Search for resistors in Topics


For people who don't know, how do you connect a resistor to a LED light?

Topic by liketoblowthingsup48    |  last reply

Resistors? Answered

I'm trying to do the evaporator workaround for the Ford Fusion. Instructions from this page say to use 37kOhm 1/8 watt resistor. No one has this. Can I use other wattage rated resistors such as 47 kOhm 1/2 or 1/4 watt ?

Question by DaleH48    |  last reply


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?

Topic by jasper28    |  last reply


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.

Topic by flyer3    |  last reply


How many ohm resistor would i need to resist 7 volts to 3.5 volts and 12 volts to 3.5 volts also....

Topic by Yerboogieman    |  last reply


Ok, I want to have a thing where ive got a battery pack, and then 3 toggle switches and one button switch, each one that is flipped/pushed lights up an LED and then the last one (button) lights up both the led and powers a small hobby motor or something like that. My question is, What do I need resistor-wise? (quantity, location, strength..) Thanks!Amendment I want to have the same idea going, but kind of have an extension cord running through it, so I plug the box in, and then plug something into a cord coming from the box.

Topic by Weissensteinburg    |  last reply

resistor id?

This might sound stupid, but being brand new to electronics i need to pose this question, i found a scematic with 3 resistors on, 1 is a variable rated as R1 100K, the second R2 1K, the third R3 270R, the problem is the third resistor, what does the "R" stand for?

Question by nicobotha12345    |  last reply

WTF resistors

I just got a back of about 130 resistors for a bag of 50 L.E.D's but some of the resistors ive never heard of, there are a few like 100ohm and 560 ohm but now im getting 1m ohm and 4.1Mohm and 100K ohm,1.5K ohm and 1K ohm. Ive never seen resistors like this before, i am very basic in electronics but i took a class at school have have made many many projects but never resistors like this and i only wanted to use them for a few L.E.D's, I dont really know what im asking for in here but i just sapose if anyone has any help or ideas or really anything with these resistors and matching them with L.E.D'S?

Topic by craig3    |  last reply

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

Topic by Zealous    |  last reply

LED Resistors

I`ve been searching around everywhere about Resistors and how to use them, I understand that they resist power to the LED light t to a safe limit, but I need a noobs guide on how to use them, can someone help me?

Topic by Alcreion    |  last reply

Resistor value?

I'm making the circuit attached, can anyone help me with what resistor value (marked by "?"). What value will need when I connect 2 UV LEDs into the circuit. The pack says LEDs are 3.1V. Any help would be greatly appreciated...

Topic by Lee Fraser    |  last reply

Resistors and speakers

Hi, Is it possible to create a 16.5-17Khz speaker output using only resistors? or should I look into a 555 timer? if so, how? Thanks, Dan

Topic by danward    |  last reply

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.

Topic by pattyshaw    |  last reply

LEDs and resistors

I notice a lot of people tell you to always put a resistor on an LED. Should I use a resistor if my LED's forward voltage is the same as my power supply?

Topic by bomberman3    |  last reply

Opposite of a resistor

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

Topic by jaketheman987    |  last reply

resistor parallel

Sir I need 100ohm 3 watt resistor but cannot find it in market, in market I find 100ohm 1watt resistor ,plz tell me how I acquire (100ohm 3 watt resistor) value. can I parallel three 100ohm 1 watt resistor to get my value

Question by robinhoodxx    |  last reply

Resistors and capacitors Answered

Can any one tell me how can we use and install resistors and capacitors? And how can we study the resistors and capacitors

Question by k.bipin    |  last reply

solar resistor

What reading solar resistor should i use for transfering sound on a laser for my project?

Question by Aditya3870    |  last reply

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?

Topic by mrshow555    |  last reply

Is this a fuse or a resistor? Answered

I have been having difficulties with a PSU construction for a formerly battery driven (unknown amperage, 18 v ) electric drill and first needed help in identifying a part; picture included:  

Question by Goodhart    |  last reply

resistor replacement

 I have a small model battery charger which has a resistor burnt out . output is 7.5  volts  according to the label which sounds right as pack is 7.4volts.  measured voltage from transformer  is 15 volts Can anyone tel me what value resistor I need to drop the  voltage  to 7,5 v or whatever the actual out put shoul be. thanks people, john mantova

Topic by john mantova    |  last reply

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?

Topic by jmille38    |  last reply

Resistor Heatsink? Answered

Hi Guys,   I built a power supply (half wave rectifier) for a project. It simply rectifies normal 120VAC and gives me a pulsed 120VDC output. The resistors are rated for 20 Watts (I calculated that I only needed 4.32 Watts), but they still seem to get extremely hot and I think they are beginning to break down. Is there any way I could put a heat sink on them? Thanks

Question by transistorguy    |  last reply

Resistors power and tolerance?

