Limit current to 170v 5 amps?

So... I connected 120v ac mains power to a bridge rectifier > capacitors to smoothe > switch > output... how can I prevent the breaker from...breaking.  Also the integrated bridge rectifier can only take 6 amps for long amounts of time.  I need to somehow limit current without limiting voltage (at least to much)

Question by TypeNameHere 1 year ago  |  last reply 1 year ago

Wearable 5 V 9 A power supply? Answered

So I am making an electronic t-shirt with a very bright screen that gobbles up amps. At it's probable peak usage it will be using 9 amps (or 8.697, but I always feel safer sizable margin of error). Luckily this will only be at its peak for a few seconds (at most 10 seconds, probably less) when it starts up. Next it will use  between 4.5 to 3 amps continuously, and later will  be using closer to 1 amp. All of this is at 5 volts, and I will be stepping down from 7.4 volts. As if this wasn't hard enough this is battery powered, so good efficiency would be nice. I want to minimize the amount of power lost. Is there a power supply that can do all this and still be wearable? In short, I need a wearable 5 volt power supply that can provide a few seconds of 9 amps and 4.5 amps continuously.  Thanks! Edit: Thanks Everybody! For people who find this in the future, here’s from saving you from having to read through all the posts… In the end I found the answer to my problems was cutting the peak amps it needed to consume it half, bringing it down to around 5 amps. What I ended up choosing was the R-745.0P power supply. Look at the last page of the datasheet for clarification on how to wire it, and when it comes. The mpilchfamily thread talks about safety, which is important and worth reading if you want to know about it. I wasn't sure on whether or not I should go with the R-745.0P and all the supporting components or the UBEC 2-5S, which is an all in one package. I chose the R-745.0P but it’s up to you!

Question by GenAap 5 years ago  |  last reply 5 years ago

When to use solar cells w/ 5 to 8 amps vs. cells with 3.5 amps?

What are the ups and downs of using solar cells with higher amps like 5 or 8amps does it all break down to use of space? Do you have any examples for me?

Question by golfdeals 9 years ago

How to configure LM317T to deliver 5 amps?

Hi guys, I'm new to the site. I wonder if someone could help me resolve my problem. Well, I'm trying to build a Laptop AC Adapter, but I can't get these components right now: -A Transformer -A voltage regulator other than LM317T and I have no experience with other ICs. So I'm using a DC to DC converter. The input power supply is a Z12 Lexmark printer AC adapter. It gives a DC output current of 830mA under 30 volts (actually it's 37.5 volts, I've checked this with my multimeter). However, the output I would like to get is 4-5 amps under 19.5 volts. I would like to mention that I've already given it a try. But the output current I've got wasn't enough to feed the laptop. I've used an LM317T and adjusted the voltage with a 6.6k resistor and a 47k potentiometer down to 19.5 volts. If there is a way to boost up the current with a joulethief or using a set of transistors or parallels LM317Ts, please tell me. Also, I hope that you give me the part number of all the components to match up with the LM317T because I must use this type of regulator. Thanks for your help and please consider my situation.

Question by junkrecycler 6 years ago  |  last reply 6 years ago

How to change old speakers into amp.

Help! I've got a pair of JVC 5-way speakers that I'm trying to power with a Danelectro E-studio 9V headphone amp for my guitar. I've been successful using it to power some old walkman type two way speakers by just plugging into the headphone port. The JVC's will take up to 400 watts. I made a small port 1/8 plug but to no avail. Any ideas?

Question by 10 years ago  |  last reply 10 years ago

9 volt battery to power 5 watt tube amp

I searched for so long for the internet to answer me and nothing i want an inverter that will take a 9 volt battery and power a 5 watt tube amp. the amp is handwired, there's no circuit board and i want to believe its possible

Topic by ethan.heil 5 years ago  |  last reply 5 years ago

more powerful, portable amp

I was messing around with some op-amps, building variations of the CMoy amp, etc. But I became depressed quickly -- these ICs' data sheets say that at the safe maximum of 15 volts, they can only pump out around 1/4 watt of power on a single channel! Well, i have a full range driver that really needs more power to sound decent. I was wondering what the normal way of constructing an amp would be if I were looking for 5 to 10 watts of power. *edit*: i'm not looking to run this thing off of batteries... i'm sure at 10 watts, a couple of D cells would get drained rather quickly... I recently cracked open an old 4.1 computer sound system (by microlabs) and scrapped the 5 drivers (4 satellites and a 5 inch sub), two big 3700 uF caps, and two JRC4558D dual op-amp ICs from the amplifier. I read up on the JRC chip (actually, just the data sheet from the RC5448D, the texas instruments flavor, i guess the JRC is discontinued) and it seems that this thing only puts out a max of 200 mW per channel, and typically around 90 mW. Ok i know those speakers didn't get THAT loud without distortion, but i am CERTAIN it was more than 800 mW for those 4 satellites. I am a new computer engineering student, so i can understand the physics behind the electronics, but i am nowhere near the level to start reverse-engineering that amp board. So how did these speakers get driven so hard? THANKS for reading!!!!!

