The forums are retiring and are now closed for new topics and comments. The existing content will remain online and accessible through 2020 to provide everyone the opportunity to save any relevant information. In the spring of 2021, these Community forums will be taken offline.

Search for 3v in Topics

9v to 3v

Hey, I need to know how to turn 9v into 3v can anyone help? Thanks, Cory

Topic by Flumesoft    |  last reply

3v led strip?

I need to source a large quantity of light sources for interior emergency use. Needs to be a short, 300mm multi led light strip powered by a 3 v watch battery, with a mercury type position switch. Any ideas  where I could have them made?

Question by Algy    |  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

Build a 3v Relay Module

Would love a 3v relay module that can be drive by PIRs that output 3v signal.  Thought I finally found what I needed on Ebay, but discovered this is a bogus product that actually needs 5v to be driven. Buyer Beware. Advertised relay PCB as 3v relay. While the relay on the board may trigger independently with only 3 volts, the circuitry of the board demands a higher voltage to trigger the relay. Relay PCB has a EL817 opto-coupler for the input signal, it requires a 5V drive voltage on the Input in order to drive the onboard transistor which controls the relay coil current. With only a 3v drive, there is insufficient current to drive the opto and transistor. The module that the relay is mounted to is falsely advertised as 3.0V because the components on the board need more than 3 volts. In order to drive this relay with a 3v signal device, voltage level shifting needs to take place between 3v device and relay PCB.

Topic by DiyWaterDog    |  last reply

Potentiometre for 3v DC Motors? Answered

Hey Guys, Today I Need help selecting a potentionmeter for my 3v dc batteries, The setup will be like this, There will be 4 3v dc motors in parelllel drawing about 800 mah i think with a 6v 2 amp 4 aa cell battery pack. I want it to be so that when i turn the potentiometer to the lowest the motor goes to the slowest speed (or close) and when i do it the other way it goes to the highest speed (at 6v). Thanks in advance. -Prickly Potato

Question by SA-DIY    |  last reply

usb 5v to 3v fan

I'm considering running a 3v fan from a 5v usb. can i simply put adequate resistance in series to reduce current to acceptable levels?

Topic by Toga_Dan    |  last reply

How to change 3v to 2v?

I want to install some LED string lights in my garden. The package comes with a solar charger (2V 100mA), built in battery (600mAh) and 30 meters of wire and 300 LED bulbs. The problem is that I cannot use the solar charger this time of year. So I want to cut the wires and join them to a power supply. The lowest voltage adapter i can find is 3V. Do I need to change the 3V to 2V? How?

Question by MartinaA5    |  last reply

Arduino to control 3V remote

Hi,  I have a remote that I'm trying to drive with an arduino.  The remote usually uses a 3V CR2032 battery.  I tried just using the 5V digital pin set on high, but that didn't work.  Then I tried using a L293D motor driver -- with the lithium battery supplying the outside power.  That didn't work either. Any ideas?

Topic by gluckc    |  last reply

Strongest 3V LED with pins?

I'd like to build a LED into an empty light bulb that can run on 3V (from button cells). So I can't use the normal screw-in leds that are sold because they are all 12V at least. I'm planning to build the LED into the lightbulb myself, and connect it manually to the batteries. I'd like my LED to be as omnidirectional as possible. So what LED would I be able to use for this, and would I need some sort of diffuser or something to make the light shine in all directions? Would I be able to get up to about similar lumens as a 40W incandescent bulb?

Question by reinhardtsmit    |  last reply

Where is the 3.3V regulator on this board?

I need a 3.3V for one of my projects and decided to scavenge one from an old Arduino clone I had lying around. Only problem is I can't figure out where the 3.3V regulator is!! The board has a 3.3v pin and I've also measured a steady 3.3V output using a multimeter but all I can see on the board is a 78M05 and  a diode. I've uploaded a picture of an original Arduino Uno board I have for comparision. The 3.3v regulator on that one is pretty easy to find. Any help in finding the 3.3v regulator will be appreciated. Thanks.  

Question by newbie007    |  last reply

Is it safe to use the 3v ac adapter

Is it safe to use the 3v ac adapter to power up a small electronic equipment witch operating with 4.5 volts batteries or will damage the device

Question by NickS322    |  last reply

3v motor, 12v power supply

I have a 3v DC motor, a 12v power supply, and various resistors. Can I use resistors in series with the motor to keep it from burning up?

Topic by NOOBLMAO    |  last reply

Charge LiPo 3.7 240mAh with 3v?