I am relatively new to electronic projects building and I have noted that some projects do not state the power and tolerance of the resistors. How should I proceed, are there any guide lines to establish the tolerance and wattage? Thatnks.

Question by ajax70    |  last reply

What size of resistors should I use? Answered

I'm going to build an 8x8x8 LED cube and I am confused about what resistors I should get. Here is a link to the blue LEDs that I bought: This step says to use the burst load of the LEDs but the chart on the item page is somewhat confusing to me. I know that with the resistance equation it would be R=3.2v/0.02A but I don't know if that is the right mA. I am pretty new to electronics so any help is appreciated.

Question by Arya42    |  last reply

Ohm's law is calling for a 50ohm resistor. Could I use two 100ohm resistors in parallel or would that be too close? Answered

I'm trying to teach myself resistors through a LED project. My LED's typical FW voltage is 3.5 under a 4.5 supply voltage and a FW current of 20mA. If I've done the math right I should need a 50ohm resistor. correct? I'm hoping to buy the resistors from Radioshack and looking at there supply they only have resistors ranging from 48ohm to 68ohm. I know I could just use the 68ohm resistor, but have also read that wiring resistors in parallel will reduce the resistance. So using two 100ohm combined should work. It just seems too simple and close to Ohm's law's outcome. Would this be safe for the LED?

Question by GodCent    |  last reply

If you place a 1 ohm resistor across a 12 volt car battery, how much power will it dissipate? Answered

This is one of the exercise from the book, "The Art of Electronics." They do not give answers and i wanted to know if i did it right. I got the answer of 1.44 watts, but i am not sure if this is correct.

Question by cooldude01    |  last reply

How do I figure out what size resistor I need to slow down a recycled printer motor down to it's absolute slowest speed? Answered

The motor will be driving a small belt and a paper towel tube. This project is for Halloween. I'm trying to create a mechanical fade circuit for a fluorescent tube. The motor came from an old printer and runs at full speed when 12v is applied. I want to get the motor down to a speed where the tube rotation is as slow as possible.

Question by javajunkie1976    |  last reply

How to calculate the equivalent resistance of this circuit? Answered


Question by ubdussamad    |  last reply

Finding the wattage rating of resistors and variable resistors? Answered

Is there a way to find the wattage rating of resistors and such mathematically? or is it something that has to be tested in real life? I have quite a few resistors that I'd like to use, but don't know the wattage rating of them. I only know their resistance, and I could calculate other values if I put voltage across them with a multimeter.  Also, what type of variable resistor would you recommend to control a 12 VDC device that draws 12 amps?

Question by tylervitale    |  last reply

how to organize resistors?

I need some help organizing resistor. i have a ton of resistors but have no idea how to organize them. any ideas?

Topic by DELETED_kclv1988    |  last reply

Question about Resistors Answered

I have am writing an arduino sketch for a mini traffic light projects that will require both 220Ω & 330Ω resistors, I ordered them, the problem is that the resistors I received don't add up when looking at the bands. this is the color band  ORANGE+ORANGE+BLACK+ORANGE+BROWN 3 -------------3------------0----------x3------------1%-------- does not this mean 330 x 3 @ 1% so the 330 is actually 3,300 or would it be 330kΩ It's been years since I've looked up color bands , can I even use these ones for simple 5v led projects or should I just re-order the 330Ω resistors now? thanks in advance robert  

Question by rdlockrey    |  last reply

Resistor Colors Confirmation

 Hi, I got a bunch of resistors with my LED order, and I'm having a hard time with the colors on this set. The picture actually shows it clearer than I can tell with my eyes. So what is your verdict of them? 70?

Topic by Justinph5    |  last reply

Are resistors need with mosfet?

I posted a very similar topic a couple minutes ago but I'm pretty sure noone can see it, so I'm copying and pasting the body. I just want to check this before I blow up my mosfet (I've never used mosfets before) Is it correct that you don't have a resistor from the voltage source to the gate (unlike bipolar transistors) Should or shouldn't you have a 1M ohm from gate to ground? Let's say I'm driving a mosfet from a 555, should I have a resistor from the output pin to gate? I think the schematic I'm reading just through a mosfet in where a bipolar use to be without changing that resistor.