Topic by samurai1200 11 years ago  |  last reply 11 years ago

DIY Ipod Amp Kits

I have all put together all the parts to make your own iPod Amp as seen in ReadyMade magazine issue 23 and Instructables.The kit includes:Velleman Amp kitSpeakerArmy Surplus Case1/8" Stereo JackWireLEDResistorNuts and Bolts to secure speakerPower Switch6AA Battery Holder w/ snap connectorThe price is $45 + $5 for shipping. You can follow the step by step instructions at:,-JoeYou must pay with paypal and I will only ship to the US, sorry I just end up losing money any other way.

Topic by joe 10 years ago  |  last reply 8 years ago

Vacuum tube amp help

I just bought a lot of 125 vacuum tubes on ebay for 30 dollars including shipping (the seller didn't list what tubes were there, just said a crate) I got the following (if the same name is listed 2 times in a row, then I got 2): 10JA8 12AD6 12AE6 12AF6 12AU6 12AX4GTA 12BD6 12BE6 12BG6 12C5 12CN5 12CU6 12J8 12K7GT 12RS 12X4 17AX4GT 17BR3 18FW6 18FX6 18FY6 1B3GT 1G3GT 1G3GT 1S4 1S4 1S5 1T4 1U5 1U5 1X2B 21LR8 2BN4 2BN4A 2CW4 2CY5 32ET5 3S4 3S4 3V4 4BQ7A 4BZ6 4BZ7 4BZ7 50B5 5AT8 5AT8 5AT8 5AT8 5BR8 5T8 5T8 5T8 5T8 5U8 5U8 5U8 5U8 654A 6AB4 6AF4A 6AG5 6AG5 6AL5 6AL5 6AM8 6AQ5 6AQ5A 6AS8 6AT6A 6AU6A 6AU6A 6AU6A 6AV6 6AV6 6AX4GTB 6BA6 6BA6 6BA6 6BA6 6BA6 6BE6 6BE6 6BJ6 6BK7B 6BN4A 6BN4A 6BN6 6BQ7A 6BQ7A 6BQ7A 6BQ7A 6BQ7A 6BU8 6BZ7 6BZ7 6BZ7 6BZT 6CB6 6CB6A 6CF6 6CG8A 6CN7 6CY5 6CY7 6CY7 6CY7 6DQ6A 6DQ6B 6EA8 6FM7 6GN8 6H6GT 6J6A 6J6A 6J6A 6S4A 6SA7 6SJ7 6SK7GT 6U8 6U8A 8FQ7 9A8 I'm thinking about making a small amp (below 5 watts) for my ipod, which one of these would be best?

Topic by guyfrom7up 10 years ago  |  last reply 9 years ago

boost volts deflate amps? Answered

I recently came to know about a "mintyboost" from "steveastrouk"( a very helpful and trusted member of instructables).It boosts up volts while bringing down amps very much like a step up transformer.Well I've got 2 AA rechargeable batteries rated 1.2 volts and 1900mAh.So here's my first question-I connect these batteries in parallel and they give out a total of 2.4 volts okay fine....but what about the amps?will they get added up like volts and produce 3800mAh current?The latter part-I need to boost this 2.4 volts to 5 volts by bringing down the amps(any value is fine as long as its above 0.7 Amps).Could you please give me a specificated instruction on how to do this?If to use a "mintyboost"what software should I use to calculate the required values and......... the rest...... Pls don't think I'm lazy.I really want to do this so badly...

Question by Adarsh_tronix 6 years ago  |  last reply 6 years ago

Slightly larger LED project.

Ok, so to start off I have done a few very small led projects before. And for some reason I decided I was going to up the concepts and baptismal by fire. Well to say the least I have a few questions. So all that read and help thanks! The Project:I have included a picture in very horrid crayola color to show you kind of what I am trying for. Essentially I am making a 6ft x 4ft robot head. I have built a frame (the picture) and there is going to be a spandex (or screen depending on what I decide) canvas with the bots head on it. What I want to happen is when I press the button (momentary contact) on the controller it activates the appropriate leds that light up a box. I will have at most 5-6 buttons pressed at once. Simple enough. The squares are going to have 18, 3mm leds. The colors are shown in the pic. I know that different colors require different volt, thus different resisters. The eyes are going to have 2 sets of 18 leds for alternating colors. There will also be 2 outside sets of lights to shine upon the face (18 leds also). "The Questions:"Well other than just asking HOW THE WHAT? I'm going to have this (or at least I want it to be) powered by one source. Maybe a 12v AC adapter. The problem is, is this enough? How many amps do I need to power 218 leds? I guess what I am saying is I know the basics but I need help with the electrical rating part of all this.

Topic by Foreverhex 9 years ago  |  last reply 9 years ago

20 watt PA amp transformers.

Today I bought a 20 watt PA amp at a garage sale for 5$, and there were 2 big transformers in there. Any ideas of what I could make?

Topic by mrbubl3s 7 years ago  |  last reply 7 years ago

How to limit amp draw of motors?

I am building an ROV that uses four thrusters, each can draw up to a maximum of 3-5 amps (motor says 3, website says 5 here). However, I will need to step up the voltage and I cant find anything that provides more than 10A continuous (currently using this but open to a higher amp option), so how can I limit the current the thrusters use in order to make sure that I dont blow out the DC-DC converter?