I have been told that I need to use a charging controller to charge a LiPo 3.7 240mAh with 3v. I have searched and cannot find one. Any help? It needs to be very small as well. Thanks.

Question by Tuckoguy    |  last reply

Covert 12v dc to 15v and 3v?

Hi guys, I need to convert to 15vdc and 3vdc from a 12vdc source... any ideas? Efficiency isn't the biggest concern, but size and simplicity really come into play. i promise credit if it becomes an instructable.

Topic by gschoppe    |  last reply

9v to 3v "easy button" hack. Answered

Hello! Im working on a Staples Button Hack! but..... Problem that I have is that I feel like it is a Waste to scrap the original "that was easy" message. And the problem that comes along with this would be that I have to use a 9v battery to power the new circuit and the original button circuit uses a 3v battery. I'm not great with Ohms law but I do relize that I need a resistor but... i do not know if that will put in too much current into the original circuit?Would anyone know how I can calculate this? And does the amount of current even matter? -Thanks! Noobiefied

Question by noobiefied    |  last reply

3V Hobby Motor in a 6V Circuit.

Hi. Hope I'm posting appropriately. If not, please forgive an older guy! I'm working on a Useless Box project that I power from a 6V wall wart. I've already completed one and it works great. I use two standard servos with an Uno. But now, rather than being satisfied, I'd like to add a 3V hobby motor, which naturally would only run randomly for short periods of time. I have purchased an AMS1117 step down module which is rated at 800mA from Amazon to get the correct voltage for my little motor. My question is, do I need to add a capacitor across the leads or to the casing. If so, how do I determine what size? And while I'm asking, is there anything else I need to think about? I appreciate any help as this is a new hobby for me.

Topic by Steve_Lane63    |  last reply

9v to (5v-3v) for pic 16f628a

Problem: I have a 16f627/628 (runs between 3 and 5 volts) that needs to work in tandem with another device (call it D) running at 9, direct current, (active for 1 second in 30 or less frequent). Upon hooking up a number (of descending in size) resistors (without D connected) with the supply and 16f6xx the 6 LED's powered by the 16f6xx do not turn on unless resistance is extremely minimal, and voltage is well above that advised in the datasheet (not to mention making the pic reset itself every 10ms). Can anyone tell me how I might run the 16f6xx from a 9 volt battery, and explain what was going on? This may seem unforgivably dim to anyone who knows but unfortunately I'm more a software guy learning hardware as I go along. Any help would be much appreciated, Thanks Andy

Topic by andy    |  last reply

Can I hook a 3v solar panel up to charge a 3v lithium coin battery to keep a 3v chip led going?

The project is to light up the inside of a shadow box.   Currently I have a 3v 20ma chip led that is plugged into a 3v lithium coin battery ( CR2032) with a switch in between and that all works out fine.  My math figures that should get me maybe 5 days max of light for one chip led.  Which led me to thinking about a solar panel instead for the top of the frame for something that might last longer.  I'm looking at the PowerFilm MP3-25 Flexible Solar Panel 3V @ 25mA right now, but I think if I just do that, at best it only lights up with the lights are on and bright enough in the house if I use that in place of the battery. I'm kinda new to all this, and I'm trying to figure out is there a way I can hook the solar cell up to the coin battery holder to charge the lithium battery so it can use solar power or the battery or so it is always charging the battery?   My guess is that's a bad idea without something to cut off the charging once the battery is full.  Also, I don't know if that would fry the chip led because that would then be 6v coming through rather than 3.   I also think I read I would need something with slightly higher volts to charge a 3 volt battery. Also, to back track a little, the reason I'm using a coin battery rather than AAs or a 9v and a resistor is because I can fit the coin battery nice a flush with the back of the picture frame and it still hangs nicely, and leaves enough clearance for the power switch to stick out just enough that all you have to do is press the frame to the wall to turn it on and off.  Which gets us to if a solar charger could charge a coin battery, I'd still want to pull it off without extra circuitry on the back for the clearance reason (it's maybe 3/16" clearance at best).  Without adding a lot in parts, would it maybe be possible alternatively to make a flip switch so one position is using solar and the other is using battery?  If it was just adding the solar panel to the top and flip switch on the side, that would totally work.  I just can't find any info for something this small yet. Thanks for any info anybody has. ** EDIT Did some more research and I guess you can't recharge just any old C2032 battery.  But there are some that are rechargeable.  Amazon has these. So the question is still can I just hook a solar cell up to this battery terminal and have it basically just trickle charge?   Here's the coin battery holders I'm using. It looks like the way they come before they are wired up is they have a third prong coming out that they clipped off for this version.  At least from what I've seen sold on other sites that isn't per-wired.   No idea what that prong does or if that would be needed for charging. Also, I'm trying to follow this instructable but it seems to skim over a lot of things, or at least the details.  Sounds like maybe I need a rectifying diode and dpdt switch is what I'm looking for?   I'm trying to read up on the dpdt switch but I don't really fully understand what it does in this case.   The diode I get is for making sure the solar panel doesn't suck energy back out of the battery when dark.   Is this the right track? **** Edit Kept searching.  Are Super or Ultra Capacitors an option for something like this over the battery?  Just use that with a solar cell?

