Opposite of a resistor

So a resistor reduces the current, what would increase the "speed" of the current? Is there such thing?

Posted by jaketheman987 8 years ago

Reading resistors

I was just wondering if there is some kind of marking on a resistor that tells you which direction you should read it. I've seen brown bands on the ends of some resistors but not always, so I was just wondering if someone could help me out. Thanks Zealous

Posted by Zealous 10 years ago

3V Resistor and LED

What would be a good Ohmed resistor for an LED running on a 3V power source? 3.2-3.4V typ with a 3.8V max.

Posted by Brennn10 8 years ago

I need a 18 Ohm resistor

Does any one have a 18 Ohm resistor that they could stick in an envelope and send to me because eighteen bucks is a little steep for A resistor. oh ,and radioshack doesn't carry them either :( ~Matt

Posted by iman 9 years ago

Resistor negetive to positive?

Hey. I'm changing all the LEDs in the switches in the car. All is going well except one switch, there is 1mm distance between a circuit board and the LED. The LEDs are 12v no resistors. I'm using ultrabright red LEDs that need resistors. However, I'm sure I've seen circuits that resistors go on the negative and positive leg before the LED. Would this work or would the LED still blow? Thanks.

Posted by Josho 9 years ago

Hot, Burning Resistor Question

Ok....I have 24 leds in parralel attached to a 9 volt battery - and a 10 ohm resistor - as reccommended by LEDCALC.comLEDCALC.com - but, when i connect the circuit and hold the resistor in my hand, it becomes INCREDIBLY hot. Each led is in parallel, individually. So...is it normal for it to be that hot, or did I do something wrong?

Posted by Joe426 10 years ago


Please help me! I can't seem to understand the values of resistors and how they affect current and voltage. I have a 7.5 volt, 350 milliamp circuit that I would like to limit to 5 volts, and if possible raise the current to 500 milliamps. How could I do it?

Posted by jasper28 10 years ago

which resistor do I need for my LED?

What resistor is best for my single LED?  I've read that I need 1 Ohm (is that correct?), but I don't understand power watts and tolerance.  Could I get away without using a resistor at all?  Thanks. battery voltage: 3 diode forward voltage: 2.8-3.4 diode forward current: 20mA

Posted by aliasjanedoe 7 years ago

how many ohms does this resistor have in the led


Posted by dereklevine158 5 years ago

LEDs in parallel or series? One or many resistors?t

I want to make an LED strip, and I'm not sure weather to place two strips of copper down the side of the strip and attach the LED's to that, so it's parallel, or just make it series. What is the best? Should I use one resistor or many? (Obviously this only effects parallel) Thanks.

Posted by Josho 10 years ago

the right resistor?

Hey guys got a question. I want to add an ultra bright LED from my mini mag light to my atx benchtop power supply. The LED ran off 3v (2 AA’s.) The line I want to use is the 3.3v (14 amp) from the atx to power it. What size/power rating resistor should I use?

Posted by jmille38 7 years ago

Only up to four LEDs light up.

I've got loads of LEDs and resistors from eBay and using the resistors, only up to 4 LEDs in serial will light. I can't just use more resistors, as I broke open a mains lighting bulb that uses 20 LEDs to provide lighting. Looking at the printed circuit, they are all soldered in series. If I put + at one side of an LED and - at the other with these resistors I have, it lights, two three and 4 work, but on the 5th, it drops dim, after that it won't light at all. Do I need a different resistor, of is something else wrong. Could someone kindly tell my what resistor I need for 20 5mm White LEDs running off 18v (two 9V batteries), and 9v (one)? Thanks! Josh.

Posted by Josho 10 years ago

Homebrew heaters using resistors?

Hello, First time poster! :) I've been reading up on some projects on this site centered around small homebrew heaters. One I came across I want to adapt is using two resistors and usb port power to make a small coffee mug heater. I'm kind of a novice at electronics, but I'd like to know how to design such a heater with safety and functionality in mind. I also want to control this heater via arduino if I can get a prototype together. Some questions I have: Where to get and what kind of resistors for heaters? How do I figure out what resistors to use based on power. e.g. 12v or USB power? What's a good thing to "encase" the resistors with that will withstand heat? I have thought about using radiator repair epoxy. Thanks for any help!

Posted by Sylvester2009 8 years ago

Can I make a 15W+ 1-5Ohm resistor?

