Circuits Answered

Can some one give me a clear definition of a transistor.

Question by Dr. Kreap   |  last reply


circuit board

 Hi guys, I am looking for a high quality circuit board manufacturing  that can deliver high quality  circuit board ASAP and with fairly reasonable cost .  any suggestion?

Topic by Michael2000   |  last reply


Circuit Problem? Answered

Hey guys i just made this circuit ( pic provided ), The problem is when i  clap the led that indicates the circuit is off turns off (power goes to the relay coil) but  the circuit off indicator led turns back on after a few sec and the relay does turn on at all. (Yes the relay works) And another thing I observed is that when i take the coil wires off and attach them to an led instead of relay it works correctly and the led stays on till i clap again to turn the circuit off.

Question by SA-DIY   |  last reply


inverter circuit

I have several BD139 transistors, several types of transformers, blocker diodes and 40pf 50v capacitors. can anyone show me a simple schematic to convert low voltage to high voltage?

Topic by buddybro   |  last reply


Circuit not working...

So I made this circuit (http://niotronic.blogspot.mx/2013/07/clap-switch-with-ic741-and-cd4017.html) but it doesn't seem to be working. When I connect it to power the relay is in on position and the led is off. No matter how many times i clap it doesn't seem to change state. Can anyone please tell me what i could've done wrong? Note: when i touch the bottom of the circuit ( on some pins between 1 and 4 of ic 741) it seems to change state. Help would be greatly appreciated thanks. (This video: https://www.youtube.com/watch?v=zFu0pBvpmIk shows this circuit in action. It seems that he used an LED instead of a relay. I also found similar circuits here: http://www.electroschematics.com/5643/sensitive-clap-switch/    http://www.homemade-circuits.com/2011/12/make-simple-electronic-clap-switch.html     http://circuitdiagramcentre.blogspot.com/2011/12/make-simple-electronic-clap-switch.html)

Question by SA-DIY   |  last reply


Circuits and Circuitboards

I would like to make circuits using paper and a conductive ink pen, but there's not way to "attach" the components to the paper. I'm looking for a conductive glue, like epoxy or super-glue, I can apply directly to the point of contact between the paper and the component. Can anyone suggest a product, or how to make such an item? Thanks, Kevin

Topic by kevin.t.stein.3 


Circuit not working? Answered

Hey Guys, a few weeks back I posted a question about a clap switch with an IC 4017 not working (relay not turning on). Well I tried to make the project again. The problem is now the relay wont turn off (-_-). (https://www.youtube.com/watch?v=zFu0pBvpmIk) video of the project by another guy ( He doesn't use relay, instead he uses an LED. The problem with mine is that when I give it power the CIRCUIT OFF LED is off and the relay is on, indication that the circuit is in on position, so far so good. But when i clap the CIRCUIT OFF LED turns on indicating that the circuit is off but the relay stays on. The first time I tried, i didnt put the diode near the relay, same result. THen I put a diode (the wrong way), nearly burnt my hand. This time i put the diode in the same way that im supposed to but the circuit still has the same result. I have uploaded the schematics, Hope someone can help me. UPDATE: I was using MJE13003B instead of BC547. When I was using the mje13003b it was very easy to turn the circuit on and it used to come on at first try. When i inserted the BC547 the circuit was in off position I clapped and it worked like a charm the indicator led turned off and the relay turned on. But when I tried to turn it back off, everytime i clapped the status led blinked and thats it, It just blinked, the circuit would be still in on position. I wonder whats the prob since turning it on is easy and turning it off is impossible. NOTE: Now its the same with the on position. Whether its in on or off position same thing happens. In one of the million clap it turns on. Thanks in advance. -Prickly Potato

