Ohm's law?

So, i have a broken soldering iron, and i want to fix itcan someone =smart= calculate the required resistance of wire at 120v aci don't care about the amperage, as long as its under 2 ampsplease give me a range of resistance, i don't like to trip fuses, (my parents hate that!)

Posted by Sandisk1duo 10 years ago


Hi all,  I got two 3-way-speakers (8ohm) from my uncle, but I don't have an amplifier. I wanted to use these speakers as audio-monitors for my pc. Is it possible to make an (easy) amplifier-circuit for this use? And do I need one or two circuits (1 circuit-1 speaker / 1 circuit-2 speakers)? Thanks for helping me out! Arnout PS: Sorry if my english isn't that good - I'm from Belgium ;)

Posted by arnoutdejans 6 years ago

I need help correcting impediance on speakers.

Here's some background on what I'm dealing with: I run a haunted house in Nashville TN called Devil's Dungeon. We have a sound system that is controlled from a rack with 6 2 channel power amps. 4 of them are 260W by 2 channel and 2 are 500W by 2 channel. I have 10 cd players running to a 24 channel mixing console and the way I control each room on a separate channel is by using the post-fader sends (yeah, it's a really old peavey, but the new ones don't have post -fader sends per channel) as a line out per channel. IE: i run a line directly from the post-fader send per channel to the power amp's input. Here's my problem: There are more speakers than there are outputs, and the speakers are placed where they are needed in a particular scene. It is a large building and it would be highly laborious to try and correct the impedance by putting extra speakers and with series/parallel combinations and as we are already open this season and I don't want to re-engineer the entire system. Is there any way to correct the impedance with some kind of variable resistor? Everything I've seen so far that could handle the power is pretty large, and if possible, I'd like to put it in a relatively small project box. Can this be done with a potentiometer? I only need to correct it by a few ohms and the only POT's I've seen have been in K increments .

Posted by Scurge 10 years ago

Laser ohm resistor project question

So I am doing a big modifiction of Kipkay's burning laser project. I am making it into a gun, and the only resistor I can find is a 4.7. Will that do? I have a 5mw module like his, and a 250mw 650nm laser diode. Also I am going to use two C-batteries, so its 12volts total. 

Posted by thedonquixotic 8 years ago

Component Amperage Rating

Hi! I was browsing through an electronics retailer website looking for components to buy (particularly a LED) and i was wondering what the amperage rating of each component meant Does it mean: 1. the current flow across this component shouldn't be more than the amperage rating as it will cause damage? 2. or the current flow across this component should be equal to this amperage rating? please help me I'm really confused :(

Posted by La Tour Rouge 9 years ago

Need help understanding LED drivers

Ok, I'm a newb to electronics and i'm having trouble figuring something out. Inspired by Dan's instructable, I decided to try and build my own headlamp. However, I've run into a problem. I have no idea what LED driver to use. I'm planning on using three of these bulbs, at 3.7v each and a max wattage of 4. I know if I rig them in series, the LED driver needs to be at least 11.1V, but my question is does the wattage of the driver need to be 12? Or should I rig the bulbs in parallel from my power source, and have one of each of these rigged to them individiually? Also, advice on whether it would be preferable to rig them in series or parallel would be great. Any help would be greatly appreciated. Thanks in advance

Posted by The Insomniac 6 years ago

Ohm's Law watch...

Has anyone seen this?  "Ohm's Law Watch" For those of us that have difficulties with formulae, this looks like it might be handy :-)

Posted by Goodhart 7 years ago

building a complex amp simple cheap

I need to build a complex amp for cheap and as simple as possible i need it to -run speakers at differant ohms safely -have left and right channels -have little distortion -have 3 inputs -have outputs that can run at least 6 speakers off of each channel -have volume control -off/'on switch -portable and have to run of of 9V batteries (as many as it takes) so how can this task be compleated

Posted by fastcar123 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

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

Unabel to find any Audio Transformers (the little cheap ones) 500 ohm to 8 ohm

The only one's listed on eBay are high end (fairly to extravagantly high priced) transformers. I just need a little 4 legged 500 ohm to 8 ohm audio transformer. All my catalogs seem to offer little help. No need for the C/T like the one pictured....

Posted by Goodhart 9 years ago


I need to create a Dummy load of 50 amps at 18.5 volts DC so I will need to dissipate 1000 watts, was thinking of using 10 x 100 watt 100 ohm resistors from EBAY will that work, there are others at 4 Ohm etc, what ohm should I use?