I'm making a yard sprayer with a 12V, 5amp pump.  It works great, but I'd like to add in a 2nd, slower speed setting for situations where I want less fluid going through the sprayer.  It needs to a be a simple fast/slow switch, not a variable resistor, since I need the flow rate to be repeatable and consistent.  Ideally, I'd like to make about a 2-ohm resistor, that would need to be able to handle about 15W.  Unfortunately, no local shops have anything like that, and I don't want to wait for an on-line order to get shipped. Is there any way to make a DIY resistor to roughly achieve these characteristics?  (Like I said, the important part is that it will be a consistent resistance value, not a specific resistance value, and not burn up with 2-4 amps going through it..)

Posted by SvdSinner 5 years ago

Help with voltage/resistor

Hello.  I bought some Christmas LED replacement bulbs but they have no specs with them.  I decided to wire one up.   I figured I would go with 1 . 5 volts at 7 1/2 mA.   Using a 9 volt battery, I have a 1K ohm resistor.   9 - 1.5 = 7/ .0075.  My problem is, when I put my meter on it, the one side of the resistor is showing 9 volts, correct, but the other side is showing 3.5 volts.   Shouldn't it only be reading 1.5 volts?  What is wrong?  *I've had the LED lit up for over 25 minutes so far and it hasnt burned out yet. Thank You. EDIT:   I just added  a 10K resistor, so now I have 11K (in series), yet I am still getting a reading of 3.5 volts.   I'm missing something here. lol   I'm also getting a reading of about 9mA with 1K and 11K ohms.   I'm lost.

Posted by pennsteve 8 years ago

Variable resistor problem..

Http://img86.imageshack.us/my.php?image=picture433pb4.jpgI ripped this out of a car audio system, i don't know the input volts, or whats what. I use to have it connected to a 3V battery to change a LED from 0 to 3V. Well, i pulled it out, wires gone. resolder wires as you can see. problem: WHAT IS WHAT?! All i know by the labels is it says RED on the lowest rail. the rest, dont know. If someone can please help me id love that. It switches on/off as well as changes volts. so i need 4 wires connected.

Posted by Killa-X 10 years ago

What is the best ohm resistor for LEDs?

What is the best ohm resistor to use with a standard led to ensure that it won't burn out? Is it 330? Thanks!

Posted by sciguy77 9 years ago

how do you know what resistor to use with LEDs

How do you know what resistor to use in a LED circuit? I salvaged a bunch of resistors,diodes capacitors and LEDs from several objects. how do i classify the resistors(i know they have different colors/sizes/stripes but what do they mean?)

Posted by ledzep567 10 years ago

Resistors for a project, easy question!

Hi all, This is an easy question about resistors, its been years since I use any. So, I have a replay which is rate 12v DC and 2amp. The power supply is 12v DC and 6 amp. V = I X R R =  V / I so R = 12 / 2 = 6ohm So I need a 6ohm resistor? Is that correct? I can't believe I have forgotten this! thanks Gary

Posted by garynobles 5 years ago

Configuring LED in a series, where do I place the resistor?

If I was going to a configuration of 3 LED lights (10MM), do I need a resistor for each or only for one? And if only for one, how do I calculate for the resistor I need, i.e., does the resistor need to take into account the output of each LED and multiply by 3? Very new at this, trying to learn as much as I can. All advice is greatly appreciated.

Posted by shindakaeru 2 years ago

LED wiring/resistor

I'm a beginner in understanding electronics so please bare with me. :) what kind of resistor should I use in lighting 4 LED's with 9 volts battery? I really need your answers. :) Thanks in advance :)

Posted by imatrianidar 3 years ago


I bought 100 leds of ebay a while ago and it came with 100 free resistors. What im not too sure about is what ohm they are. On the ebay page it dosent say if they go with the leds the shop specialises in leds and gives similar resistors with almost every order. All it says on the page is that there perfect for working with 12v or something. I tried looking at those colour code calulators but I still couldnt figure it out. I knew someone here must know. The colours in the pic arent great so I wrote what they are aswell.

Posted by flyer3 9 years ago

The rite resistor to charge this super capacitor.

    Hello I was wondering what resistor you guys would recomend for use in a capacitor charging circut. I can follow common sense for a small 160uf 300v photo capacitor. But this cap has a rating of 3,700uf and 600v. And considering its in issue, (which I believe it may be,) assume your giving it 18v of power from let's say... a drill battery.                                                      Thank you.