Question by technicallyartistic    |  last reply

Do I need to step down a 3.3V Power supply to work with a device that uses 2 AA batteries (3v) or is 3.3V close enough?

I need to power 14 analog cassette players with a single power supply, I have found a 3.3V power supply that has the amperage to power these devices but I am unsure if 3.3V will have an adverse effect on the speed (or lifespan) of the cassette players as they normal run from 2 AA batteries (3V)

Question by action_owl    |  last reply

3v leds x 20, leds paralel, 3v in, led calc says use 1 ohm each resistor, can I skip that since 3v led and 3v input v? Answered

I am building a led array light bulb. 3v leds x 20, leds parallel, 3v in, led calc says use 1 ohm each resistor, can I skip that since 3v led and 3v input v? Led calc also says 0 ohm / use the next standard resistor 1ohm.. does 1 ohm x 20 really needed for a 3.0- 3.2v white led with  a  3v 2000ma source> thanks in advance..

Question by celalboz    |  last reply

covert 3V battery source to 1.5 V

Hi Guys, I have a 3V battery source and want to convert it to 1,5V to run a device. How do I go about doing it? Will a voltage divider work accurately?

Topic by kurtselva  

how to replace 3v bulb of torch with LED?

How to replace 3v bulb of torch with LED?

Question by ajaysaini    |  last reply

attiny85 on two 3v coin cell batteries?

I've seen specs for attiny85 that say 6v, but most say 5.5v max, so I'm wondering if it's safe to use two 3v coin cell batteries to power them?  Such as CR2032 or CR2450.  I would only use one, but I need 4.5v for my LEDs.  Three AA is too bulky.  Thanks.

Topic by aliasjanedoe    |  last reply

How does a bug zapper work? Answered

To my understanding a capacitor can only be charged to the voltage it is supplied with. Well then how can a bug zapper circuit step up 3v (2 x AA batteries) to nearly 3000V. Wouldn't the capacitor only be charged to 3v? This may be a very simple question, and im sorry if it is, i would just like to learn!

Question by Jaxon0077    |  last reply

Rechargeable CR2 (3v) Battery Pack for a Digital Harinezumi camera?

I've been burning through CR2 batteries while using my Harinezumi camera. I would like to make a battery pack that wires into battery compartment, makes a connection with the terminals and keeps it juiced as long as the pack can juice it.   Ideally, I'd like to have the battery pack in my pocket with a wire going to the camera through a small hole drilled in the battery compartment door. I have about 10 rechargeable CR2 batteries with these specs... Rechargeable 3V CR2 800mAh which I've been using to power the camera just fine,,, just not long enough. How would I go about making a battery pack to give the correct current/power to the camera without causing any harm (frying it)?  Should I use and combine the batteries I already have , or should I make a battery pack with different, bigger, batteries? Once I figure this out, I'll post the complete instructable on here with photos of my project. Thanks!!!

Question by eldrizno    |  last reply

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    |  last reply

3.3V to 3V - Power a GameBoy Color from USB

I want to power my GameBoy Color using the USB port. It needs 3V ( 2 AA batteries). I found a voltage regulator, that puts out 3V, but it does not seem to be available in Germany. But there are loads of 3.3V regulators. So I wonder, how I could use one of those. Is it possible to simply put a resistor in row (if yes, what value would be suitable?) or is it a bit more complicated?

Topic by SpecieS~    |  last reply

Is is possible to build a mini generator for my 3V adapter?

I have a 3v adapter I use for small electronics when I don't want to drain the batteries. Is it possible to build a mini generator to plug the adapter into when I'm on the road? So I don't have to use up so many batteries? Some kind of super battery I guess.

Question by buffysissy1    |  last reply

How to change 5v into 3v using only resistors?

