LED Voltage indicator

I have recently installed a solar panel in my garden to charge a 12volt 21Ah battery. I would like to show it off a bit by using a simple LED display to show it working. What I was thinking was to have a range of about 8V-25V. At the low end would be blue leds (for cold) up to red (hot) at the high end. Does anybody have any idea how I would go about getting something together. I can read circuit diagrams at a push (my Dad's the expert) and would like as much information as possible. Would it be possible to have 1 LED per volt ? Am I being simple? Would this project be self defeating in that it'd use lots of the free power I'm trying to collect? Any help anybody can give I'd be grateful to receive. Share & Enjoy. Zippy.

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


Low battery indicator

Can someone please provide me with a schematic to turn on an LED when a 9v PP3 gets low (~<20%), no microcontrollers, the simpler the better. I am hoping you can do this with a few diodes, transistors, resistors, and maybe some capacitors, but I can't think how this would work.

Topic by andy70707 8 years ago  |  last reply 8 years ago


Problem with low battery indicator

Hi guys, I have built a low battery indicator circuit for a 6V battery source. It will light up a led when the voltage reaches below 5V. The 6V battery source powers a servo motor, which is controlled by a microcontroller. The problem I have is that when the servo motor rotates, the led lights up. And when the servo stops rotating, the led goes off. This happens even when the battery is above 5V. Any idea what is wrong? And how I could rectify the problem? I have attached the circuit of the low battery indicator, if it helps.

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


Low Voltage Disconnect?

Hi, I would just like to seek your assistance and idea for the observation below on my experiment: I have a gadget that is being charge by a 2w 9v solar panel, the problem is I haven't place a blocking diode and I observed that when I tested the charging slot there is about 0.16v output. To clear it that was supposed to be my input voltage. 1. Question is why does it produce an output voltage even though it is imy input voltage? 2. Would the 0.16volts output have a significant effect on my system during night time and or bad weather? Please give facts and computation if possible. 3. If I want to step down my input voltage of 9volts to 4.5 volts can you give me the idea how to do it. Well, I am asking you this because your insights and helps for me in the past are very helpful for my science project. Thank you teachers

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


Low voltage AC?

How can I make a simple circuit that will produce alternating current using 1.5 to 9v power supply? This is an experiment for using an AC voltmeter - that is, making the needle move.

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


Low voltage cutout

Hello, I need a simple circuit to switch off a high brightness LED that draws 200ma when my four cell Ni-MH battery pack drops to 4.0v(1.0v per cell) Nothing too complicated, something with a transistor, a comparator circuit, and a zener or an all in one IC? I've tried a few "this should work" circuits and then have been told, "well I haven't actually built one". Thanks.

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


Help fitting a low voltage indicator into this circuit?

Hello,I know very little about circuits and electrical components, so please be kind.Attached is a picture of a simple circuit. "A" is a 4,5V AAA alkaline pack, "B" is a latching pushbutton switch and "C" is a nicrome wire.In the simplest and cheapest way possible, this circuit needs to alert the user if the battery pack goes below 3V. The indication signal needs to be a "beep", just like a 9V fire detector. (I can't have a LED signal).After some googling, I found that a 3V "low signal relay" could be one option. I prefer to use wires, and not a PCB in my circuit. My questions follow below:1. Is a low signal relay this the cheapest and simplest way, or are there others?2. What components do I need to achive the "beep" and where in the circuit do these components go?3. Will these components draw any power in standby mode, or do they only consume some power when the "beep" goes off? Because if they draw power continuously, I will need to add an extra (coin cell?) battery, as I need to save my alkaline pack for the nichrome wire. The extra battery shoud last for min 3 years.All help highly appreciated.Thanks!/Karolina

Question by karolina81 5 weeks ago  |  last reply 5 weeks ago


Charge level indicator?