Posted by TrevorP55 1 year ago

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?

Posted by craig3 10 years ago

symbols appearing as boxes

Hello , when i post the symbol for ohms (Ω) it brings up a box as you can see, i dont suppose there is anyway around this

Posted by Cew27 9 years ago

how many ohms does this resistor have in the led


Posted by dereklevine158 5 years ago

solar cell amperes

Lets say I have a solar panel that gives off 5 volts at 30mA. if I were to put a ten ohm resistor in series with it would There be basically no effect because a 10ohm resistor woulkd limit it to half an amp, which is way more. Or does the solar panel act like ~ 167 ohm resistor, and adding a ten ohm resistor will limit it to 28mA?

Posted by guyfrom7up 10 years ago

LED burnout

I've have an LED problem that I have done extensive reading and troubleshooting on but I can't seem to solve it. I'm running 4 super bright white LEDs (NTE30071) in parallel from a 24v 600mA DC wall wart. The LEDs are 4V, 25mA. I need that wall wart to also run a solenoid. When a button is pressed a relay powers the lights and the solenoid for a few seconds. The problem is my LEDs keep dying. At first I had a 10K ohms 1/4W resistor on each and I lost 3 LEDs. After more study and calculation just replaced them with 1K ohms 1/2W resistors. After a few more hours I lost another. When I removed the 10K ohms resistors they read 1K ohms. And I just tested the one on the 1K ohms resistor that went out and it reads 200 ohms. I know there is something that I just don't get; something basic that highlights my lack of any electronics experience. I appreciate any help you can give, this is just is just wearing me down.

Posted by robotninjasquid 11 years ago

Instructables Request: How to a make a balun transformer for a TV antenna

Greetings, I am looking for instructions on how to make a balun transformer for a TV antenna. 300 ohm antenna to 75 ohm coaxial cable jack. Thanks

Posted by NeuroPulse 8 years ago


After reading this, and then this, I started thinking of how easy it would be to make a burning laser. I went to Radioshack, got some components, and started thinking. One thing that Stephanie's laser didn't have is a potentiometer, to control the power of the laser. Well, I ended up getting 12 assorted pots at Radioshack, but didn't know what one to use. I want decent control, too. What size (in ohms or k-ohms) do you think I need? I'm spotty in my electronics knowledge. PS- The size in ohms on the pot is the pot's range, right? If it says 100k, it means that it will resist from 0 to 100 kilo ohms, right?Also, in the shematic below, I don't know if the pot is connected correctly, post a comment if it's wrong.

Posted by John Smith 11 years ago

Speaker and Amplifier Wiring Please Help!

As you can see I have a car amp and some speakers, can anyone with speaker or amp knowledge please tell me (or even better draw a diagram :D) of the best (most efficient / loudest) way to wire all these up, the specs are as follows… AMP 2/1 channel amplifier Max power – 400 watt 4 ohm stereo – 2 x 75 watts RMS 2 ohm stereo – 2 x 100 watts RMS ROUND SPEAKERS (midwoofers) 4 ohm 25 watt RECTANGE SPEAKERS (tweeters) 4 ohm 4 watt Thanks for your help! (P.S my plan is to build a portable sound system powered by a car battery)

Posted by superrob 6 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 9 years ago

battery life

Any one know about how long 4 double a's wired in series will last with a 200 milliamp load, here is what the online LED calculator said, I'm working on putting this in a small flashlight:Solution 0: 1 x 2 array uses 2 LEDs exactly +----|>|---/\/\/----+ R = 27 ohms +----|>|---/\/\/----+ R = 27 ohmsThe wizard says: In solution 0: each 27 ohm resistor dissipates 270 mW the wizard says the color code for 27 is red violet black the wizard thinks ½W resistors are needed for your application together, all resistors dissipate 540 mW together, the diodes dissipate 700 mW total power dissipated by the array is 1240 mW the array draws current of 200 mA from the source.-thanks

Posted by firemanfu 10 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 11 years ago

reducing current on a power supply

So I am trying to reduce the on the current power supply I have from an old router. The out put is 12v DC 800mA (.8A). I want to use it to run a man 12v .3AI just wanted to make sure I did my math right and to make sure I didnt miss anything.Ohms LawI = V/RR= V/I V = 12 I = .812/.8 = 15 ohms resistance in theroy_Current on the fan is .3 A, I am assuming that is the max. So desired current is .25I = .25 V = 12 R is current resistance, X is additional resistance Q=(R+X)I = V/QQ= V/IR+X = V/IX = (V/I) - R V = 12 I = .25 R = 15(12/.25) - 15 = 33 ohm resistance neededSo I would need a minimum of 33 ohm resistor. Am I correct?Sorry for the explicitness of the math, its been drilled into me to show every step.

