silver copper and see which one has modernate growth inhbition effects. Each test will be done together to save time.

Question by SHOE0007 

Accessing SD memory on data logging shield

Hey again, I finished my first project recently and was looking to expand on the design. It's an EMF detector (https://www.instructables.com/community/First-project-completednow-lets-expand-it/) and it's working great. Now, I want to add memory and a USB charger to turn it into an self-contained EMF data logger. The project looks easy enough, but I have a question that I wasn't able to find answers for. Here's the question: Can the memory installed on the data logging shield be accessed through the Arduino USB port? On my cell phone, whenever I plug the USB into my laptop, it connects as a drive. I'd like to do the same thing with the EMF data logger. Or will I just have to remove the SD card every time I want to extract data from it? Thanks LorienD

Topic by LorienD   |  last reply

Regen Braking Motor Controller

Good morning.... Quick question regarding motor controllers with the facility of regen braking..... For a project of mine I am creating an EV (with a dune buggy chassis), which needs a system to recharge the batteries when been driven or 'towed' by an external force. I've been looking at a 4QD motor controller, which has the regen braking system already built in. My idea is to use the back EMF to charge the batteries. This in theory is quite similar to regen braking, having done a bit of research, and also with some info from the 4QD site itself. I know that if the back EMF is to great, I risk damaging the motor controller. But if there was a way to regulate the back EMF (either by controlling the speed it is been externally driven or with use of electronic circuitry), could I essentially recharge the batteries using this motor controller???! Thanks in advance, Dave

Topic by D__Humphreys   |  last reply

Electromagnet using permanent magnets

Hi All, I'm attempting to make a very small strong electromagnet using permanent rare earth magnets. I want to boost the magnetic field and increase the magnetic force. The magnets are 10mm in length by 5mm in radius. I have 0.4mm2 enamelled solenoid wire for the winding. My questions are, Is it possible to increase the force of a permenent  magnet? Will the induced flux into the magnet compile the force or will the EMF have to be greater to see an effect? Will paralleling two windings make the EMF stronger? As the magnets are small I have limited room to wrap windings so is there a more effective method? Any help would be great!

Topic by JimmyM5   |  last reply

Is it possible to make an inductive grounder?

I'm looking for people who are familiar with Inductive Charging. Would it be possible to do the same thing, but with grounding?  Say like taking your own personal body charge and discharging it into the ground via field? I'm just thinking of grounding yourself for working around electronics in a way that can keep you really mobile while doing it.   Or maybe even helping to block EMF.

Topic by technicallyartistic   |  last reply

What flyback diode should I use for my spark gap transmitter?

The power is a 12V car battery ( I think 20A) and I have a car ignition coil with an output of 45kV.  I want to use a 555 for the interrupter and wondering how to size the flyback diode to protect the circuit.  I have limited knowledge of circuitry and trying not to electrocute myself!thanks!

Question by dennis.ostrem.5 

pwm arduino

I have a couple questions about driving motors from the arduino (I have a boarduino) - First off, these motors are from various walkmans and I think each one is rated for 1.7 volts. - If I need a transistor, can i use a 2n3904 (since these arn't giant motors) - How do I protect against the emf? The motors need to work going either way (clockwise or counter clockwise) - How would you program it so that the motor can go either forward or backwards?

Topic by guyfrom7up   |  last reply

I would like 5 environmental sensors linked to an Arduino then to my smart phone or an Ipad. Is this possible?

My idea is to have a radiation detector, emf detector, static ion detector, radio wave detector, and temperature gauge going to an Arduino, and it reading all 5 detectors at the same time, giving simultaneous readings of the immediate environment.  The device would give readouts in real time onto my smart phone or an IPAD, recording the data for later reference

Question by ghostman1029   |  last reply

Do avalanching diodes "latch up"?

While working and revising my flyback driver design, I had one of the 1N4148 diodes that I was using as protection get cooked!  (it seemed to fail short circuit) I have not tested to see if the MOSFET survived yet. Obviously the diode needs to react fast and handle avalanching energy well. Any suggestions? are some beefy schottky diodes suitable? Also, does making any ordinary diode go into that avalanche or zener reverse breakdown region cause it to potentially lock up and conduct for a period longer than the EMF spikes I'm dealing with? Or with any sort of hysteresis (like when using neon lamps)? Originally my wimpy glass 1N4148 diodes was wired in parallel directly across the MOSFET drain and source reverse biased. However, carefully examining this tesla coil schematic,it appears that there is both a forward biased diode in series with the MOSFETs, and another reverse biased diode(s) in parallel across the MOSFET & diode. It does not look like a bad idea given one the reverse biased diodes can shunt EMF spikes that are too large while the other isolates them from the MOSFET. My only concern is how lossy that would be at 12V operation.