Topic by guyfrom7up  

Resistors are too warm

Hello,I am building a multi-touch surface using the FTIR method and after the surface is powered for about 10 minutes there is a heated smell in the room, I have noticed that the resistors are very warm and that a couple have started to brown or burn. I really need this table to be able to be safely powered at least 18 hours a day.Here are my specs:LED's:I am using 88 Infrared LED's (T 1 3/4 INFRARED LED, )--8 LED's per series--forward voltage of 1.5v --forward current of 100mAResistors:I am using 2, 10 ohm 1/4 watt resistors parallel (so 5 ohms) with each of the 11 series'Power Supply:The power supply output's 12 volts DC and 1.2 ampsWhen I calculate using it says I only need 1ohm 1/4 watt resistors, I haven't tried this yet but it doesn't seem to me that this would rectify the situation. My guess was that I need 1 watt resistors, but the calculator didn't seem to agree.Any thoughts as to what my problem is? is it safe to go with 1 ohm 1/4 watt resistors? or do I need 1 watt resistors? Any help would be very appreciated, thank you!

Topic by hapticdata    |  last reply

Resistors on each led? Answered

 I am designing a led array consisting of 17 leds in parallel using 4.5 volt power supply.The led calculator is telling me to use 62 ohm resistor on each - leg of the LEDscould I just use one 62 ohm resistor right after the power supply? Or maybe like 1 or 2 100 ohm resistors? I'm using blue leds 3.3 max voltage 20 Ma

Question by the_burrito_master    |  last reply

LED & Resistor help.. Answered

I was wondering if someone could help solve my problem as follows. I shall make as much detail as possible: I am running 12 (5mm led) in parallel of 3 in series. (So four rows of three leds) The Manufactors spec is Forward max Voltage = 4v Forward max current = 100mA Power Dissipation = 100mW This is all been run off 12V DC supply. So by my calculations (which may be wrong) it would require 1ohm, 1/4W resistors? However with all the above been used the last LED in each series of three has blown. Could anyone explain why or give advice please.

Question by goafer    |  last reply

What is the tolerance in resistors?

Topic name is pretty much self explanatory. What is tolerance in resistors?

Topic by Dantex    |  last reply

Resistor Voltage Drop

Is there any way to calculate the voltage drop of a resistor value? For example, if I had a 47 ohm resistor, would its voltage drop equal -30V, -857358V, or -0.5V?

Topic by puffyfluff    |  last reply

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.

Topic by Brennn10    |  last reply

What is a biasing resistor?

Can someone tell me what a biasing resistor is, and where I can het some? Thank you in advance.

Question by tesla man    |  last reply

Why are these resistors marked as such? Answered

Hi, I ordered a kit of assorted resistors (112 types, 10 of each), and it's awesome, however, some resistors are marked weirdly, like 1k8, 2k7, 1m8, 2m2, there's quite a few. What's the meaning of these?

Question by XOIIO    |  last reply

Resistors and LED question

Hello, I have a quick question about resistors and LEDs. If I am making an LED flashlight, do I attach the resistor to the (-) side or the (+) side? Thanks!

Topic by jknight    |  last reply

Powering oven resistor Answered

Hey :)Does anyone know how to power an oven resistor ? Is it really a simple resistor (I'm not sure as it is directly exposed in oven, it seems too dangerous for the user if it is simply a metal stick) ? If I plug it to 220V sine 50Hz will it heat ? Thanks :)

Question by QuentinP16    |  last reply

Why waste the resistors? Answered

So I see a lot of projects with like 60 LEDs of the same type or something like that, and they use a separate resistor for each LED. Why do they do this? Why not just get one resistor and hook it up to ground or VCC? Please explain, thanks!

Question by HavocRC    |  last reply

Resistors on the Bluetooth speaker!! Answered

I wanted to know why the resistors were used on the Bluetooth speaker and if I need them,  what size are they? 

Question by LASOUND    |  last reply

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.

Topic by Josho    |  last reply

"Shunt" diodes with resistors? Answered

I'm making diode bridges to have a nice supply of DC. I'm making a high voltage bridge for a 7.5kv nst and a low voltage bridge for regular 120v wall outlet . My high voltage bridge im going to make with several 1N4007 but i read that they should be "shunted" with 10Mohm resistors im not sure what is meant by this. Does it mean resistor, diode, resistor, diode or does it mean diode and resistor, diode and resistor. The pic says it better than i do.  Also, do i need resistors for a bridge for 120v bridge?, im going to use the diodes from a fluorescent light power supply.

Question by jaydenr    |  last reply

resistors for leds why?

I know i need resistors for leds, i know how to calculate what i need, etc. etc. but what im wondering about is why. why arent leds like glowing bulbs, what makes the difference in needing the resistor. also, why cant 1 resistor take care for multiple leds at the same time? please, if ur answering my questions, make it understandable english. im not comfortable enough in the world of science to understand that kinda stuff... (otherwise i wouldnt be asking these questions :D )

Question by godofal    |  last reply