Posted by dragonkeeper117 9 years ago

can someone explain this for me?

In the picture of the schematic there is + symbols and i dont know where to connect them, specifically the 10M ohm one, can you lend a hand?

Posted by Yerboogieman 10 years ago

Troubling Flyback Transformer Pins

Hello,       I'd like to request someone to share their knowledge about their "flyback" knowledge or experiences with me since I'm having trouble finding the primary coil pins with my flyback transformer. I'm constructing my own HV power supply and I decided to go through this tutorial.       I've read much on the web and found the 0v output pin of my flyback. The problem is .. I couldn't find the primary and secondary since I'm using an analog multimeter and the tutorials on the web are all digital..       When I test the pins with my multimeter set to ohm range of x1, I do not get a pair of 1 ohm pins but instead I got the result of "Continuity" when I test on following pins, they seems to be connected but none of the pins show to 1 ohm.. and thus I've adjust the Ohm Adjustment. The results are Continuity 1 : 1,2,6,8 Continuity 2 : 3,4,7,10 No Continuity: 5,9 Pin no 5 is 0v output..  I've attached the pin number diagram at photos... my drawing and actual pins.. Have you got any idea to find out the primary coil? I've also attach my driver from CFL.. Thanks

Posted by 3 years ago

Beginner In electronics

Hey, I've just started getting into electronics, it interests me alot. I have a pretty good understanding of each individual component, but don't have a good one of how they work together, so do any of you know of a good 'circuit cookbook' that has easy circuits with explanations? That would be great. Also, what components should I always have around if I'm just tinkering? I have a bunch of resistors (1 ohm to 1M ohm) and a bunch of capacitors (.22 UF to 2200 UF).

Posted by Jackhole 10 years ago

What is this electronic component?

During one of my part harvests I came across a rather odd component. It looked like a black rectangle with steel pegs protruding from one of its sides. The part's etchings are a white dotted line followed by what appears to be a mitsubishi symbol followed by the text "E 27k", an ohm symbol, then " 9428". I found this part on the board of what I believe to have been part of a tape recording machine. Attached is a picture of the component. If anyone can identify the part I would be eternally grateful.

Posted by fdsafdsaqwrewqrbsafdsagrgew 6 years ago

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?

Posted by puffyfluff 10 years ago

making a IR Light

Im planning to build a IR light using 10 IR leds in parallel with a forward voltage of 1.2 and a forward current of 100mA and five 6.8 Ohms resistors. Will 2 AA batteries be enough for this Thanks

Posted by specializedrider 9 years ago


Potentiometer ARCING inside :( Anybody know what's going on  ? I'm using a 100k to control a 50k ohm load . i smell lots of smoke . It's a LM386 with pots at the output section to a 8W power amp .

Posted by Thereyouhaveit 7 years ago

Which cell & how many do I need??

I'm new to this whole electrical engineering thing. Thx to instructables, I got a crash course in LEDs & wiring them up. I need to make a prototype LED array. How do I determine the right size & qty of cells (9v, AA, etc.) needed to run an array for a decent amount of time for an end consumer? What's the equation for figuring this out? Will the Ohm's Law equation (which I'm new to) work for me here? Anyone's help would be greatly appreciated!

Posted by firesurfer 9 years ago

Bench power supply build from ATX power supply acceptable voltage

Hi, I built a bench  power supply from an ATX power supply and I am not sure if the voltage is correct. I am getting 5.74 volts off of the 5 volt supply and 12.7 volts from the 12 volt supply. Is that too high to use or should I try to bring it down a little? When I built the supply I didn't have a 10 ohm power resistor so I used a 6 ohm 10 watt resistor. Could this be the reason for the higher voltage? Thanks for any help you can give me. Dan

Posted by danridge 7 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 - http://www.theledart.com/blog/archives/category/kits Please view my Instructable for the detailed information on Aurora mini 18. Contact me if you have any questions. <br>

Posted by ledartist 7 years 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

Zener Set Voltage Signal Circuit (help)