Question by -max-   |  last reply

How to Build "The Extra Investigator" aka "The Ed Box" Device. Will be featured on new Amazon Prime show. Will Pay for Build!!

Hey Im looking for someone that can help me build an older paranormal device called "The Extra Investigator" aka "The Ed Box". I can't find the right build for it ANYWHERE and only have one pic and the device details, this device is not used by "television paranormal investigators" any longer so its impossible to find any for sale or even other pics of this devices other than the one posted below... it has EMF detection, IR detection and detects "physical events', which i don't understand (BS basically) but it basically is an EMF detector that connects to the compass and points to the em field. Also, Im not sure how the IR detection is utilized. I have not seen this device in action, so this is what i'm assuming because of other gadgets with similar applications. I have found ways to build an EMF detector and an IR detector, I also have tons of parts, bread-boards.. everything needed for the build (have the enclosure and compass on the way via mail) but I need guidance in the build or it built for me. I understand that most serious builders don't believe in the applications of these devices but this is for a serious project and want to show this device on an episode of our new show, also they (the builder/helper) would get a shout out on an up-coming Amazon Prime show, along with payment for the labor and any parts i cant supply (paranormal engineering position for our team may open up if things work out. We are searching for a smaller company/engineer). But! ANY help would be appreciated! No need to make jokes and point out what i've obviously stated, if you cant or don't want to help, pls keep your negative comments to yourself. This device is also going to be a teaching tool for kids ages 12-16 who are interested in the paranormal and want to learn the basics. I wanted to show them some devices they wont see on TV. I'm under no illusions that these devices are 100 percent accurate and will not waste time with non-believers. This is a business situation, the build shouldn't matter. Thanks science peers

Question by langdoncobbb   |  last reply

how can i use dc or ac motor as a generator?

Hi guys i'm doing an experiment by using a dc or ac powered motor as a home generator it is like a backup generator. I'm trying to do the experiment as part of free energy solution experiment. which motor is more reliable as i know that dc motor is good at speed control and it is cheap but it is high maintenance as for ac motor is almost the same as dc motor but the disadvantage of it is the back emf it will produce. hope guys can help me with this. thank you in advance.

Question by azri.azil   |  last reply


RELATED TO DC MOTOR CONTROLLER (EV VEHICLES) 1: Need for large number of capacitors in the power circuit (store the charge and dissipate to which part of the component mosfet or diodes ??) ? 2: what are diodes parallel to the mosfets for ? ( other than preventing the back emf coming from the motor ) and is it have anything to do with firing angle ? 3:advantage of using many mosfets in parallel than using a single mosfet and on what basis must that mosfet chosen? I am from India a college student pursuing my electronics engineering and making motor controller,i am able to get all the circuit details and how the motor controller works but i have above few doubts

Topic by doraditya   |  last reply

Can I use an old floppy disc motor to make a small wind turbine for my solor lights? or an old hard drive motor ?

I want to put some propellers on a PC fan motor or an old floppy drive motor and make free electricity, enough to charge my garden solar lights. I have tried connecting leds to an old printer motor and spinning it, the back emf lights the led for a second. spinning the other way lights the other led in reverse polarity to the first.... My problem is that the motor would continue to spin in the same direction in the wind...only generating electricity for a split second........ Pleeeaaaase help me!

Question by niceribs 

Coil Gun

HiI am planning to build a small (length about 15 cm) portable coil gun. There are some really good intructables out there. (I still don't have enough knowledge of how to build this thing) I found this site to be pretty interesting. http://www.jeffhove.com/robots/coilgunhowto.html How can I make a powerful coil gun like that with capacitors (not that whole blob of camera stuff)? I am hoping that it could be rechargeable, perhaps by a USB connector (5V). But that would not last long right? So I guess by adding some batteries would help. Trying to get this coil gun to the smallest size with a powerful blow. By the way, there is something called EMF that affects the system?Thanks

Topic by J50Nunlimited   |  last reply

How many more times do you have to wrap a ferrite rod to achieve the same power as a toroid bead?