I need to change 5 volts into 3v, using only resistors, to power a LED, I can't use a voltage regulator, because the LED is to see if the current voltage regulator is working, I am happy to reply to questions that would help you answer it. Thanks

Question by alexw2150    |  last reply

How can convert a 12v power supply to 3v?

I am working on a laser spirograph project, I am using 12v dc fans on the inside but also want to power a 3v laser diode off the same source. Does anyone know how I can allow the full 12v to be used on the fans but drop down the voltage for the laser?

Question by ugman77    |  last reply

Making A Dual USB 3V TO 5V Converter, HELP?

So I was browsing the web and came across this "3V to 5V 1A DC-DC Converter Step Up Boost Module 1PC" and was curious to know if i could attach a "Dual Usb Type A Female PCB Connector Component" to it?  Is this possible,  because I know that the single "Step Up DC DC Converter Boost Module 3V To 5V 1A USB Charger" has one output connector. Therefore if i buy the module without the "USB PCB connector"  will it be able to support a "Dual Usb PCB connector" once I soldered it on?? 3V TO 5V STEP UP MODULE LINK: DUAL USB FEMALE PCB CONNECTOR LINK: Please let me know if this will be applicable in response! thanks for your time ,RookieSean

Question by RookieSean    |  last reply

3v Relay Module and PIR sensor circuit troubleshoot

​Looking for help on my project.  See image.  Testing before connecting to high voltage device.  Using a 3v relay triiggered by the PIR signal.  As you see wired now, There is no ground wire coming from PIR.  The circuit would not trigger relay with a ground wire to the PIR.  When this does trigger I noticed on the relay that the LED would not go completely off.  So I check to find that when relay turns "off"  the PIR is still sending 2.8 volts to the relay.  Not enough to trigger the relay, but enough to show power through the LED.  Obviously something wrong here where the PIR or Relay are still drawing power.  Can you help?

Topic by DiyWaterDog    |  last reply

How can I power a 12v LED strip with a 3v coin battery?

I am working on project with a flashing led strip, 6 bulbs in total. The circuit includes a 555 timer.  At first I was using a 9v battery but then realised that battery is way to big. A coin battery (CR2032) would be perfect. How can I power the LED strip using the 3v coin better? I am pretty new to circuitry so any help would be greatly appreciated. Thanks in advance. 

Question by JFrankly    |  last reply

what should a hotel General Manager do with all the forgotten Cell phone chargers

I'm a General Manager at a hotel and have worked at a number of different hotels through the years. Every place I've ever worked there is always a huge bin of long lost cell phone chargers. We've looked at donating them to charities but haven't found anyone in need or a use for them. I've used some in the past for projects. Is there any other uses for these or a place that people could use them. As a service to our guests we always keep a few around for the guests that forgot theirs at home but we always have more then we would ever use for that purpose.

Topic by dag4415    |  last reply

fast and easy way to get 3.3v from 5v without a lm317? Answered

I got a dvd player but the power supply was missing. i can get the 5v and the 12v, but other than a lm317 (which i dont have) i cant get 3.3v. ive looked at all sorts of things to try and find a 3.3v regulator, but everything i have searched up lead to several misleading results. so i was wondering, what value resistor could i use to get 3.3v from 5v or what devices could i look in to find a 3.3v regulator? i have several computer motherboards, a bunch of cd drives, a couple hard drives, etc. please help! thanks in advance,           zack247.

Question by zack247    |  last reply

how much time will it last ,a throwie of 10mm with a battery of 3v?

How many hours or days will the led be "ON"? using a 10mm led with a 3v battery

Question    |  last reply

What is the simplest and most efficent way to convert 3v to 5v?

There are several circuits out there on how to up-vert a 3v input to a 5v input, hwever I would like to know the simplest way.

Question by Sargebubbles26    |  last reply

How do I use PIR motion sensor to trigger 3v relay module? Answered

​Looking for help on my project.  See image.  Testing before connecting to high voltage device.  This is my first attempt using a relay. Using a 3v relay triiggered by the PIR signal.  As you see wired now, There is no ground wire coming from PIR only Red + and Yellow signal to relay..  The circuit would not trigger relay with a ground wire to the PIR.  When this does trigger ( without the ground wire on PIR) I noticed on the relay that the LED would not go completely off.  It dimmed showiing that the relay board was still receiving power. So I check to find that when relay turns/switches "off"  the PIR is still sending 2.6-2.8 volts to the relay.  Not enough to trigger the relay, but enough to show power through the LED.  Obviously something wrong here where the PIR or Relay are still drawing power.  Can you help?