I need a nice, simple charge indicator. I have a battery pack that holds 4 AA NiMH batteries. Normally they charge up to 1.3V per cell or 4X1.3=5.2V total. I have a solar trickle charger on there too and I'd like to have a little charge indicator.   Requirements are: -low part count -under $10 -small (it's on my bike helmet) I was thinking something with a pushbutton an LED or two and a zener diode. Something that turns on the LED at  greater than 5.2 volts. But I don't have experience with zener diodes. Has anyone seen a system like this around? Can you think one up? -Cheers

Question by snotty 8 years ago  |  last reply 2 years ago


RGB LED Voltage indicator for 15 - 10 volts

I would like to make a one RGB LED DC voltage indicator, 15 – 10 volts in half volt changes.  At first I thought I would use a bunch of zener diodes, but it seems a bit more complicated than that as on my chart how I want the colors indicated.  Any ideas how I can accomplish the circuit?  There are probably new fancy things I could use but am not aware of since it’s been a very long time since I’ve made a circuit.  I am currently just using an analog panel meter.  It would be nice have a colored light indicator.  If it could be done.

Topic by K00kie 4 years ago  |  last reply 4 years ago


indicator lights to show voltage.?

I live in the jungle in Thailand, in the morning the electric supply is only 145 volts till 8 am at that voltage many things do not work mainly the water system. During the day the voltage is adequate and things work, in the evening we are back to 145 ish. I want a light panel system so that my wife and I can easily see whether to use the water system or not. So red, yellow and green indicators to show red 145, yellow 170 and green 185 or round about. The display to be constant, I have Fluke meters but they all time out after a while. I can source most electronic components.

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


LED indicator

How should I drive an LED from a 38 volts power supply? The led wizard says I need a 1800 ohm, 2 watt resistor, but it also says' it'll disipate excessive heat. I recently took apart a surge protector and found that they drive an LED from a 120volt source by having a diode, LED and what appears to be either a 1 or 2 watt resistor. I need help driving an LED from a 38 volts power supply just as an indicator.

Topic by guyfrom7up 11 years ago  |  last reply 11 years ago


Low voltage health problems

Hello, I saw a great project on youtube, a water button, and gave it a try. it works, all it does is when one touches water, a led turns on, just a proof of concept. But what I was worried about, is if there are any negative health impacts of 3.3 v going though you and into the ground? The power is not noticeable, but still, I worry. ps. I did Google this, but couldn't find anything.

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


Low Voltage Higher Current?

I am having a strange problem on a USB peripheral.... it is a digital radiography sensor that overheats. I believe it may be due to the power supply to the motherboard, but I don't know for sure. I am ASKING FOR YOUR HELP in reasoning out what may be the cause. Anyone with computer/electronics experience, PLEASE HELP!!! I was told that my power supply is too low voltage, and that current is going up in the USB peripheral causing it to heat up. I always thought V=IR means that if voltage drops so does current. But in other places I read that if voltage drops, current goes up so that the wattage/power usage stays the same according to P=VI. So which is it? V=IR or P=VI ? If my power supply has too low voltage, will the current in the device increase to compensate? Or will it just have a lower current? Does it depend on the circuit and the exact electronics in the USB peripheral? Here is my SETUP. It is SIMPLE: Antec AR-350 power supply connected to a motherboard Asus P5N7A-VM in an ATX case. All I have otherwise is a SATA hard drive and a SATA DVD-ROM in there. That's it! Problem started to happen about 1.5 years after I got the computer. That is why I am thinking maybe it is the power supply, or maybe it is the motherboard?  The computer works fine in every other way! It uses Windows XP and has a wireless keyboard/mouse which also works fine. BIOS settings screen Hardware Monitor shows voltage for USB 5v reading about 4.9v, within tolerance. However, one of my USB peripherals is a digital xray sensor. It works ok a few times, then it starts to overheat and fail. This only happens on this computer. When I use another computer (like a laptop) with the same USB hardware it functions ok and never overheats. I don't have any problems on the other computer, even thought I am using the same software/drivers. I bought a different ATX case with a new power supply, and just moved the motherboard, HD and DVD over. Now the motherboard BIOS shows under Hardware Monitor that it is getting 5.2 V instead of 5v, so it is higher! Also the 12 V is higher (around 12.2v) and same for the 3.3V. All the voltages are HIGHER! So I have yet to test this new configuration with the USB peripheral sensor.  Could the motherboard be faulty? I did notice the motherboard looks "curved" with the area under the CPU sort of bulging out. However, with this motherboard you will see there is a huge heat-sink/fan that gets clamped over the CPU and that may be bending the board. Keep in mind the board works perfectly otherwise, so I am wondering WHY it would only affect USB for this one peripheral and not for the keyboard and mouse? Maybe the circuitry on the keyboard/mouse is more tolerant to low voltage? Would appreciate your thoughts please.