So recently I found a neat low-voltage fluorescent driver instructable, it calls for a large toroid as its inductor, I dont have any large toroids, but I do have a ferrite rod.  What I want to know is if I have to wind 90 turns of wire on a toroid, how many do I have to wind on the rod?  I know it has to be more because the rod looses EMF through its ends.                                                                                                                                   thanks in advance,                                                                                                                                                             Junits15

Question by junits15   |  last reply

Will the fuze in my ATX power supply protect the power supply rails from being damaged?

Hi, I have moded a few ATX power supplys before and my latest find has a higher wattage than my other ones. Anyway I want to make sure that I dont blow up this one. So does the fuze in the power supply on the input protect the whole power supply from over current & shorts or do I need to fuze each rail indervisually? Also I want to protect the supply from EMF from inductive loads. I was just going to connect diodes in reverse accross the outputs. Any ideas on what diodes I should use? Thanks, David.

Question by David97 

I want to convert 220V AC (From my home socket) to DC Current.

Actually, I want to make a Coil Gun for which I require high Current and EMF. So, I went online looking for step-up generators but they are too expensive! So, I thought that why not convert my home output (220V AC) to DC and use it. Please tell me how to make a circuit that converts 220VAC to 220VDC and what components are required. I currently have the following components: 1. Capacitor: 350SV 160uF 2. 1N4007 Rectifier Diodes x10 3. AC Capacitor 250V 1.1uF And I have many more components such as transistors, capacitors, etc. I'll try to get the components that you tell me to, But please help me!!

Question by IshaanP5   |  last reply

How would I go about interfacing an arduino with an old joystick from a wheelchair?

I have obtained a joystick module from an electric wheelchair.  The board says DYNAMIC CONTROLS (C) Mar 2011 GPC80830 REV E.  On the underside of the board, there seems to be test pads labeled the following: +5, MOSI, SCK, MISO, RST.  Slightly to the right of +5 is a test pad that says 0V.  Below are pads labeled SBL and SBH.  Slightly more to the right of 0V is a pad labeled SB+D.  Finally, furthest to the right are test pads BCN, BC, and BCP.  On the top side of the board there is an ATMEGA8A AU 1114 Micro-controller and an empty 5 pin through hole connector. Also soldered onto the board is a joystick that consists of a coil and 4 smaller coils soldered to the board in a + configuration around it (Some sort of EMF sensors?), a weird 4 pin connector and a 3 pin programming port resembling an XLR connector. Any ideas?

Question by gpotvin   |  last reply

Transistor get's really hot and doesn't seem to work. Answered

I'm trying to turn on and off a 12V dc motor/pump (it's one of the motors that squirts the water on your windshield to clean it). Just hooked directly up to the power supply it draws about 1.5A. When I turn on the switch, my transistor gets super hot, to the point I can smell it burning, and the motor does NOT turn on. It's an IRF510 transistor. I copied this circuit from a YouTube video (https://www.youtube.com/watch?v=-g0Q0e1mhIY&feature;=iv&src;_vid=nYjhYKeOOgI&annotation;_id=annotation_856844) and this guy seems to have gotten his version to work fine. I cannot figure out what's going on here. The wires in my picture that go off the table are connected to a 13V power supply on the ground. The diode attached to the motor is a 6A rectifier to handle the emf surge from turning the motor off. Let me know if you have any questions for me! IRF510 Datasheet: http://www.kitsandparts.com/IRF510.pdf

Question by Zamperweenie   |  last reply

Retrofit bug zapper with LED's, Would the high voltage be a problem? Answered

I have a large and good working bug zapper that just had the UV florescent tubes burn out. After pricing out new tubes. which are expensive, it occurred to me to try using UV LED's in place of the tubes. Physically there would be no problem. I can use a 3 inch PVC pipe and wrap the LED string around it. Secure it to the frame and replace the ballast with power supply.  Anyway, I am wondering about the high voltage which will only be a short distance away, perhaps an inch. Would the voltage effect the LED's?  Perhaps an EMF pulse? or are they pretty well isolated and protected? I am using the ones that are coated with water proofing.  Has anyone ever tried using them in a high voltage situation? I have planned on trying this and have already ordered the LED string. I am just trying to foresee potential problems.  I also wonder why I haven't seen any with LED's on the market. Am I actually ahead of the curve on this one?