Hey Everyone- I have been researching on ways to send out an electric signal to trip a relay to shut off my battery charger. I did find some simple circuits and I did the math for what I would need and could not find big enough zener diodes and resistors. Battery+(Resistor)(Zener Diode)(Relay Input)(Battery-) I need this circuit to send a 8.2 or 10Volt 15mA signal to my Relay when the batteries reach 235 volts. Following are the SPECS for the Input signal on my Relay::: Control Voltage Range 3-32 Vdc 90-280 Vrms (60Hz) 18-36 Vrms/Vdc Max. Reverse Voltage -32 Vdc - - - - - - Max. Turn-On Voltage 3.0 Vdc 90 Vrms 18 Vrms/Vdc Min. Turn-Off Voltage 1.0 Vdc 10 Vrms 4.0 Vrms/Vdc Nominal Input Impedance 1500 Ohms 60K Ohms 9.0K Ohms Typical Input Current 3.4mA @ 5 Vdc, 20mA @ 28Vdc 2mA @ 120 Vrms, 4mA @ 240 Vrms 3mA @ 24 V Any help on this would be great Thanks!

Posted by rc_rs_ss 7 years ago

Voltage boost

I'm trying to make a remote shutter release for my large format lenses. I found a solenoid that will do the trick. It's 12v / 36 ohm push solenoid with 3/8" travel. I prefer to drive this thing with a single AA battery. Is there a simple way to boost 1.5v?

Posted by JonLoder 5 years ago


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

Posted by Yerboogieman 11 years ago


This laser says: 240mw pulsed, 100mW CW 5.6mm red laser diode does that mean that it's 240mW or 100mW? Should I install it in a 5.6mm laser module? if I were to hook it up to AAA should i just put a 1/4watt, 1.8 ohm resistor in series?

Posted by guyfrom7up 11 years ago

5.5v DC supply on a 12v LED ?

Hi thanks for reading. I'm building (from the ground up) a set of 3x6" > Amplified 3 watt stereo Planar full-range speakers to be powered from a Cell Phone. I have most of the required parts which are many. One of the parts of the system I'm installing is a Blue LED (Amp On) Indicator. I'm running the system from a USB Charger or a Cell Phone USB Port at 5.5 volts. I went forward and ordered the Blue LED's and they haven't arrived yet so I can't test. These LED's are from E bay with little info of course. They are said to be standard, Blue 2mm 12 volt LED's. (Not Ultrabright)  ------------------------------------------------------------------------------------------------------- My question to you who may know: Are (Rated) 12 volt LED's likely to light from a 5.5 volt power supply? I guess my confusion is between the 12v claim and the LED Color Standards for a Blue LED.. ------------------------------------------------------------------------------------------------------- Without knowing the complete situation, here is the resistor value I've been able to come up with based on *LED Color Standards (Blue) and Supplied Power (5.5v): (*Blue) LED calculator: Current limiting resistor value: Source voltage = 5.5v LED voltage drop = *3.5 LED forward current = *20mA (=) Current-limiting resistor needs to drop 2 Volts. The resistor value is 100 Ohms, the next higher standard value resistor is 120 Ohm. The resistor will have to dissipate 0.04 Watts, the resistor should be rated 0.067 Watts, a 1/8 Watt resistor should do it. Final: 120 Ohm, 1/8 Watt. (color code: brown red brown, Silver). (100 Ohm: Brown, Black, Brown, Gold). ------------------------------------------------------------------------------------------------------- Thanks for the help! I hope I made some sense here ;)

Posted by Rexrich 3 years ago

basic electronics question - series circuit

Hi i have a device which normally uses a transformer rated at 2 amps outputting 5 volts.  i want to put together a battery pack to power this device.  it's easy enough to put together the batteries and get a 6 volt output, but i'm worried about burning out the device w/a 6-volt power source.  i'm thinking putting a resistor in the circuit should be enough to lower the voltage to 5.  if i remember my high school physics right, i'd need a resistor whose resistance is r = (v1 - v0) / i = (6 - 5) / 2 = 1/2 ohm ...but this seems strange.  1/2 ohm??  my approach must be too naïve.  can anybody point me in the right direction? thanks doug

Posted by dielan123 7 years ago

Voltage from 4 wire bipolar stepper motor!