Question by SA-DIY   |  last reply


Charger circuit

Hey there, I'm planning to build a portable stereo speaker box thingy (you know what I mean). In order to power the 2x10W amplifier I want to use a 7.2V 1400mAh battery pack from an old RC car. As the housing of the box will be sealed I want to implement a mechanism to charge the pack. For this I wanted to achieve 3 things: -If the Power-Switch is turned on, the amp should be powered from the power line -If the Charge-Switch is turned on, the battery pack should be charged -If both of the switches are turned on, the amp should receive power from the power line while the battery pack is being charged. I have thought of the following cabling (see attached picture for a schematic) The blue box is the amplifier, the green box the battery pack and the orange connectors are tamiya connectors (the ones for RC cars) The first switch (marked in green) is a normal DPST switch which establishes the connection with the power line as well as the connection with the battery The second switch is a SPDT switch and activates either the connection between the battery and the amp or the connection between the power line and the battery. Will this work the way I think it will or does this configuration any faults? If the latter, what can I do I have to change? I'm actually really new to electronics, this if my first project so forgive me, if this setup is actually BS Cheers and sorry for the long post ^^'

Topic by Felixkeeg   |  last reply


Soundcard Circuit

I've been looking for a soundcard that will work for what I need for a project I'm working on. I need about 6 inputs I prefer to make it myself, just to make it more fun and challenging :) I don't have much experience with this kind of thing so I need some help. I can't seem to find the information I need by myself so here I am asking for assistance. http://www.netams.com/~anton/usb-adc/index.html The texas instrument pcm2900 chip that is used... Do I need 6 of them for 6 inputs? I need them to be completly separate.  He says he is running 2 inputs off of this chip. I guess the 2 inputs share the converter? When I get to programming I need to have 6 separate data streams (one for each input) Thanks in advance for all advice!

Topic by amplifihip 


Switching Circuit

Hi, I want to build a Auto-Switching circuit. I would appreciate if you could help me on circuit. Sorry for my ignorance in circuit design. There are two power sources A and B. The A is 12v and B is 3v.I would be utilizing the power from A only when B is turned On. So an auto switching circuit is required in this scenario. The circuit should sense if B is On, if so it should let A On.

Topic by arunsun   |  last reply


Pulse circuit?

I need to make the circuit that every time it charges the capacitor to a certain voltage (e.g. 5v or 12v) it discharges it

Question by Dantex   |  last reply


Circuit boards

Does anyone know where I can find replacement circuit boards for my Gateway model number vg70 laptop

Question by CarletonG   |  last reply


Circuit Timer

I would like to be able to set a time, small like .5 seconds, and be able to power a 12v circuit for that amount of time, any ideas? 

Topic by ReconIII   |  last reply


Circuit tracer???

Can anyone tell me how to make a device that can scan and trace an entire electronic pcb and give a schematic result ???

Question by 10sicnarf   |  last reply


Protector Circuit?

How can I make a circuit that will protect an LED when I plug it into a traditional light bulb plug?  hint- homemade LED light bulbs.  

Topic by Buzzsushi   |  last reply


Circuit design

Hi, I’m hoping someone could help me. I’m looking to design a circuit for a college project that controls a 240v light. The circuit and light will be controlled by a switch however when the switch is first turned on the light needs to remain off (no power supplied) regardless of the amount of time the switch is on. If however the switch was turned on off and on again then the light needs to come on. Any ideas of a circuit and components required to produce something like this? Your help is greatly appreciated.

Topic by Worby10   |  last reply


Charging Circuit

I was wondering if anyone had any ideas on how to make a circuit so that I could charge a battery, but that I can also power an amplifier when the battery is not charging. Currently I have a switch that switches between a charging circuit and powering the amplifier, but I was looking for a way to do this without having a switch that I have to control

Topic by Fozzibehr   |  last reply


door circuit?

When door open led on when close led off for 5 doors windows etc.. display led on one mainboard

Question by fawzi 


Circuit not working?

Hey Guys, This is like the 5th question regarding the same circuit. Maybe its because the circuit is a bit hard to make or .. idk. Anyway I tried it on breadboard and in the 5th attempt it worked but now that i soldered it on the normal perfboard its not working. It doesn't detect the clap at all.(the microphone is properly connected).I dont know what I did wrong. I bought a multimetre recently so if you could tell where im supposed to see what voltage that should make it easier to troubleshoot the circuit. BTW Pin 12 and 13 are not connected because i remember when they were connected on beadboard it wasnt working.

Question by SA-DIY   |  last reply


Circuit Help!