Question by Vyger   |  last reply

best mosfet config for a powerful flyback driver? would a capacitor across the flyback windings improve preformance?

Well i have an instructable on my singing arc project, i tried the simple 555 driving a power mosfet, but they kept burning out. even the IRF840!!! rated for 500V!!! what am i doing wrong? i tryed using a neon lamp with a series resistor of 4.6K ohms (i think) but it didnt help at all, in fact, it wouldn't even light, yet i got a nasty shock and 2mm spark from the 555 timer, i was amazed that it survived, but not for long, anyways. so i moved on to try a fast diode across the primary, but backwards, to absorb the back-EMF. but it just cut away at the output significantly (from an 2 cm to less than 5mm). it got quite warm in the process too, for the few seconds it was on. i havent tried it yet, but would a diode in series with the power supply, mosfet, flyback, and ground work better? and give a place for the electricity to go? what would a capacitor across the primary do? i heard people doing this and increasing the output, but will it impair an audio signal?

Question by -max-   |  last reply

How to choose wire gauge for Brushless DC motor?

I'm planning to build a Brushless DC motor, with inrunner perm mag rotor and stator on the outside. How can i determine the proper copper wire gauge for the stator windings? How much current will the motor pull? At first i thought it was just "Power = Voltage * current", so knowing the power and the voltage i should be able to figure the current. However, when the motor is spinning it generates back EMF, which counters the applied voltage and diminishes the current. At no load, the motor should draw no current for an ideal motor, and only a small current in real life to overcome friction and losses. In any case it would be much lower than the nominal current. So, for instance, a 1000w motor at 50v should draw 20A nominal, but in most situations it would be less than that? How much is the starting current, when you have to overcome inertia/tire friction? I know the motor can take higher currents for small amounts of time, before it gets too hot,but how can i determine what will be the "average" current. Is there a rule of thumb that motor designers use?  Also, the amp rating for each AWG seems to vary a lot. Some places list a conservative rating that is used for home wiring. But other places list much higher currents. If the stator is on the outer side and exposed to air, how much current can the copper handle for each AWG? Any insight will be appreciated, thanks.

Question by SlickT   |  last reply

Tesla coil antenna?

With the cold and bad weather out there I started again to tinker with my old UHF radio.Trying to build a nice antenna to put on the roof of the hous and such things...While looking up on the various antenna designs I could not help it and followed a few links with antenna designs and specs for all sorts of frequencies.There are things like horizontal or vertical transmission waves or even circular ones.But also some of the basics can be quite different, like whip antennas, dipoles or coiled ones.The later we often see in these keyfob transmitters and receivers for door bells and similar low range, low cost options.Some really old ham radio links got me to the topic or electrically shortening and lenghtening antennas.Things like coils in a whip or added capacitors to match the antenna to frequency and transmitter.A tesla coil usually produces a lot of RF interference, not just on the main frequency it operates on.And from research and physics we learned that for really great distances you need really low frequencies.Like for example the very low bands used for submarine communication around the globe.Here antennas on land can be several km long...The inventor had a few ideas in terms of wireless electricity and communication but I wonder if there is more to it...Despite the broadband EMF a tesla coil produces it is also a really narrow beam antenna.Basically the radiation cone is orientated straight up instead of the usual horizontal patterns we use for communication.The topload again provides a spherical radiation pattern.I am wondering about how a tesla coil would operate as a directional antenna if the topload is replaced with a whip style antenna of a lenght that matches the wavelength...The hip would again provide a more or less spherical beam but the coil underneath would "puch" a directional from underneath.In the classic design the topload is meant to prevent arcing while providing a capacitor so the whole thing is resonant.At lower power arcing is no problem anyways, but what effect in terms of capacitance would a whip style antenna have?Classic pherical or donut style toploads provide little to no gain in terms of antenna properties.If you would use a sphere as an antenna for your CB radio then it would be perfect for very short distance but utterly useless for open range communication.We all know the fun of placing a flourescent light near a tesla coil to show "wireless electricity".Sadly this is more an effect caused by the high frequencies be able to produce the glow in the gas filling.Trying to make an incandescent lighbulb glow is far trickier.Several experiments show that two properly tuned tesla coils can work as transmitter and receiver.But to my knowledge no one ever tried this type of experiment with an antenna on the tesla coil...