Posted by darthDIY 8 years ago

Which resistor do I need?

I am using DC current to power 4 computer fans. I have 3 fans hooked up now that draw out about 560mAh. I need to know what resistor to use to get 12V DC 1440A  down to 8V DC .25A. Please respond as quickly and informatively as possible. Thank you in advance. Note: I got the 1440Amps from subtracting the usage from what the AC adapter puts out. The AC to DC adapter I am using puts out 12V 2Amps. If you can tell me the model number, and/or colour code.

Posted by Wally_Z 7 years ago

Best resistor to lower my current?

Hi everyone, I recently started to get into electronics and now need some assistance. I have a 12v and I believe 1A of power. The component I'm connecting is 3.7v with a 450ma battery that uses 3W. I using a l78m05cp, I built what should be a 5v .5A psu, but I must have calculated something wrong because fried my component. I believe the current is what I'm not getting right. Using P=IV, I found I should be using .8A, but I really am not sure about it. Please help, I'll go broke if I keep frying things!

Posted by ramirez_armando 4 years ago

Help with resistor calculator for LEDs

Hi everyone, I decided to try and build some LED lighting and found a few online resistor calculators but, I'm not exactly sure what to put for the voltage drop and the LED current (other than using the generic suggestions from the online calculators). So here are my questions... Is the "forward voltage" what you enter for the "voltage drop"? If so, do you use the lower or higher number? For the LED current, do I use the "max cont. foward current" or should I just put in the suggested 20mA? what kind of a difference would one be over the other? These are the specs given for the LED I'm going to be using (minus the unimportant stuff). Forward Voltage (V) : 3.2 ~ 3.8 Reverse Current (uA) : <=30 Absolute Maximum Ratings (Ta=25°C) Max Power Dissipation : 80mw Max Continuous Forward Current : 30mA Max Peak Forward Current : 75mA Reverse Voltage : 5~6V Thanks in advance.

Posted by GSXR 8 years ago

Reducing current to drill

Hey everyone. I'm building a potters wheel for my girlfriend for Christmas, and for the motor I'm using a corded drill. I want to use something like a sewing pedal to control the speed, rather than the trigger of the drill. I've looked it up (on here) and it sounds easy enough, but the problem is that most corded drills are 4 amps and over, and the highest amperage I've found on a sewing pedal is 1.5A, I'm assuming this would blow up the pedal. Is there some way I could use a resistor to reduce the current drawn by the drill? Would the drill still operate on 1/3 the current? It won't need even close to full power. Where would this resistor go? Thanks in advance.

Posted by checkmyusename 4 years ago

Project Help

Hey everyone I was hoping someone could help me with a project that I'm working on. I'm relatively inexperienced with electronics so this might just be a simple solution, but here it goes. I have a 4.8V, .9A power source and I would like to connect the power source, a toggle switch, a LED, and a USB port in series. A pretty simple idea. I don't know too much about LEDs, but I do know that you have to use a resistor with it. And I've heard that the LED and resistor have to have a voltage drop equal to the voltage of the power source. My main question is this though: how can I use the LED along with the USB port? Will there be enough voltage left for the USB after the LED is lit? Thanks for any advice!

Posted by msh21 9 years ago

How to get 12 volts from 18 volts

How would i regulate 18 volts(2 9v batteries) to put out 12 volts instead? im doing this because 2 6v batteries is really heavy(im replacing 2 6v batteries, and they are also broken... dont ask how) thanks

Posted by ledzep567 10 years ago

peltier circuit board

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

Posted by Johnieahenderson 1 year ago

how to make a circuit board

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

Posted by Johnieahenderson 1 year ago

resistors and watts

I know how to use ohms law to calculate what size resistor I need but what I really need to know is how to tell/calculate what watt rating I need to use whether it be 1/4, 1/2, 1/8, 1,10 and so on.

Posted by pattyshaw 6 years ago

resistor Q

I'm building an LED circuit and I have the right ohm but the W is 1/2 when 1/4 was calculated out?