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


Railgun, High or Low voltage? Answered

Okay so i'm making a railgun, and need to get capacitors. Should i go with the ones in the 300-400 volts range, or somewhere around 15-50 volts? I would rather go low-voltage, as they seem to be alot cheaper.  Also, how would I go about making a charging circuit, schematics would be nice.

Question by LiquidLightning 8 years ago  |  last reply 3 years ago


Low voltage on Supercaps is a pain.

So, back when All Elecronics had them, I bought 100 of the 1F cooper (relatively high current) supercaps (2.5V), and likewise 100 of the Polyacene "batteries" that Electronics Goldmine is selling (0.6F, 3V, 20ohm.) But I've found the low voltages much more inhibiting than I thought it would be in actually using these. Have people managed to find good uses for these despite the low voltages?

Topic by westfw 11 years ago  |  last reply 9 years ago


Low voltage Push Solenoid

Hey everyone... I've been trying to find a DC push solenoid powered by 12V or less (I think 9V would be best). It needs to be able to push down on point and shoot camera trigger so I'm estimating about a half pound push minimum. I saw some time lapse modifications on the Make: photo pool. I'm going to do the same, but with simplicity in mind :P

Topic by trebuchet03 12 years ago  |  last reply 10 years ago


low voltage lighting problem

SkidMark2, or anyone who can help, I have a Portfolio 120 Watt Power Pack with 6 LED lights.  I don't know their wattage, but the power pack, lights and supply cord all came as a kit, so I'm sure they don't require more power than the pack can supply.  I'm NOT getting the E1 error message.  My problem is that the lights don't come on when turned on.  The power pack is set to "O" for switching on or off manually, but the house's light switch usually has to be flipped once or twice to get them to come on.  I've got both light sensors covered, so they should be sensing darkness and allow the lights to come on.  Any idea how to fix this so that turning the switch on once turns the lights on???

Topic by KenKlos 2 years ago  |  last reply 2 years ago


How can I make a low battery indicator for a 7.4 Li ion battery?

I'm hoping somebody can help show me how to make one or help me find a schematic for one as I have no Idea where to look, Google search is overwhelming and none of the results are for a similar battery (and are too complex). I really only need a circuit with one LED that lights up when the voltage drops, nothing fancy.     The battery is 7.4 V as stated and is Li ion.

Question by gravythis28 7 years ago  |  last reply 7 years ago


Low Battery Indicator for 2x AA Batteries

How would I create a circuit which turns on an LED when the voltage goes below 2.5V? I am using 2x AA batteries

Question by john8369 6 years ago  |  last reply 6 years ago


Voltage Regulator

EDIT: Anyone Interested please check below posts, this is one is obsoleteHello!I need a voltage smoother and regulator on my circuit(attached below)it is a modified shunt charge controller circuit.It converts the Tri phase alternating current to DC and feeds it into the circuit.The regulator will have to be attachable to the BATTERIES wire in the circuit.It should not consume more than 1v power on its own.My Vout to the battery currently is fluctuating.I will need the to be a stable 12v to charge the batteries. A potentiometer will have to adjust current.I will calibrate current according to my battery bank needs.Led 1 indicates 'charging' Led 2 indicates 'Dump'And Please forgive my circuit diagram design(it looks like crap)but works like gold.Also do NOT suggest huge changes to my controller for the regulator to work. Small suggestions to make it more effective,useful like change the zener diode power rating will be welcome.P.S- Its for my hydro project.Check it out at https://www.instructables.com/community/Help-Hydro-power/Kabir

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


Battery life indicator for 1.5V battery source

Hi guys, I want to make a simple battery life indicator for a device running from a 1.5V battery source. I would just need a red/green LED to light when the Voltage is above a certain limit (say 1.2 V). and to turn off once the limit is reached.. Is there any simple circuit that enables me to do this?

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


is it possible to use a low voltage controller at higher voltage?