Topic by Downunder35m 

Need help with capacitive button cover for Xbox One.

So I hate capacative buttons.  I work for Microsoft as a game dev and we all have Xbox Ones.  They have the worlds most sensitive capacative power button.  We regularly accidentally turn our boxes off with a slight brush of the hand, bumping a coffee cup that was too close or brushing a controller cord against it. I have been trying to build a button cover.  One that will still turn it on and off with an actual press rather than a light glance of the hand.  I have had no luck so far and have been learning about conductive surfaces along the way. The original plan was to use conductive rubber and some scotch double sided tape.  The tape I am using is a clear rubber and has a mm or so of thickness to it.  I bought some gasket punches and punched out a button about the size of the capacitive area of the Xbox One power button, around an inch, and then another in the tape.  I punched out a smaller center hole in the tape to turn it into a washer, and stuck it onto the button and stuck it on the Xbox.  In theory you have to press the button in to make contact with the capacative button to turn on or off the Xbox.  But alas, it still turned on with the slightest of brush still.  I stacked the tape up to four times.  I tried foam mounting tape.  Alternated tapes, stuck electrical tape inbetween, and still the same thing.   On their own the tapes wouldn't turn on the button when tapping them to, but perhaps there was enough distance when touching holding it length-wise rather than flat against. I figure the electricity must be flowing over the non conductive surface and still going to the button.  In the office with all the EMF I seem to be averaging around 3v to the touch.  I have a grounding mat at my desk that when I make contact with takes me under a volt, to around 0.3v but that doesn't make a difference. So I figured I needed a bigger insulator.   I got some larger machine washers where the hole seemed larger than the capacative area, punched another larger button out of the conductive rubber and glued it over the hole.  Using double sided scotch tape I stuck it to the Xbox.  The same thing as before happened.   Even touching the rubber only was enough to turn it on with a light bump.   I figured I needed a ground.  I tried removing the grounding cord from my mat and holding it against the rubber of the button.   It seems slightly less responsive but still turned on easily.   I tried running copper tape along the side of the Xbox to the button to see if that would draw away the charge, but it did not. Taking my rubber washers I used my multimeter to see if they were conductive at all.  They did not seem to be.  Setting it to measure the volts in ac they are picking up about 0.03v, but so is just the air.  But the rubber rings will turn on the Xbox when I hold them though the thick double sided tape will not. Does anybody have any ideas on how to get this to work or what I am doing wrong?  I will admit I don't know a ton about this stuff.  But I don't understand how these materials can turn the button on.

Topic by technicallyartistic   |  last reply

Solar - PV versus Solar Oven with Peltier

I was browsing the site as I am often wont to do, and spent quite some time revisiting old 'ibles covering various solar projects, almost all of which are heat related. I understand from general consensus that PV (photo voltaic) solar systems are very inefficient and one of the worst ways to harvest solar energy (when considering the cost of construction and the energy transfer capacity, etc.) Almost everyone who knows what they are doing suggest that the best (and easiest) way to harvest solar energy is to collect the heat - be it to heat air or water, cook food, or other such purposes.Now, I have recently been fascinated by a discovery relatively new to me, peltier units. These devices, for those who don't know, can work in one of three ways. They can harvest and/or produce either heat, cold, or electricity.Basically, if an electric current is run through a unit, it produces heat on one side and an equal amount of 'cold' on the other. Yes I know you can't produce cold - but for the layman, that is what we call it.Or, if one side is heated while the other side is cooled, the unit produces an amount of electricity from the difference in temperatures. One example I have seen and plan to make use of is in vehicles - if you place one or more of these on your exhaust manifold, or any other location where the engine produces waste heat, and airflow can reach it to cool the other side, you generate electricity from the waste heat energy that would otherwise just be . . . well, wasted.But it occurred to me today, if you had a unit attached in the middle of a solar collector, focusing sunlight on one side of the peltier unit, and isolate the other side of the unit in some cooling medium (perhaps even just air with a heat sink of some sort - more likely a cooling liquid though), how effective would this be at harvesting solar energy (heat) into electricity?Actually, I have been using the more common name of peltier, but I believe that for this application a seebeck unit (which is nearly the same, but different) would be required. As I understand it, Peltier units are used more as coolers and are almost always constructed with Bismuth Telluride (Bi2Te3) and used around room temperature and below; while Seebeck units are good for power generators are often constructed of PbTe or, SiGe as well as Bi2Te3 and are used at much higher temperatures.From http://en.wikipedia.org/wiki/Thermoelectric_effect :The effect is that a voltage, the thermoelectric EMF, is created in the presence of a temperature difference between two different metals or semiconductors. This causes a continuous current to flow in the conductors if they form a complete loop. The voltage created is of the order of several microvolts per degree difference.((more info can be found at the referenced wiki page on formulae etc.))Just curious on if this would ever be a decent way to harvest solar energy into electricity. I have also thought up using a thermal siphon solar heating system in which the liquid flows past one or more water wheels which power a small (and obviously slow) generator - but at that point I believe it would be so inefficient and limited in use as to just have absolutely no practical application. The peltier unit (used as a seebeck unit) would probably do better, but I am not certain, which is why I post the question.