Question by OlliM1 3 years ago  |  last reply 3 years ago

My Amps! My Amps! *Screams an old crazy man in the deli section*

Yes yes, shhh I want to ask a serious question today. I traded one of my kenwood amps for my parents as their sony surround unit is really shitting out and the sound sounds terrible and the entire control panel on the front is messed up. I just want to know a couple things about the sony to see if I can fix something. The panel, well that's quite interesting to explain and if I posted a video of it you guys would probably think I edited it or something. So imagine this, the bass + and - buttons are beside the treble + and -, two sets of buttons. If you push one of the bass adjustment buttons, it glitches and turns the treble for example, up or down randomly and doesn't do what I wanted it to do. It's like this with all of the buttons and seemed to have happened after we moved here. And I know it didn't get banged around because it was transported in the back seat of a car on blankets to the new house and carefully carried in by me. If I say try to use one of the surround sound adjustment buttons it glitches out and acts like I hit another one that's beside it in any direction. Hard to explain but I'm just damn confused as to why it suddenly happend (dry solder connections?). Damn this post is long and it's only half Bad sound, I will not tolerate it under my household, but on the other hand it was a $400 unit back 5 or so years ago and I KNOW it used to sound good, with a such a profound richness of bass that just punched right through you. Now it sounds like shit, the sound is garbled, distorted when turned up, it's not really noticeable until you turn it up fairly loud. I have/had my technics tower speakers hooked up to it and they sounded like shit when I turned them up, yet on my kenwood they sing like the wedding singer days. Any ideas nachomoma? I'll add another note that for most of it's life it's been hooked up to a pair of 250 watt (peak) optimus floor speakers and whenever we played it, it got HORRIBLY hot and warped the top a bit when it was on, enough to push it in and make it spring back up again with quite a force. I liked this receiver a lot and would like to use it again, but I don't know where all these "degradations" came from and despite my useless amount of amp questions/bickering's about I would really appreciate any ideas from you guys. Thanks.. -Punk

Topic by Punkguyta 11 years ago  |  last reply 11 years ago

What is a 4 pin power connector that can handle a lot of current? Answered

For a project powering red, blue, and green LEDs, with a common positive, I am hoping to power around 250 LEDs with around 5 amps. This means that each wire needs to be able to handle 5 amps of current at 12 volts (or 60 Watts), with the other three wires acting as grounds. I've looked at PC peripheral molex connectors, capable of handling around 5-8 amps however that is over all four wires. I need something stronger, most molex connectors use 20 gauge wire (which handles 1.5 amps), while the national electrical code suggests a 14 gauge wire to handle 5.9 Amps. It doesn't matter to me what the connector is supposed to be used for, if it's an audio plug, power plug, or whatever, this project will be very jerry-rigged. I would greatly appreciate any suggestions for a suitable plug.

Question by QuackMasterDan 9 years ago  |  last reply 9 years ago

Problem with Led circuit, What's wrong?

I have 12 blue leds wired in parallel in 2 groups of 6, one of the groups work just fine while the 2nd won't light up at all. Using a 5 volt power source when I tested the 2nd group with a volt meter only .5 volts was going through the circuit. I tested each led individually and none of them will light with the same result of .5 volts. I'm out of ideas and have no clue what's wrong with it. Seeing as how both groups are wired up the exact same and one works perfectly while the other a complete mystery.Edit : My project is very similar to, all the wiring is basically the same set up.

Question by slayer04 9 years ago  |  last reply 9 years ago

If i make 5 LM1875 circuits, and put them in series, will i have 100 watts output power? Answered

What i mean is can i set it up like: audio source> input amp 1> output amp 1> input amp 2> output amp 2, etc... will there be around 100 watts ant the output of amp 5? Also can i use the same power supply for all 5 and put the voltage inputs in parallel? (i.e. the 5 Vcc's in parallel with the positive output from the power supply, 5 Vee's in parallel with the neg of the power supply) heres the national semi page for it: for some reason this doesnt work, can someone link me to a ~100w solid state amp, preferably something simple like the lm1875

Question by tigerdog330 9 years ago  |  last reply 9 years ago

How do I start my Arduino going?

Hey guys I just got my Arduino Uno and I'm not exactly sure how to power it up using the jack. I now know that I can run it off of the USB cable but how do I hook a battery to it? I've heard that your supposed to use 5 volts, but I don't see how I can get 5 volts. I only use AA and 3v and 9v batteries. So, also, since it can run off a USB port, I'm assuming I can use my phone charger to hook up the USB to it? Isn't it all 5.1 v? Well, please help me out and tell me if how many volts mA the board needs, which is too much and which is to low.  Thanks guys!!! ~electricloser

Topic by HavocRC 6 years ago  |  last reply 6 years ago

Aurora 9 bar Kit & Custom PCB for Sell

Aurora 9 bar Kit and PCB are now available for sell. ******* Prices are reduced ******* Aurora 9 bar custom PCB price is $7.50 + $2 shipping for US address. The kit is also available at $25 + $5 shipping for US address. All parts except Molex connectors and power supply are included. Kit Contents (as pictured) 16x 120 Ohm (0603) 21x 1k Ohm (0603) 1x 10k Ohm (0603) 2x 1uF (0603) 1x 10uF (1206) 1x AP7333-33 or AP7313-33 (3.3V linear voltage regulator) 3x MMBT2907A or equivalent PNP transistor 12x MMBT2222A or equivalent NPN transistor 1x PIC24F08KA101 (SSOP) 10x 5mm Tricolor LED (common-cathode) 1x 5-way Tactile Switch Notes The PIC microcontroller is not pre-programmed. You need your own programmer to program the PIC microcontroller. The kit is also available with water clear LEDs instead of diffused type shown. Please specify if you want water clear LEDs (Special: $1 less for the water clear LEDs). The kit comes with one extra LED. Power connection cable (see the picture) - optional is available at $2 extra. (International shipping is $17) To place an order, please go to my blog page - You will find purchase buttons. Please view my Instructable for the detailed information on Aurora 9 bar. Contact me if you have any questions. <br>