Question by DiyWaterDog    |  last reply

6v dc./sla. down to 3v dc to power a 1w.Duracell led flashlight that normally runs on 2 aa batteries or 12v to 3v.

This set up is for a bike light, I have access to a 6v sla. batt. that came from a larger flood light that was useless because of the power sucking halogen bulb,approx 15 min. run also has its own charging circuit and a separate circuit for a single led night light.I tried looking up resistor values,but get confused cause i'm getting different answers from different sites ! LOOSING MY MIND ! HELP ! thanks oh..I use the night light circuit to power a red led flashing bike light for the rear.

Question by robin67    |  last reply

How can I make a 3.3v Solar power supply that uses an 18650 battery?

I have a project which I would like to make self sustaining solar powered that runs 24hrs a day. the electronics themselves use between 60ma and 220ma of power. the 220ma is for about 1 second every 2 minutes when the device transmits it's sensor's data, the rest of the time it is 60ma to 80ma. I want to make sure that the circuit has overcharge and over discharge protection for the battery as well as voltage regulation to between 3v and 3.3v for the load. I have been searching and I cannot seem to find a premade solar controller board that will do what I need. If there is one <$20 USD please point me in that direction, but I would still like to learn how to build one.

Question by funinalaska    |  last reply

Control a 12v LED strip with a 1v to 3v supply. in an 8 LED chaser project 12v strip has to mimic the same as 3v Leds.?

I have an 8 LED chaser project with a PIC 16F682a at the heart of the project. The Pic is programmed to display programmed patterns and each Led has 4 brightness levels.I found the Led's to restrictive and wanted to use 48cm strip Led lights which require a 12v supply. As the maximum current that the PIC can source from an I/O port pin is 25mA and was intended to drive up to 3v Leds with a 270 ohm limiting resistor. I simply want to replace the 3v Led's with 48cm 12v strip Led's for a larger display. 10 years ago I could have knocked up this circuit in a few minutes but I have trouble remembering anything these days. Any help would be very very much appreciated and hopefully the folk of the indestructibles might find the information very positive when applying this in the future when larger Led arrays are needed. The project would also make a cool disco lighting effect too as it comes with 34 pre programmed effects. PS: I would like to add a 5 bit PWM signal providing each of the 8 LED channels with four levels of intensity; off, dim, mid, bright. I have looked in a logic level shift but feel very out of touch being away from electronics in pursue of another career. Thanks again Spence See here for original project.

Question by CodfishCatfish    |  last reply

can you u get 12 volts down to 3 volts by using a 5 volt regulator and a 1/4th wat resistor? Answered

I need my car to go from 12 volts to 3 volts for LEDs... please help me!

Question by led235    |  last reply

continuity between 3.33v and gnd on atx psu?

Im converting my atx into a bench psu. I was checking the continuity between 5v and gnd that i connected to the LTC3780 and i got a beep (one short beep). So i checked the rest of the lines and 5v and 12v also 1 short beep. However on the 3.3v. i get  a long continuous beep. Is this behaviour to be expected?  thank you in advance.

Question by icey.hood    |  last reply

Stepper motor driver?

Hi! I am trying to find a good h-bridge for a 3 volt stepper motor. Basically my plan is to build a stepper motor controller with an arduino for controlling various functions in a model kit. I have the arduino-kit and the motors. But I need a good reference for a h-bridge, but all i can find are chips rated for much larger drive currents. Also exactly how hot does a hbridge get when under load? I would like to integrate the bridges into the kit, but since it is plastic, I would like to know in advance how hot it gets, and if it gets too hot I'll have to look at another solution.Any help appreciated! PS. If you can please put the hbridge part ID in your answer for easy reference. DS.

Question by feldreich    |  last reply

power supply voltage reduction 9v input to two 3v outputs

Hello all ! I'm new to instructables and I’ve found some cool and helpful information for my projects. I need a bit of help designing a power supply voltage reduction device. One that accepts 9v input and output into two 3v 5mA outputs. I want to replace the batteries in a/b Boss selector with a more reliable source of power.

Topic by testpartner    |  last reply

which has high rpm and torque, the 3v dc brushed motor or the 12v brushed motor, they are running the same at 6v battery

Is it advisable to use a 12v motor to have high torque and rpm than a 3v motor?they both run at 6v,

Question by LDN Machines    |  last reply