Posted by mrshow555 10 years ago

Resistor Calculator for electronic enthusiasts

Hi to evebody. I would like to share a tool which was developed for my own needs. For some time I recently need to obtain not standard resistor values with rationed precision from standard E24 series of resistors. Unfortuantely I don't find really good and convenient tool to do it. Finally I decided to made Resistors Finder for iPhone. I did my best to create simple, nice and convenient user interface and fast searching algorithm. Resistor Finder was just released yesterday on App Store. If you want a  free copy please PM me for promo code. Only 10 promo codes available. It will be nice to hear some feedback from you all. Any suggestion, critics and feature requests are welcome.

Posted by lyubomyr 6 years ago

Parallel Circuit question?

When connecting LEDs in a circuit in parallel, why do you need a resistor for each LED or LED series within the parallel. Couldn't you use 1 resistor connected to the power supply before the current even got to any of the LEDs in parallel?

Posted by mrshow555 10 years ago

led n00b here, need a little help

Hey guys i am new to electronics and figured id start with leds, my first project will be to make a torth from a penguin caffinated mints tin using some domestic batteries, some Super bright (17000mcd) 3v Green LEDs and 10 resistors only described as "Used to operate a 3.3v LED on a 5v Power Line. " and the same for the 10 12v resistors. now can anyone tell me. when would i need a resistor in my circuit? (i know the one for the 12v line would be perfect for arraching to a car battery and not killing the led.) but the 5v resistors? when would i use them? when i make this torch i will be using 2 or 3 aa batteries, 2 aa batteries make 3v and these leds are meant for 3.3 so im assuming i wont need a resistor however if i used 3 aa (4.5v) would i need the 5v resistor or would it be to much? im sorry im confusing thanks

Posted by Cew27 9 years ago

Odd Breadboard Question

Hi All  I am brand new to hobby electronics and would love one day to be able to create the endless amount of cool Instructables but I have ran into a problem on my first attempt at putting theory into practice and would really appreciate any help. I have made two diagrams / images showing the circuit I made I have attached them to this post. I am using an Arduino Uno as a power source.... I ran a 5v positive from the 5v pin on the Arduino using solid core jumper to the top of the breadboard onto the positive row / rail and a negative / ground jumper to the bottom of the breadboard. In the middle of the breadboard I placed a 1k ohms resistor bridging the gap / grove/ divide and ran the positive feed through it and on to the anode leg of the LED. The cathode leg of the LED was connected to the negative row / rail completing the circuit. All works as it should because of the high resistance from the resistor the LED barely lights and is green as it should be. So without using a multimeter I know and can see the resistor is clearly working. However if I move the resistor so it's still on the same line / row as it was but no longer bridging the gap the LED goes super bright and turns yellow which means that the resistor is no longer working which I can't figure out why because I know there is definitely current flowing through it given the extreme reaction of the LED. I vaguely remember reading somewhere on these forums that Fritzing is not liked very much so I hope no one minds but to help explain what I mean above I have created two diagrams / pictures using Fritzing. The images diagrams shows the resistor "bridging" and working and the other shows it not bridging and therefore not working. So my question would be why given the resistor has current flowing through it does it not work unless it's bridging this middle divide / gap / grove? It makes me think I am missing something really stupid that everyone should know about breadboards but just seems really odd to me. Many Thanks Rab

Posted by belfastrab 3 years ago

Vintage Headphone repair, help needed

I have some vintage Superex Stereophones, model Pro B-VI (with a google search only find an ad in a paper dated 1973 referencing them). They have both a tweeter and a woofer in each ear, and I believe the resistors in the crossovers have gone bad. The high end drops out now and then to pop back in after a short while or after a minor volume adjustment - other than that the volume is crystal clear. Am I right in assuming the resistors could be the issue? The other components in the crossovers are just inductor coils, which are know are for the low pass, so it can't be those. I know instructables isn't a electronics repair forum, but I wasn't too sure of where else I could ask and find knowledgeable people. I love this site. :) I.W.

Posted by incredibleweirdo 10 years ago

LED burnout

I've been having trouble with LEDs. I'm running 18 blue ultrabright in parallel. The specs for volts and amperage are as follows: 3.6v typ 4.5v max 20ma typ 30ma max Each LED has a 220 ohm resistor which was calculated for a 9v source with each LED at 4v, 25ma. This seems well within their range. But, in about a year and a half's time, I've had about 25% burnout. Most of the others are showing signs of intensity and spectrum degradation. Any thoughts as to the cause of this?