Topic by ledartist 7 years ago  |  last reply 7 years ago

How do I know what size breaker to use for 12 volt 5 amp/hour SLA ? Answered

I found a 3 amp snap in circuit breaker.  It says 3A-32V.  Does that mean 3 amps up to 32 volts or 3 amps at only 32 volts? The guy I bought it from wasn't sure.  He believed the volts could be anywhere between 1 and 32  and would flip the breaker at 3 amps anywhere in that voltage range.  In other words, 2 volts at 3 amps flips it, 12 volts 3 amps flips it , 24 volts 3 amps flips it, etc.  Is that how breakers work? Sorry about the backwardness.  I took the pic with my mac.

Question by Noblenutria 8 years ago  |  last reply 8 years ago

What value resistor do i need to make 24v 2.48 amps 22.5v?

I have 24v and 2.48 amps i need 22.5v what value resistor should i use? also could you show me how to get the answer i love learning about electronics I am using this to power 5, 5mm leds that operate off 3lr1130 button cells each

Question by DELETED_cdousley 9 years ago  |  last reply 7 years ago

Best, cheapest way to utilize a 10 volt, 6 amp solar panel?

Hey Instructables friends! So I have 20 solar cells that are .5 volts each and 6 amps. I plan to connect them in series to give me a 10 volt, 6 amp panel. I want to use the panel in my car to maintain the car battery and power my usb devices and be a general backup power source. The problem is that I am still new to electronics and I can't think of a cost effective, safe, and reliable way to utilize this panel. I need at least 14 volts out of the panel if I am to connect it to the car battery and even then I'm not sure how to limit the charge (I only want 1 amp maintaining the battery) and use the remaining output for other things. Any ideas are greatly appreciated! I also want to think of a free way to do this if possible.

Question by theFlash010 4 years ago  |  last reply 4 years ago

How to convert 120VAC to 90VDC @ .5amps?

Hello, I'm looking for a circuit the will convert 120VAC to about 90 VDC at .5 amps. If anyone could suggest a schematic or point me in the right direction of one that would much appreciated!

Topic by bigjohn412 2 months ago  |  last reply 2 months ago

What type of battery would I need to power 10m of RGB LED strips? Answered

For the summer, I would like to run two 5m strips of RGB LEDs in the cabin of my boat. I dont particularly want to run it off of the boat battery because I do not want to rain it while stationary. So my question is what type of battery, what specs, should I be looking for? Obviously a 12 volt battery because that is what the LEDs run off of, but is there a certain type I should be looking for, one that can handle the amount of amps the LEDs draw. Also if you could provide a link to a specific battery that would be helpful! The specs for the LEDs: Run off of 12 volts, (2) 5m Strips, approximately 5 amps per 5m -- so 10 amps total  Link to RGB LEDs:;=2YTJAFKDJWBSM&coliid;=I2PXDOU6G8R0XG&pf;_rd_m=ATVPDKIKX0DER&pf;_rd_s=desktop-1&pf;_rd_r=1PT4GDRNRM4JE2691CXW&pf;_rd_t=36701&pf;_rd_p=2079475242&pf;_rd_i=desktop All suggestions and help are truly appreciated!

Question by cobrien2115 3 years ago  |  last reply 3 years ago

Aurora mini 18 Kit and PCB

*** Back in of stock now!!! Thank you for waiting! *** The kit is also available at $29. All parts except Molex connectors and power supply are included. Shipping is $5 for USA, $17 for the rest of the world. Kit Contents (as pictured) 1x PCB 1x 10k Ohm (0603) 3x 220 Ohm (0603) 3x 2.2k Ohm (0603) 18x 150 Ohm (0603) 2x 0.1uF (0603) 2x 10uF (1206) 3x MMBT2907A 1x PIC24FV16KA302 (SS) 19x Tricolor LED (common-cathode) 1x Tactile Switch Notes The PIC microcontroller is not pre-programmed. You need your own programmer such as PICKit 3, ICD 2, ICD3 to program the PIC microcontroller. (PICKit 2 does not work) The kit is also available with water clear LEDs instead of diffused type shown. Please specify if you want water clear LEDs (Special: $1 less for the water clear LEDs). The kit comes with one extra LED. Power connection cable (see the picture) - optional is available at $2 extra. PCB only Aurora mini 18 custom PCB price is $9.50. Shipping is $5 for USA, $17 for the rest of the world. To purchase please go to my site - Please view my Instructable for the detailed information on Aurora mini 18. Contact me if you have any questions. <br>

Topic by ledartist 7 years ago  |  last reply 5 years ago

What would you do with five 5 v 75 amp power supplies?

I have these lying around and I know they are useful, but I'm just not sure how.

Topic by iculus 10 years ago  |  last reply 10 years ago

Arduino LM386 Pre-Amp for Mic ?