Hi, I'm trying to put together a basic circuit for charging a capacitor/s with a built in LED to indicate when it's charged. I've created a draft on Multism but can't seem to get it to work. I'm a complete novice at electronics and have pieced it together from various schematics I've found. Help please! :)

Topic by si_eng   |  last reply


circuit imprime

Bonjour ,j'ai un ecran plat qui marche 5 s et apres plus rien.je l'ai demonte .allimente plus rien ,ni image ni voyant power.

Topic by riadi   |  last reply


Circuit not working? Answered

Hey Guys I just made this circuit (schematics provided) and it doesn't work. The problem is that the  at the output of the 2N3906 transistor the voltage is only 0.5-0.7. So that isn't powering anything. I was wondering if anyone could tell me what the problem is. (the first pic is the original and the second one is the modified one with i built). Thanks in advance. -Prickly Potato

Question by SA-DIY   |  last reply


Blinker Circuit

Hi i am looking for a good model for a turn signal circuit. i am trying to make turn signals for my mower (not a joke) and i need a list of parts i need to buy, and a image of the circuit i already have the lights and switches. i would like to have it so a switch is for each side, and   i would also like it to be able to do hazard lights, i dont know if i would be able to do that by switching both switches on at the same time?. but what ever you got to help me would be awesome. thank you

Topic by RC Instructables   |  last reply


LED CIRCUIT?

Hi would this work if i used 5 12v Leds(parallel) and connected 3 9v pp3 batteries(parallel) for power, also would the LEDS need there own resistors each? look at image for detail

Question by jbutcher05   |  last reply


Will this circuit work? Answered

It works, but are there any problems with it that might fry the chip or something? Also, I didn't know if audio ground should be connected directly to the amp ground, and I saw one schematic that had a 10K resistor in between so I just did that.

Question by 7654321   |  last reply


Circuit Help

Hi, i saw a video by the king of Random     https://www.youtube.com/watch?v=hCxmn1ERbXc He hand cranks up a drill to charge a phone.. but what i wanna do is similar but different, instead of charging a phone i want to charge a battery and what i need to know is, what component do i need to stop the current from the battery to go back into the drill once i stop cranking so it doesn't depletes..  

Topic by Arghus   |  last reply


Electronic Circuit

I have a spst relay(operating voltage-12v) using for switching the solenoid valve(24VDC and 0.5Amp) which connected through 24 V battery. relay is again connected to the transistor BJT NPN . So please suggest me that which transistor is most suitable.

Topic by jay_3189   |  last reply


Circuit help

Been decades since I did any circuit design and I have a fairly simple need someone will certainly have a simple answer for.I need to run a simple pulse output from a 5 minute timer into a circuit that will have 4 outputs. Each pulse in will cause the next output in line to go HI, with the others all LOW. 5 minutes later, the HI will move to the next Output, with all the others again at LOW. Once the 4th and last output has gone HI, it will wrap around to the first output again, and so on. Sound a bit like a Ring Counter, but there is no CLOCK pulse here. Just a short pulse every 5 minutes or so to the input. Any help would be appreciated. This isn't rocket science, so simple and cheap would be a plus.Thanks.

Question by gjforeman   |  last reply


Sound Circuit

What I want to do is set up a switch so that every time it is toggled, one of two sounds are played on a speaker (which I also don't know how to connect). How would I go about doing this? This is for a homemade Aperture Science Handheld Dual Portal Device.

Topic by elementcollector1 


circuit board

I need to make a circuit board for a project. It is all 12vdc, I have a 1a fan and a 6a thermoelectric device one setting 1, plus another 6a on setting 2, and a 3rd on setting 3 So 1 is 7a 2 is 13a 3 is 19a How to make the board. Also a second device has the 1a fan plus a 4watt element, plus another 4w on setting 2, plus another 4w on setting 3 So 1 is 1a and I think 0.4a= 1.4a 2 is 1.8a 3 is 2.2a. I think

Topic by Johnieahenderson   |  last reply


Will this circuit work?