Posted by hexedene 10 years ago

Anyone Have experience with Adafruit Square FSR?

I am hoping to create a circuit that will variably control the speed of a motor through pressure. If I were to wire up one of these http://www.adafruit.com/products/1075 , simply as the switch between a small motor and a power source around 5v, would it work to simply turn the motor off at rest and vary the speed with pressure? Is there a way to use this resistor as a "switch" without using an Arduino or  other micro controller? Any help is appreciated. Thanks! 

Posted by Flashflint 3 years ago

Need Help With Battery Heating Elements!

I’m seeking advice on building a battery powered heating element, goal being 1300 degrees Fahrenheit.  I have a 4.8v 4200mah battery and Kanthal A-1 20, 26, 30 gauge wire, but am not limited to this material. The element will be a circle with a diameter of about an inch, similar design to a range coil.   Hoping someone can help me, feel free to ask any further questions.

Posted by HumanLightningRod 3 years ago

Calculate Resistor for Heating Wire

Hi there, My Goal is to use a piece of heating wire from an old hair dryer  (1.6 Ohms resistance for the length i want to use.) and heat it red-orange using my old USB power bank. 5V output from an 3.8V lithium ion battery i dont want to mess with the circuitry inside. Problem: The USB Power Bank has short curcuit prevention built in, so when i connect the heating wire the power bank stops supplying electricity. I found a 7.5 ohms resistor and connected it aswell, the wire became a little warm, the resistor incredibly hot but most importantly the power bank continued to supply power - success. I would like to know what resistor i should use to get the wire red-orange hot but at the same time keep the power bank safe and not overwhelm it - i think that would mean not drawing too much current? I also cant check how much current is flowing because my multimeter is too cheap and only goes up to 200ma, which the power bank exceeds. So how would i go about this? What resistor should i use for what wattage should it be rated. And since im a total newb id like to hear your train of thought as to why and how. Thank you so much.

Posted by emiliori 1 year ago

Connecting a Gameboy to my Mouse.

I got a lot of Gameboys, (I bough em cheap to do some hacks) My Logitec mouse uses 5V ofc. My Gameboy needs his 3V.   So far I have heard that I should therefore use a 200ohm resistor. The question is, can I hook the Gameboy directly into the Mouses powersupply? Or do I have to add a second usb cable for it's power? Also, do I even need the resistor?

Posted by Schoening 5 years ago

Resistance calculator using flash

I just created a resistance calculator using liveswif (its like macromedia flash only not as good) and programmed it with actionscript.   I can't figure out how to get the numbers to line up properly, although the calculator still works.   If you have a resistor and need to find out how many ohms it is, the calculator will do it.   http://www.gamesfree4u.com/resistancecalculator.html

Posted by pennsteve 8 years ago

Speaker + resistor = joy? - help a mom replace a $299 6.5" OEM auto speaker

Hi All, I come to my dear instructables seeking some basic understanding.  Let me just preface this by the fact that I have no problem getting dirty or cracking things open to try to understand them better- probably  better at taking them apart than putting them back together - but I try...(hubby kids that I always end up with spare parts too). this leads me to my current problem. The right front speaker in my 2001 sienna minvan decided to blow after much to much green day playing. Yesterday I just couldn't take the awful hissing anymore and popped off the panel to pull out the speaker. I'm kinda used to my old cars where I could pop down to best buy and pickup a new set. Not so with Toyota - OH NO they have special 2.2 Ohm speakers that are proprietary to Toyota. So I went to the dealsership and was told that a new right front JBL speaker replacement  (model 6689) was going to cost me $299. - you read that right $299 for ONE 6.5" door speaker. I found a website briefly outlining how to take a plain 4 ohm speaker, get a 1.8 Ohm resistor and be done with it.  -  http://oneilengineering.9f.com/photo5.html - So there are a few questions that I need answered by someone with experience. 1) Is it that simple?  - I may opt for decent replacements and I'll do both door ones so they match ... 2) I can't see from that fellows photos exactly how the resistor is attached - is it just soldered in place bridging the two end where the + /- leads are attached? any existing ibles with closeups? I couldn't find any. is a resistor directional? 3) I read somewhere that if I'm adding the resistor -  that heat will be generated from reducing the current - Is that true? if so - do I have to shield it somehow? Thank you for any help !!!