I am trying to (pre) amplify the signal from an electret microphone using an LM386. The output goes into the Arduino analog input 5. I have tried multiple circuits, but none of them succeeded. Either the value settles at some constant or its 0/1023 and even when its in the 500- 550 range, the value doesn't seem to be changing with varying sound levels. I tried these circuits: and a couple of more ones. I only have an LM386 on hand and cannot change it, as I need this to work out ASAP(in 2 days) for a science fair project. Hope you guys can help me on this. Kabir

Question by mhkabir 7 years ago  |  last reply 7 years ago

Solar panel maxes at 1A, but expected 3.6A?

I ordered a DIY kit from amazon. They are super flimsy and easy to break, but I was careful. Each cell was supposed to be 1.8W and .5V, ergo 3.6A by the math. But all put together now (in series) I get 5-5.6 Volts and about 1A max (with meter leads directly on each panel terminal). Voltage seems right, but current seems low. I'd expect somewhere in the area of 10%-15% over/under the estimated max, but this seems very wrong. I am guessing one panel in it is bad or cracked and I can't see it, and is limiting the whole deal. Does that sound right? Can I test the panels using the volt meter on the in/out leads on each cell, or do the other cells interfere after they're connected?

Question by Phoenix17 4 years ago  |  last reply 4 years ago

help! modifications on a vintage pre-amp Answered

I found a working pre-amp inside a turntable from the 60's. The turntable was scrapt, so I remove the pre-amp from inside. Now I want to put it inside a vintage radio wooden box, the problem I got, 5 potentiometers on the pre-amp, but I need to modify this so it will only have 2, becuz the radio box has only 2. I will use an iPad with this pre-amp, so there really no need for extra audio adjustments like treble or bass... So one for volume, the other for open and close. How do I modify the circuit of this pre-amp so there will be no sound problem ? Do I remplace the gradable resistors with a standard value resistor, if this is how to do it, what value should I use ? I've done some tests, if I skip the potentiometer and I'm getting too much static. I' would appreciate help on this! thank everyone !

Question by sebdub 5 years ago  |  last reply 5 years ago

8 Watt Guitar Amp Help

I've been fartin around with electric and acoustic guitars for about the past 5 years. Only now am i getting decent (by no means good, but better, i guess...). I've been wanting to make a small amp with a small speaker for some time now.I saw this circuit the other day. Its VERY simple. says to reverse the values of R1 and R3 for use as a guitar amp. there's some other stuff too. I was going to see if i could pick the stuff up at radioshack tomorrow, and maybe make it an after-work project for the week. Maybe cut up some wood and make a nice box for it. 1)Do you think these parts would be available at radioshack? and what do i need to look for if i cant find the exact IC? 2)Any special soldering tips? 3)What kind of pot do i need to add, and where, for a volume knob?4)Is there any extra things you think that needs to be added?5)Are those triangle things grounds? as in 12v negative? And what about the other wire from the guitar? 6)Also, what ohmage speaker do i need to use? What am i looking for in a speaker?7)Will 8 AA batteries do the job?8)Do i need to add like a fuse or something somewhere? Going straight into the IC...i dont know. If anyone knows of simpler or better designs, let me know. I seem to really [insert proper four-letter word here] up electronic things. I think thats all the questions i have here. To respond you can just go like..1)i think that. Hopefully that will make it easier to answer all my ignorant questions.Thank you!Jason(sorry if i seem like a a$$ here. Its 1:35am, I've been looking this stuff up for two hours, and i dont feel like i got any further....)And since i dont have a suitable picture, have yourself a look at my LEGO steam engine: (after the third try of trying to post the video with unsuccessful results, i realized that i was posting the embed code int eh URL place...need....sleep....)

Topic by John Smith 10 years ago  |  last reply 10 years ago

Arduino Multimeter on 1602LCD? Answered

Hi I am currently in the process of finishing the code for my Arduino controlled PSU with an LCD volt and amp meter. My question was basically, how can I get the volts and the amps to show on the LCD with 3 decimal place digits instead of 2 which i have now. Also, im having trouble putting 4 measurements all on one display- i currently have watts, amps and volts but i wanted to add resistance, however, for some reason i cant fit them all in one screen and i get weird errors when i try changing the setCursor value.  Thanks P.s here is the code I'm using (a took bits off different websites and examples-will reference them in the final sketch) #include const int numRows = 2; const int numCols = 16; LiquidCrystal lcd(12, 11, 5, 4, 3, 2); int analogInputVolts = A0; //voltinput int analogInputAmps = A1; //ampinput float vout = 0.00; float vin = 0.00; float amps = 0.00; float watts = 0.00; float ohms = 0.00; float VA = 4.970;          // Arduino 5V supply float R1 = 2995;        //  R1 in ohms float R2 = 999;        //  R2 in ohms int readAmpsADC = 0; int readVoltsADC = 0; void setup(){   Serial.begin(9600);   lcd.begin(16, 2);    pinMode(analogInputVolts, INPUT);    pinMode(analogInputAmps, INPUT);    delay(500);                    } float fmap(float x, float in_min, float in_max, float out_min, float out_max) {   return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min; } void loop() {    readVoltsADC = analogRead(analogInputVolts);    readVoltsADC = readVoltsADC + analogRead(analogInputVolts);    readVoltsADC = readVoltsADC / 2;    vout = (readVoltsADC * VA) / 1023.0;    vin = vout / (R2/(R1+R2));     delay(100);         readAmpsADC = analogRead(analogInputAmps);    readAmpsADC = readAmpsADC + analogRead(analogInputAmps);    readAmpsADC = readAmpsADC + analogRead(analogInputAmps);    readAmpsADC = readAmpsADC / 3 ;      // get average of 3 readings    amps = fabs(fmap(readAmpsADC, 509.0, 699.0, 0.0, 5.0));    if (amps < 0.09) amps = 0.00;    if (amps > 5) digitalWrite(13, HIGH);    delay(100);    if (vin < 0.5) vin = 0.00;          watts = vin* amps;    ohms = vin / amps;    Serial.print("Resistance-Ohms:");    Serial.println(ohms);    if (amps = 0.00) Serial.println("Nil");          lcd.print(" ");    lcd.print("V:");    lcd.print(vin);    lcd.setCursor(1, 1);     lcd.print("A:");    lcd.print(amps);   lcd.setCursor(0, 0);      lcd.print(" ");    lcd.print("W:");    lcd.print(watts);    lcd.setCursor(7,0);       delay(400); }