Ok, so I'm building a giant led array and I'm running it off of a PWM chip and a few shift registers. Given the number of addresses and variables I need for each one, I'm guessing that the micro running the show won't like that too much and will be a bit slower than I'd like, and i'm not sure if it will be slow enough to cause irritating visual inconsistencies. This got me thinking, how did tube TVs do it? They had phosphors that slowly released their charge and therefor looked alright. Thats how I arrived at this circuit. Will it pretend to be a phosphor well enough or will it need something different?

Question by The Ideanator   |  last reply


Timer Circuit

I found this simple circiut on jamesyawn.com, and was wondering if and how to change it so that it could time in the minutes, longer than it does already. I don't know anything about electronics, aside from soldering, and basic connections, so try to give a simple-ish answer. I also wondered about what transistor to use (like a radioshack part number). The circuit I was talking about is under "discrete timers".(update, more questions)What kind of timing (like how many seconds) would I get with this?Using the same stuff shown on the schematic?Also, how do I pick a transistor?Are they interchangeable? What specs should I be looking for? If this seems like too much, could someone give me a link to a site that would be willing to help with (very) beginning electronics?AND, how would you recommend making the transfer schematics for home-etched circuit boards? I can't get the component spacing right.

Topic by John Smith   |  last reply


Theremin Circuit?

Does anybody have a theremin circuit that doesn't have coils? I need it to be compact so programming seems ideal. A PIC solution might work...any suggestions? Any other processor is fine also. No, I can't use a light theremin... And no, I can't use Harrison Instruments' because its too big and too many connections. If possible, then this is to be used on fruit flies to see how much activity they do when foreign substances are added. Again, if possible if a PIC solution is used, then can the PIC detect when the flies move because they change an oscillation. Most likely I will wind a coil and place it in the jar and then have it detect. The best way would be to use the PIC to print an output via some sort of display so that the scientific results can be tested.

Question by blinkyblinky   |  last reply


Of solder and circuits

To dodge an onslaught of summer boredom, I'd like to fart around with small scale electronics projects (LEDs, maybe a circuit board, etc.). I hope that by the time I finish farting around, I would have something nifty to post on this website. Unfortunately, I have little practical knowledge of this stuff (other than what I learned five years ago in high school electronics). I mean, I don't even know how one technically refers to "this stuff." Can anyone recommend some good books or a general method of wetting one's feet before jumping into the pond? Highly technical sources are obviously beyond me at this point, so I'm looking for introductory-level information that can be flexibly applied to whatever bizarre project pops into my mind on Friday afternoon.

Topic by ringtail.jack   |  last reply


LED circuit?

I recently purchased a few LEDs for a project, 2 blues and four reds. I need a way to power them all for months at a time. Would a nice soul be kind enough to draw up a schematic for me, considering I know NOTHING about this stuff? Here are the schematics, taken right off the back of the packets. 4 Red LEDs: Forward Current: 28mA max Forward Voltage 2.6 V max 2 Blue LEDs Forward (supply) Voltage: 3.7 typical, 4.5 Max Forward (supply) current: 20mA typical, 30mA max Any help?

Question by Rotten194   |  last reply


Circuit help

So, my brother tasked me with making him a customizable doorbell for his house for Christmas (of course he didn't tell me till last week, but whatever). looked around at a bunch of stuff online and found a few decent items. some of them use those voice recorder modules from radio shack...which  might work, but I've used them before and they're pretty quiet. also, not the best sound in general from the mic used to record to them. so I found this thing http://spritesmods.com/?art=doorbell&page;=1 which is a riff on this thing http://elm-chan.org/works/sd8p/report.html  which uses an ATTINY85 to play audio via the PWM output from an SD card. I like this guy because it's gives more options for sound and is generally more "gee whiz". however, the guy built it from scrap parts and has some admitted flaws in it, notably the power supply and the audio amplifier. so, I'd like some help figuring out how to build the same thing, but with a more "correct" power supply and amplifier. also, not exactly an electronics wizard so the fact that there are a billion different chips listed as ATTINY85, I wouldn't mind if someone can make a more sensible parts list (there aren't that many parts). I plan to trigger the thing with an off the shelf wireless doorbell type thing.