Posted by boarderline 7 years ago

LEDs at less than forward voltage ; no resistor??

I'm new to playing around with LED's, so please forgive the ignorance.  Right now I am trying to make a homemade lamp of sorts.  I am using white LEDs with the following specs per the seller. FW current - 25 mA FW supply - 3.3V (typical), 3.6V (max) Tested one LED with two AAA batteries and no resistor.  I was told by radio shack guy that since supply voltage was less than FW supply I would be fine, and the LED would pull the amperage it needed.  Lit up and looked fine to me. I then found a 9V DC wall wart, and decided I wanted to run possibly up to 12 LEDs using 4 parallel strings of 3 LEDs in series (9.9 volt drop across each series).  I bought a multimeter and checked the DV voltage from the power supply, and it ran consistently between 9.1 - 9.2 volts.  The thought with the 9V wall wart was that the voltage supply would be lower than the FW supply, thus I would not need resistors, simplifying and reducing # of connections needing soldering (new to that as well). My question is, will this 9V work for my system?  I've tested 3 LED's in series, and also 2 parallel strings of 3 LEDs in series, and both lit fine.  I've read posts where people say that the lights will not light up or will be dim if the FW supply is not provided.  As mentioned, they seem fine to me, and as this lamp is planned for more of a mood lighting, I don't need it much brighter.  Is the only downside a dimmer light?  Will it last just as long?  My main concern is putting the time and effort into constructing this thing, and then having the LED's fail for some reason I don't understand, and having to rewire it all.  I've thought about buying a 12V supply and using a resistor, but would rather not unless there is a good reason to do so. Thanks in advance for any input!

Posted by brumachine82 2 years ago

How should I regulate the power for my motors?

Hello, I am planning on building a stepper motor driver using Tom McWire's design. I want to control 3 motors which are rated for 7 volts, 350mA, and 20 ohms. I plan on using a 12 volt 5amp power supply. I am trying to figure out what kind of resistor I should use so that I do not fry my motors. Maybe I am missing something, but this is the way I am looking at it.... If the motor is using 7 volts and the power supply is 12 volts, that means i have 5 volts left to use. 5v over .35amps (the amount the motor uses) is 15ohms. (14.28 rounded up) That also means it uses 1.75 watts (5*.35). Would a 15ohm 2 Watt resistor be sufficient or am I looking at this all wrong? Thank you for your help in advance, folks :-D

Posted by TheLostAmish 9 years ago

how to make led cornhole light?

So I love playing cornhole and so do my friends.. so much we wanna play when Its dark but were to cheap to buy an led cornhole ring for 44 bucks.   I have a 9v battery holder and 6 white l.e.d.s (square with four pins), and 3 150k resistors. I have tried a few different set ups and nothing seems to work can please some one help me. Its my first go around with l.e.d.s so yeah I really have no clue

Posted by yababbadaba 7 years ago

Oscillator Help

Hello, I was wandering if you guys would like to help me out with a quite simple little project. I am looking at making a simple oscillator that could be pumped through a normal musical instrument amplifier. I'm not looking at using any IC's (555, PIC etc...), simply some resisitors and capacitors connected to a audio output and a Rheostat. So my question is this. An oscillator (in terms of electronics) is simply a electronic current that goes from one very high frequency to a very low one, right? So could a just use a fairly big capacitor and a very big resistor and would it be listenable through a speaker?

Posted by dipseydoodle 6 years ago

Protecting my new power supply

I've got a 12vdc 500ma power supply that I'm using to trigger a few solid state relays. I'm also using the same power supply to provide input current to a little micro PLC (Automation Direct DL05). Both the relays and the PLC have a wide range of acceptable input voltages and their current requirements are about 15ma per channel at 12 volts. The count is 6 relays and 8 PLC inputs, if all are on thats about 210ma. I once killed a similar power supply by allowing the leads to touch and short-out. I would like to protect this power supply from the same fate by protecting it from short circuit. I thought about attaching a reisistor to the end of one lead and covering all but the outlet of the resistor with heat shrink tubing... problem is, it would have to be a big, bulky power resistor to handle the wattage. Is there a simple component available that will limit the current upon short circuit that I can place in series with my loads to protect the power supply? As I said, it doesn't have to be precise and it doesn't matter if it jerks the voltage around a little.

Posted by fluoronator 10 years ago