Question by lightemmitingdiode 5 years ago  |  last reply 3 years ago

10-15 AMPs w/ potentiometer.

So, as a chemist I thought it would be fun to save some $ by making my own hot plate & magnetic stirrer. I am using Thermoelectric cooling device (TEC) to heat my stirrer, and a small DC motor to stir. Here's the problem - if you've ever taken highschool chemistry you will know that a hot plate with a stirrer has a potentiometer for Temp & Stirring speed - I'd like to do the same! Problem: the TEC takes anywhere from 5-20 amps in operation @ 12 volts DC. Adding a potetiometer to this in parallel is out of the question - I can't fine a potentiometer that can handle greater than 2 watts. ( i may just be looking in the wrong place)... So.. all in all I'm looking for nearly 140-170 watts of power for my heating plate. (The motor will be using much less, almost negligble to the heating plate) So, if I can't put a potentiometer in series for power regulation, how can I get my temperature to vary? If this is going to require a circuit board, I may need some help with a design :)

Topic by GreenD 9 years ago  |  last reply 9 years ago

Powerbank has 3 USB outputs 2x2.1A and 1x1A all 3 are 5v, Can I power a small audio amplifier with these connected...?

Hey  Powerbank has 3 USB outputs 2x 2.1A and 1x1A all 3 are 5v, Can I power a small audio amplifier with these connected in series, or would they all need to have the same amount of amps? I currently run the audio amplifier off of 2x9V PP3 batteries, but these run out of charge too quickly and I'm am trying to see if I can run the amplifier off of a 50,000 mAh portable powerbank? I also have another powerbank with 2 USB outputs 1 x 1A and 1 x 2.1A (both at 5 volts) should I just run the amplifier off of the 2 x 2.1A outputs and the 1 x 2.1A output of both powerbanks connected in series, or is it fine to connect all three with the power bank that has the 3 USB outputs (50,000 mAh)? Thanks in advance

Question by MrShauny 3 years ago  |  last reply 3 years ago

Variable Constant current in micro-amp range? Answered

Would like help with finding a IC that can be controlled directly or indirectly using an arduino.  It needs to go from 10 microamps to about 200 microamps. I have a 5 volt power supply. Is there an IC for this, or how should I do it. I couldn't find anything on google that i understood. Thanks.

Question by headslant 2 years ago  |  last reply 2 years ago

LED Wiring, Over Amp Burnout? Answered

Hi everyone, hope someone can help? I just started playing around with some LED lights, trying to make a really bright Flounder light that can last at least 6-8 hours on the supplied battery. I was told if I used a "step-down", I wouldn't need resistors, (since the step-down does this in an essence), which I haven't, But the step-down keeps burning up? Here's the set-up I've been playing with... - 18vdc (power drill) battery. (unknown amps). - Step-down driver.... input 8vdc - 36vdc, output 1.5vdc - 36vdc - 3w LED Cree :                            ~ Reverse Voltage: 5.0 V                           ~ DC Forward Voltage: Typical: 3.8V Max: 4.2 VD                           ~ DC Forward Current: 700mA                           ~ Luminous Intensity: 170-190lm                                                           I use a volt meter to tune the Driver to a constant 4vdc to drive the LED. And the driver burns up and then the bulb after about 5 minutes. I was told I needed to add Ceramic Resistors, between the driver and battery, and between the driver and LED. (But what size?) I was also told I don't need extra resistors because of the driver? Which is Right? Or should I just add resistors between the battery and LED and do away with the Driver completely? Also, what is meant by "Reverse Voltage"? I have a 6vdc battery with a 4.5 amp capacity. But I want to use the 18vdc battery longer use, time wise. This is why I have the Driver, when 1 battery deletes, hook up the other one. I'd like to put 3 - 3w (180L) LED bulbs together, and run them off the 6vdc and/or the 18vdc battery so the LED's will last for at least 6-8 hours on 1 charge. I want to use either the 6vdc and/or the 18vdc battery because they are lightweight. I could go with 1w LED's so long as I can get the brightness needed to light up a distance of about 12' underwater to see a Flounder, and get 6-8 hours usage. Any help would be appreciated.