Topic by karossii   |  last reply

Very old shielding materials and techniques for permanent magnets and resulting possibilities

Forromagnetic meterials are not just called that for no reason.It comes from ferrous - iron.Iron has the highest permeability at normal temperatures.That means a magnet is attracted to it very strongly.We utilise this for transformer cores, the stuff inside a relay and the moving latch of the relay itself.Like current from an electrical system magnetic fields like to take the easiest route possible.Air is a very bad medium, so any iron close by will be prefered even if it is at a slight distance.You can check with a magnet, a steel bar and some iron shavings - please cover the are with plate first ;)Slightly less known is the option to also guide and extend the magnetic field this way.If you check how far the magnetic field of a magnet reaches and note that distance,then you can add some steel bars or rods at the poles - the field will extend through the metal.The most powerful example of this are the shielded magnets used for hooks or speakers.Except for a tiny area the entire magnetic flux goes through the metal.So in this lefover area the magnetic flux density will my many times greater than what the magnet alone would be able to.What most people don't know is that magnets also interact with other magnets in terms of their fields changing and distorting.The Halbach Array is a good example of this.Seen as a single magnet the array would have one weak and one strong side instead of even strenght for both.Wherever magnetic fields change a conductor can produce electricity or current.This in return causes an electromagnetic field that opposes the one from the magnets.Just drop a magnet through a copper or aluminium pipe ;)Since these distortions are widely unknow to the hobby tinkerer mistakes can happen ;)In the early days of exploring science some people already knew about shielding.And they also knew that certain metals have certain properties.Where it is quite hard to create a good coil from steel wire, copper works fine as it is not magnetic.What would then a copper shielding do?If you have two moving magnets with only a tiny gap then the resulting field distortions are quite huge.A copper shield around the magnet like a pipe would then react to these changes and also create a megnetic field that works in relation to the enclosed magnet.In simple terms it means the shield would let the magnet appear weaker or stronger depending on the field change.A quite old document I found gave some hints on how people thought in different directions back then.It was in regards to the design of a magnet motor by the way.Here various magnets were shielded in tube made of a copper-bismuth-alumium alloy.These tubes were then electrically connected so it created a single loop conductor.The claim was that the resulting electromagnetic field of this ring would drive the fields of the enclosed magnets sideways out of alignment.Like bending straight pastic tubes sideways.This "pulsating" would always happen when the magnetic binding forces reach max and so basically drastically weaken this binding effect.Another document talks about a "magnetised brass rod".A holes of the rod diameter is drilled through a block magnet.Not from north to south but through the middle where the flux is greatest.The claim here was that if that rod rotates fast enough a very low voltage with a very high current will be generated.Sounds easy and interesting enough that I might have to test one myself one day.The best one however is what I consider a hoax or being as good as Starlite.Someone back in 1908 claimed to have created a material the reflects magnetic fields.In lame man's terms it would be like an insulator around some electrical wire.The claim and some pics showed it, was that no magnetic field can pass the material.Or to be correct only a tiny fraction of what would be possible through air.A small magnet inside a longer tube of this material would create almost the same attraction to steel at the tubes ends as on the magnet itself.Measurements showed the field strength would be almost equal to a long mangnet of the same field strength.Imagine guiding the field of a big and powerful magnet through a tube around some corners or other magnets and then end in just a tiny hole for the entire flux...Too bad he never shared his secret formula to anyone knows to mankind.Isolation...Imagine you have an array of changing magnetic fields and quite strong magnets.Then you might face the problem that your focus on the "working" end neglected the other end of the magnet (stack).Providing some iron core material will keep thes field lines contained and away from interfering with your setup ;)But it also allows to use te otherwise unused end of your magnets more directly.For example by guiding to another magnet to affect its field strenght ;)Placing a sheet or steel between two magnets in a setup provides a "shared pole" so to say.If you have a north and south pole on a rotor at a distance of 5mm then a sheet of steel between will drastically weaken the strenght