I've stripped a 1.8 deg stepper motor out of an old fax to make a bike generator but I can't get any juice from it. I'm spinning it using a multi tool so I should get something, right?! I did do some research and found out that 4-wire bipolar stepper motors are controlled differently from 5+ wire ones. I guessing then that generating power is different also. I'm reading 2.1 - 2.3 ohms off each coil. Tried wiring the coils in series but still nothing. I need a long serving instructablator to help me!! The label reads: STP-42D1020 1.8deg/STEP 2.1 ohms 33.5 V D.C. 0.7 A 17845G SHINANO KENSHI CO LTD. CHINA

Posted by ZdEEvO 9 years ago

How to Lit a 1watt LED using a NOKIA charger

I would like to lit 1w Power LED using NOKIA Charger. Mostly, a 1watt Power LED's specification is 3v0~3v4 DC Volts and 350mA Current. Printed specification on Charger Cabinet it is for - Input 100/240v 50~60 Hz…„ Output 5.7v/800mA. For Series Resistor's Value…„ if we calculate upon Ohm's Law - for VoltageSupply, Vs 5.7v…„ ForwardVoltage, Vf 3.3v…„ ForwardCurrent, If 330mA to lit single LED. In Result we can use a Standard Value of Resistor 7.5 Ohm and because of Resistor's Power Dissipation 792 Milliwatts, can use a 1watt. In series I planted 10 Ohm 1w Resistor instead of 7.5Ω. LED lit up in normal. Neither too much nor too little shining. But…„ about two and a half hours later it was flashing. I switched it's off and checked that the charger unit also became hot. Where I made mistake…? Please HELP how to lit this 1watt LED using this NOKIA charger. I also have one another charger with printed specification on cabinet it is for - Input 100~240v 50/60Hz…„ Output 5.2v/400mA. I also want to use this for one another 1watt Power LED to lit. Please help for this too. please ignore my  bad english.

Posted by free2atc 1 year ago

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, http://www.allelectronics.com/make-a-store/category/340250/LEDs/Infrared/1.html )--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 http://led.linear1.org/led.wiz 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!

Posted by hapticdata 10 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

Coilgun, Marx Generator or Voltage Multiplier

I am building a coilgun and I have constructed a coil with several thousand turns, an ohm meter measures its resistance at 300 ohms, so I am having trouble powering it, I ran 240v through it and got nothing. According to my calculations, I need to run 1000 volts at the minimum through the coil in order for it to work. From my research there are three ways to do that: 1)A really big transformer (sub optimal for many reasons) 2)A Marx Generator 3)or with a Voltage Multiplier. Now I realize that you are supposed to connect the voltage multiplier to the Marx Generator, but wouldn't it be easier to just to make more multiplier stages and remove the Marx Generator entirely? I've seen voltage multipliers go up to 15kv, which is more than enough.

Posted by geekman2 4 years ago

My birthday wishlist

(*Hopes new topic draws people in...*)In lieu of this (is this correct usage?), I was hoping I could also be helped. I'd also like a hovercar... but I think you need a licence...Hmm -- I'm thinking electronic components -- but thats hard for them to get... (They'd get me 1,000 1 Ohm resistors >_>_

Posted by zachninme 11 years ago


Looking for some help with an audio issue in a museum kiosk. I have a small 10 watt stereo amplifier running a single 8 ohm speaker. My audio source file is in mono and need to keep the single speaker. Using shielded stereo audio cables. There is a faint amount of static coming from the speaker. Is there a way to reduce this noise/static?

Posted by jimboothdesigns 4 years ago

Identify resistors? - well, sort of

So, i have a bunch of project that i want to do, i have schematics and the parts (but i don't know what the color bands of the needed resistors are) Can some one give me a link to a utility converting numbers (470 Ohm) into color bands (yellow, violet, brown) please help/reply! thank you!

Posted by Sandisk1duo 10 years ago

Stepper Motors..

I recently pulled two stepper motors out of a working IBM dot-matrix printer. One larger, 3v one with 1.8 steps. The other is a smaller, 9.5v one with 7.8 steps. I am more interested in the large one right now. I managed to find out that the large one has center-tapped coils. I also found out that Coil 1 is red-white-brown, coil 2 is blue-black-yellow. I found the schematic below on http://ashishrd.blogspot.com/2007/09/computer-controlled-stepper-motor.htmlI was wondering how this could be adapted to control my motor from a PC program with the ULN2003 (that chip sounds like UT2003)? Here are the complete residences of what I found on the wires with a multimeter, in case that helps. Resistances:Red to Brown: 8 ohms (or 7 some times)Red to White: 4 ohmsWhite to Brown: 4Blue to Yellow: 7Yellow to Black: 4Black to Blue: 4

Posted by l0cke 11 years ago