Question by Atomizer 7 years ago  |  last reply 6 years ago

Please explain WATTS to me! Answered

 I know watts equal amps times volts. But why? What is the benefit? Hypothetically, I wanted charge a laptop with some batteries ( instead of with the charger cord). The charger cord says 65 watts or some such, but what does that tell me?  Is 65 watts the same as 13 volts at 5 amps? Or 13 amps with 5 volts? what voltage/amperage would I need to charge this laptop? Thanks!

Question by nepheron 9 years ago  |  last reply 9 years ago

What fuse to use or breaker for a 12 volt 5 amp/hour sla battery? Answered

What size fuse would I use for a 12 volt 5 amp/hour sla battery.  Better yet, are there breakers for same battery.  I am wiring an electrical system for a bike.  As the complexity increases I accidently short the battery more often.  

Question by Noblenutria 8 years ago  |  last reply 8 years ago

How do i make a 1 amp boost converter that converts between 3-5v to 5v?

Hey, so  have been buying pre built boost converters but i wanted to build my own, my question is, how can i make a step up boost coverer circuit that takes between 3 and 5 volts and converts it to 5 volts at 1 amp. In you answer could you explain what each part does? Thank you!!!

Question by jbdawinna 4 years ago  |  last reply 4 years ago

How to wire small solar cells to increase voltage?

I need 10 solar cells that each produce .57v and .4 amp to be wired together to produce 5 v and 4 or 5 amp. (Series? Parallel? I just can't understand them very well!)A simple drawing would be the best :)Thank you all soooooooooooooooo muchSolved! Thank you for the help! here is a diagram of my solar charger (from what i learned here)

Question by nepheron 9 years ago  |  last reply 9 years ago

does anyone have a schematic for a smokey guitar amp/

I've herd the sound and realy like it but just cant bring mself to spend 30 dollars or more for a circut I cold probable make for under 5. Also, has ayone gotten one of those Vox AC30 headphone amps? I'd like to make one of thos too

Topic by spike shadows (secret agent man) 11 years ago  |  last reply 11 years ago

Would this solar panel charge a USB mp3 player? Answered

Could this solar setup charge an MP3 player? I can't see why it wouldn't, but I don't want to be missing something important...? With .275 amps it will charge slower than with .500amps ?(right?) Would .1v and .1amps charge a battery that needs 5v and 5 amps? Would it just be a slower charge or would it not charge at all?

Question by nepheron 9 years ago  |  last reply 9 years ago

Help choosing a genral purpose mosfets to buy in bulk? Answered

Hi, I am looing at buying  some mosfets in bulk. I need a mix of genral purpose N-channel annd P-channel mosfets. These have to be able to handle up to 40V and around 5 amp. These will be used for genral motor controlling and inductive loads. But mostley for prototyping. I need a mosfet that is cheap, takes a bit of a bashing, robust, and easy to use. Any suggestions on what I should get. I need both P channel and N channel mosfets for genral use. Thanks for any help, David.

Question by David97 6 years ago  |  last reply 6 years ago

Current limiting for around 10 amps at 12 volts for electrolysis cell? Answered

I am running an electrolysis cell off a modified ATX computer power supply. If I run the cell of 12 volts it will draw around 20 amps which is more than the power supply can handle and causes it to shut down after a few seconds. If I run the cell off the 5 volt port it only runs at around 2 amps, well below what I was hoping to get the cell to run at. Does anyone have suggestions to limit the power to around 100 watts (8-10 amps at 12 volts)?

Question by danlab 9 years ago  |  last reply 9 years ago

Do Amperage Ratings Add in Parallel or Series? Answered

I was wondering if the amperage ratings of devices, say, for instance, circuit breakers, add in parallel or series. For example, if I hooked up 5 20 Amp circuit breakers in parallel, would it take 100 amps to trigger them all? Or would it take 100 amps with them in series to trip them all? I'm not sure about this because I have used two 1 amp solid state relays in series to switch loads well above 1 amp, but it seems more logical for them to only do that if they were connected in parallel. Also, whatever the answer to my question is, does it apply to all devices? Circuit breakers, Triacs, etc? Thanks!

Question by mad magoo 9 years ago  |  last reply 9 years ago

Is there a 5 Amp ~35v equivalent to the LM-317T Voltage Regulator? Need to build 100w LED driver

Right now I'm running a 10w LED with a simple LM-317T & 1.8 ohm resistor combo. I'm looking to get a 100w led and build a driver for it. Is there a voltage regulator I can buy with these specs, or does this cheap "hack" only go so far? LED Specs: 100w 28-32v VF 3200mA IF

Question by Fuzzy3D 9 years ago  |  last reply 9 years ago

How to make a battery powered 5.1 speaker system?

Hi, I was wondering how I would be able to make reasonably powerful MP3 speaker system which is battery operated has 5 speakers( two tweeters, two mid range and one sub)? What sort of amp, circuitry and parts would I need? I was thinking about using amps like these...;=46809&doy;=24m7Thanks.

Question by 10 years ago  |  last reply 8 years ago

If I cut an LED strip that requires 12V and 5Amps, can I use a Power supply rated 12V 2.5A? Answered

If the strip is cut in half will the strips still require 5 Amps power supply or can I use a LED power supply that is 2.5 amps 12V ?