and reach of this combined field.It is like pulling the arch between the magnets down to make it more flat.And at and an angle the resulting field will also be slightly angled ;)Capping...When I first encounter this many years ago I couldn't really make sense of it.Quite complex..If you check the magnetic field lines with iron filings or similar then you notice how they go in a rounded manner from pole to pole.This is because the single field lines are of equal polarity and will dirve apart like opposing magnets.By capping the ends of a magnet you provide a short.Instead of diverting out like mad they will follow the cap and create very intersting magnetic field in return.If both poles are capped it is like pressing the magnet flat but without having a field on top of the oles - only aorund the center part.For this the thickness much must match what is required for the flux density.As a rule of thumb: if the end is still very magnetic then it is not enough material tickness ;)Interacting fields in a tube...This one is quite old too and seemed to have found no usable inventions apart from simple magnetic spring replacement systems.But it gave me some clues about Tesla "earthquake machine" ;)If you place a magnet in a tube and at it's ends magnets with opposing fields to the one inside then you can fix this magnet in place.Push one magnet deeper and the distance from the inner magnet to the other end will shrink the same amount.In this old paper two coils were around the pipe with the inner magnet between them.In this gap and at about the same width as the magnets length another coil was placed.Violent shaking would then create electrical energy at much higher level then modern shaker torches.In return an AC current on the outer coils would cause the inner magnet to move back and forth to create electricity in the center coil.According to the paper possible uses include: core less transformer, measuring minute changes in AC voltages, providing free power from a running motor...The last one had me stumbled for a very long time.Until I considered a different configuration.The whole thing is basically a linear DC motor - with correct timing of course.And in some motors we use permanent magnets.I am starting to wonder what would happen if we would design a rotor magnet like this?The running motor would be subject to constant field changes that affect the rotor.And a normal motor is always "even".By using four magnets instead of one we can push the field really flat.This means the area where the coil would operate (about 1/5 of the magnets area) will have a much stronger field.The resulting torque should be higher by about 25% !!Even a simple two coil model setup should show a significant increase in performance here.Timing is critical here but I tried some calculations based on 8 poles and the required "on times" for the coils.In a standard motor configuration with a single rotor magnet the coil is active for about 12° of the rotation.With a 4 magnet configuration this "on time" can be reduced to under 8° of the rotation to get the same amount of torque.An energy reduction of about 4% if you neglect losses and only think in time.If you think in terms like impulse energy then we are talking of about 15% !Shorter on time but still much higher flux density overall than for the long standard timings.Going the long run now:If you check how most DC motors work then you realise soon that for most one rule seems to followed.Only use one coild pair at a time.This is quite contradictive if you consider the geometry and options.A dual commutator would allow to use a second coil pair with a field OPPOSING the magnets instead of being attracted to it.After all: on you bike you pedal with both legs and not just one...And if you do it professionally then yu do the same as I suggested for the motor - you use the up pull of your legs as well.Doing it brushless only requires amodified h-bridge desing to drive the second coil pair at the right timing.Some will now say that it requires twice the energy, I say that for the same motor size your get twice the torque!Just imagine what that means in possible weight reduction for a motor - or its size to deliver the same torque at the same power levels when a normal motor is used ;)The more poles the more complicate the precise timing but no big deal really with modern electronics.Can it be improved even further?I though long and hard about that one until I considered EMF.A DC motor produces a lot of it when the elecromagnetic field collapses in the the coils.We do not utilise this energy...There is a tiny delay until the released energy levels are at max.My theory is that it should be possible to divert this energy into another coil set.If that coil is not the next active but still within a strong enough field area then the EMF would actually add to the drive of the motor.Only downside is that according to my calculations at least 16 poles would be required to get an optimum result.Way above of what I can create in my little garage :(In theory it should then be possible to reach about 98% efficiency for the motor....