Topic by crapflinger   |  last reply


Small circuits and Small circuit wire? Answered

Hi,  I am new to the fiddling with wires stuff. Just about to dismantle a bluetooth headset and I notice that the wire inside is tiny!! I intend to lengthen the wire to the microphone and earpiece but my wire is nowhere near as thin. Will it make the circuit run slower if I put thick wire on thin wire?  If I need it, where can I get thin wire from in the UK?  Also, is there a better nomenclature for thin wire or thick wire or have I nailed it? Thanks in advance Phil

Question by comedy_phil   |  last reply


(SOLVED) Break circuit = Make circuit?

Basically, what I want to do is activate something when there is no current somewhere else. Examples of uses of this would include turning an LED on when there is no light on an LDR and turning it off when there is light, rather than the other way around, along with turning an LED on when a circuit is broken by opening a door. Apologies if I have not been clear enough. Is this possible?  EDIT: Thanks to NachoMahma, I have it set up with a transistor. I will post a schematic if anyone is interested.

Topic by __DELETED__   |  last reply


Basic Circuit Question? Answered

I am making a box that when opened will sound an alarm.  When it is closed, the contacts are touching, thus completing the circuit.  When the box is open they are not touching.  How can I make a circuit that will realize when theyre not touching(without using an Arduino or other programmer)???

Question by crocboy   |  last reply


Is my circuit OK?

I'm building a circuit that uses two 5V inputs and one 24V input. I drew a schematic that I think will work but I want to make sure it does before building it. Can somebody tell me if I'll really get 5V and 24V?

Question by yonch   |  last reply


Random Output Circuit

Hi all I need to create a circuit that, when triggered, closes one of two relays. Any ideas? Nigel

Question by bob_boyce   |  last reply


electronic circuit simulator?

Where can i find a free circuit simulator doesent just show signals but that shows what the things do like leds light and switches switch and stuff

Question by coleyy   |  last reply


time safe circuit

I'd like to make a time locking box that is equivalent in function to this:    http://www.thekitchensafe.com/ I was wondering if there's anyone out there that would be willing to draw up a circuit for it as electronics is not something that I know how to do.  I could do it with arduino but I don't really want to tie up the board that way.  I assume it uses solenoids to operate.   I'm also open to any other ideas/advice people have.  .  

Topic by csiebe   |  last reply


LED circuit on flashlights

I have over 2 months trying to understand the circuit that LED flashlights have  that last a lot, yhe Joule Thief is not the circuit, because the flashlight circuit is just a capacitor, a resistor and a transistor.

Topic by GeorgeElectronics 


dtmf circuit problem?

This is the circuit for dtmf based robot using cd4514 for 16 outputs it has 2 l293d ic for controlling 4 motors will this work??

Question by agent555   |  last reply


Would This Circuit Work?

A while back I designed this circuit, and to my knowledge it should work, but I just want to get a second opinion. It is a game in which there is a circle comprised of 12 LED's and the goal is for the user, to press a button, and stop clock so that the green LED in the circle is lit. There is another switch in the circuit so that the user can reset the game at any time. I'm sorry that the picture is very faded and a bit cluttered. Any help is appreciated, thanks!

Topic by FrozenStar   |  last reply


What is this circuit symbol? Answered

I'm wondering what Q22 is, I have never seen that before.

Question by T_T_   |  last reply


LM35 circuit design

Hi, any advice on putting an LM35 into a circuit to control a small (120w max) DC immersion heater element so that it maintains water temperature around 38C ? Thanks

Topic by RionZion   |  last reply


simple logic circuit

Uuhhh..I'm not really sure about this..i'm an electronics engineering studentand my instructor in Logic Circuit and Switching Theory requires us to make a project which will include logic gates.now i searched in the net for some ideas i found two..but i know i shouldn't copy their projects..can anyone help me?link2link1thanks guys!

Topic by hazelcharisse   |  last reply


Basic LED Circuit?

I brought 5 RGB LED's just now on the interweb, but I have no clue about circuits all I know is theirs parallel circuits which I will be using and I have a power source of 2 AA batteries. Sorry for such a newbish question, any links to and learning articles would be greatly appreciated.

Topic by Antexter   |  last reply