Question by DanTheDqMan 5 years ago  |  last reply 5 years ago

How does the num. of turns & voltage on the primary translate to an ideal voltage on the secondary?

In electronics, one of the things that has been the most confusing to me is the physics behind transformers. I have learned of that stupid formula a while back, where the ratio of turns is proportional to the voltage ratio and inversely proportional to the current, however, I know from reality that it is no where near that straight forward. As far as I can tell, it is a bunch of BS. Anyway, I want to know what the REAL story is, how the AC current going through the transformer is related to the magnetic flux through the core, and how that relates to the output of the secondary. What seems counterintuitive to me is that more windings on the primary should yield to a stronger magnetic field in the core for a given current, which means for magnetic flux (???) which seems like it should yield to more induced current in the secondary. Is the answer related to inductive reactance (more turns = more inductance = more inductive reactance = higher impedance at a given sinusoidal freq. = less current per unit of voltage?) Note: If you have a good physics and calc background and understand it to heart, pls do explain. However, I am currently only nearing the end of calc 2 w/ absolutely no formal education in physics, so I may have some difficulty with wank terms and vocab. (a.k.a. do not try to show off how many terms you know attempting to explain things in the most complicated and technical way possible.) Also, any good tutorials online that go into depth into the topic? ----------------------------------- The reason I want to know these things is that I wasn't to build a good 6A 0-+/-15V dual isolated channel linear power supply with many transformer tabs so I can keep the voltage drop on the pass elements as low as possible at variable output's so huge $$$ heatsinks are not necessary due to lower low power dissipation. (I have mostly figured out the LPS circuitry, but have not found a suitable Xformer online.) I can get the laminated magnetic cores needed relatively cheaply, however if I have to do some custom windings, I want to make sure I do not choose the wrong number of windings for the core. (obviously one turn on the secondary and 5 turns on the primary will pop a breaker @ 60Hz... )

Question by -max- 4 years ago  |  last reply 4 years ago

how to increase wattage/amp output of a power supply? Answered

Hey everybody im back with yet another question. I have here a adapter for a motorola cyber surfr wave, i intend to use it as a sort of pico psu, since it outputs 5v and 12v. the only problem is that I dont think it supplies enough current or amps to meet at least a 145w psu's equivalent. I would also like to know what resistor or voltage regulator to use to get 3.3v. the 145w supplies: +12v 4.2a +5 18a +3.3v 13a -5v 0.3 -12v 0.8a +5vsb 2a the unknown motorola supplies: +5v 1.5a +12v 0.75a does it need -12v, -5v and 5vsb for the computer to work? does a picopsu supply those? I just need to switch the main transformer with one from a decent psu right? then the wattage will be increased? If i cant, how can i make a picopsu? i cant order online and have a extremely limited budget. there is a picture of the insides as well

Question by zack247 8 years ago  |  last reply 8 years ago

Need a cheap dual-output, center tapped, 180VA 18V 5A transformer?

I am trying to design a nice dual-rail lab power supply and need a cheap dual-output, center tapped, 180VA 18V 5A transformer. The outputs are as follows: Primary: 120V Secondary 1:  9V-0-9V, @ 5A max. Secondary 2:  9V-0-9V, @ 5A max. ======================OR==================== Primary 120V Secondary 1:  9V, @ 5A max. Secondary 2:  9V, @ 5A max. Secondary 3:  9V, @ 5A max. Secondary 4:  9V, @ 5A max. I prefer a transformer for the linear regulator over a switching preregulator, because a switching preregulator sort of defeats the whole purpose of making a nice, high precision, low-noise lab instrument. However, I also prefer to have more than just 2 separate 18V outputs, since that means when the output is shorted and constant current mode kicks in for either the positive or negative rail, I will have a voltage drop of 18V, at a maximum current of 5A, and thats over 90W of power dissipation!!! I think that I can deal with that if thats the only solution, since I am planning on using a large CPU active heatsink for cooling, but I prefer if I was not pushing a TO-247 device to it's thermal limits. I have found this: It is affordable, but it seems strangely cheaper than a lot of other toroidal Xformers on the market. Also, the 2 primaries are not center tapped. It is 200VA though! I have never heard of that company, and it seems like the description of it is written in chinglish. They act like the fact that they over-engineered and under-specced it is a feature (to me, thats how all ratings should be, that should be normal and standard, not a feature.). I have also found this: It would be perfect, but it is $80!!! Very expensive, Also, I do not think it is a nice toroidal transformer, not that that matters much to be, I just like the professional look of a beefy toroidal transformer inside a power supply. Lastly, I have found this: It seems to be very similar to the first find, and it is from a reputable distributor. At $70 it is still expensive, and I do not want to spend over $100 for a homemade power supply. I would just get a off-the-shelf solution for that! What about the possibility of modifying a MOT transformer? How many VA or watts can I expect from the output without active cooling? I know they are rated from upwards to 1000W, but I also know they cannot sustain that power output for a long time without overheating and requiring lots of active cooling, and from what I remember, I believe the core is really being pushed into saturation during normal operation, leading to LOTS of power loss in the transformer core, but can they output 180VA continuously and effectively? Approximately how many turns of wire would I need to achieve my requirements, and what gauge wire should I use? I am thinking 20AWG but someone who has done that before would know better than me.

Question by -max- 4 years ago  |  last reply 4 years ago