Topic by Downunder35m   |  last reply

Printer disconnecting or USB port disappearing in Windows

First I thought to make an Instructable out of it but realised there are too many different printer models out there, so this time no images. What is this about you might wonder? Well, let me tell you my story first and you might see similarities to your problem. It all started with me getting a new PC as the old one got memory problems (RAM modules failed). After a few successful prints I noticed errors coming up in the log window. Mainly things like communication problems and that some data is sent again. Realised that on my new PC I did not check the speed settings for the COM ports, so I adjusted them to match the printer board and moved on without even bothering to check the logs. Then, half way through a bigger print, it all stopped and I could not even connect to the printer anymore. After a power cycle on the printer all was fine again but the error kept coming back every now and then. At this point I started to read up on the problem and the most common recommendation is to print over SD - too bad if your printer does not support it and too bad it does not address the issue at all! A few more technical answers pointed to the Logitech drivers, especially mouse, keyboard and 3D vision. As I was using the same outer hardware as before and also the same drivers (and same version numbers) I simply ruled this one out too, although it might be a vital clue for others. When starting to get frustrated and after opening a cold blonde I remembered that I had a similar issue a long time ago and that it was related to loose wires on the screw terminals for the power connection. Measured it all but according to my trusty multimeter all was fine. Now comes the fun part: I friend of mine with a HiFi fetisch was here when I testing the connection and he started laughing at my attempts. He explained that ALL his connections, no matter if power or audio signal are oversized! Here I started to wonder if he is up to something and looked up similar circuit board mounted power plugs. To my surprise they are all rated for anything between 1 and 5Amps. Even without a heated bed powered by the printer board I think everyone will agree that a max 5A connections is not enough. My frined then offered to check the plug and connector at his place - what a great thing to have friends :) He used a signal generator and small speaker with the plug as a connector between them. With an oscilloscope connected to both input and speaker you could see, while moving the plug, that the audio signal become somehow unclean - there where spikes and missing bits everywhere depending which way you wobble the plug. After taking the whole thing apart the destructive way we saw the cause: overheated contact areas with discolored surfaces. I replaced the plug now with a 250V/20A one from an old laser printer and had no USB or connection issues ever since. Ok, what's the thing with power and USB problems on a 3D printer? Almost all printer boards have the ground connections bridged to avoid interference on the USB signals. This mean, in case of a faulty power connection or one that is "dirty", the USB port on the computer can receive back EMF signal or even a voltage spike. In return a smart bios either disconnects the port or disables it until the problem is solved, in our case by restarting / reconnecting the printer. But even with no obvious signs of power problems you can get  a so called "dirty" connection. Dirty covers all from corrosion, worn springs for battery compartments, overheating or in the old days burnt relay contacts. For our printer it usually means that either the soldering connection on the board or a screw came loose, in rare cases like mine an undersized connector can burn out due to being unable to handle the currents. The bad thing is that you can not always spot these problems the easy way... Is there an easy way to tell that my USB problem is caused by a faulty power connection? Yes and no. Some boards offer indicating LED's, you connect power and the LED stays on even if the printer is disconnected from the PC. If it is more than just a Power on" indicator" this LED will be off after the printer stops working and in the device manager your serial port for the printer is gone. You might also hear the warning sound from Windows in regards to a device being disconnected. If all the above is true than most likely your power connection has a problem somewhere - if in doubt replace all screw and plug connectors for the power. Sometimes the problem is less obvious. Your print software might show communication problems in the log window or re-send a lot of commands. If the speed selection for the com port is the same as for the firmware of the printer board and as set in the printer software, it could also be a power connection problem. But to be on the save side try a shielded cable with ferrite cores on both ends first for the connection between computer and printer. Can I take any measures to prevent the problem? Sure, you could solder everything and make sure the wires are fixed in place so they won't move. But a simple indicator might be enough: Solder a piece of LED strip to the power connection on the circuit board - if the connection has trouble the LED's will show it in most cases by changing light levels or flickering. On top they act as a nice light to see what's happening during a print.

Topic by Downunder35m