I want to make a isolated switching power supply intended to drop and convert 220VAC to 12VDC, but the only available controllers in my area can only handle 100VDC at maximum. is there a way where i can use those switching controllers at 220VAC?

Question by codestroy7 6 years ago  |  last reply 6 years ago


how to run a high voltage motor with low voltage Answered

Hi there, I just wanna know how to run a 12v D.C motor using a 9v battery, is it possible by using  voltage and current doubler circuits? please help me, as i want this knowledge for a project of mine

Question by VivekM12 3 years ago  |  last reply 3 years ago


Ultra low voltage buck converter

I want to step down voltage from a 1.2/1.5v battery to 0.05V. Any advice?

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


Running LED on 1.2V rail

I have a board I am working on, and 3 voltages i'm working with: 3.3V, 2.5V, 1.2V. I want to have "Power OK" LEDs for each voltage rail. A look on digikey shows me that 3.3V and 2.5V wont be a problem, but there are no LEDs with a voltage drop less than 1.2V... and if there is, theyre probably expensive. So what is a simple way to have a "Power OK" led for 1.2V rail? p.s. I'm using all 0603/surface mount stuff.

Topic by samurai1200 9 years ago  |  last reply 9 years ago


help with changing transformer output of 8.5VAC 1200mA to 9VDC 1000Ma.

Howdy folk,    The Problem; I need some experienced assistance with changing the output of a transformer from 8.5VAC @1200ma to 9VDC @1000ma. Thanks in advance for any & all assistance.    The Back Story; The left channel went out in my PC speakers, which is designed for 230VAC, I had to destroy the woofer case to get to the transformer, and discovered that it outputs 8.5VAC @1200ma. I have another set of PC speakers (different manufacturer) that takes US voltage (110v) and steps it down to 9VAC @1000ma. I must first plug that transformer into a 100watt 230>110 step down (because I'm currently in the Philippines) and I want to get at least one transformer out of the "equation". I would just buy another system set up for local voltage, but I'm on a fixed income (until I can return to the States) that prohibits this avenue. I CAN afford some small components, but that's about it. Thanks again for any help. -Z-

Topic by Zclip 4 years ago  |  last reply 4 years ago


H.V. CAPACITOR CHARGE INDICATOR

CAN ANYONE HELP ME ABOUT HOW TO PUT A VOLTAGE/CHARGE INDICATOR on flash/High Voltage capacitors using LEDs - Thank You.....!!!!!!!

Topic by KITKAT69 10 years ago  |  last reply 5 years ago


Convert battery power to low voltage?

Is there an easy way to convert a security system sensor from battery (2 3V lithium batteries) to a wired low voltage line? I have pulled the cover off the sensor (image attached) and it doesn't look too complicated. Other options would be to convert it to POE or USB. Don't know if that's doable or practical. I'm building a house and have an opportunity to never have to replace those batteries, which are not on my "be nice to the environment" list. I have plenty of low-voltage in the house already. There is also built-in solar backup for 12-15 hours for power outages. Thanks for the help.

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


Low voltage, high amperage transformer?

Hi! I would like to make, buy, or find, a low voltage high amperage transformer to power an electrolosis cell. I like playing with the hydrogen-oxygen gas produced. From what I have read, I only need about 1.8 volts for electrolosis, so I'd like a circuit or transformer that could take the power from preferable a 9 volt battery and convert it to 1.8v at as high an amperage as I can get. Thanks : )

Question by fozzy13 10 years ago  |  last reply 2 months ago


Stepper motor voltage too low? Answered

I'm getting started with Stepper motors and I got one on ebay, it's MINEBEA NEMA23 2.5V/1.8 AMPS 1.8DEG/STEP (model# 23LM-C045-01H). I'm a bit confused by it's low voltage. Am I reading it correctly, it's 2.5Volts?  Stepper driver that I have requires at least 8 Volts (it's Arduino with rugged motor driver shield), so is it safe to drive with motor with voltage of 9 or 12 volts?  How would one drive such motor at 2.5VDC?

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


can anyone help me design a transformer for low voltages?

Can anyone help me design a step-up transformer where the input voltage is around 100 mV (AC) and to be converted around 2.5V (AC)?

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


Help! My low voltage, outdoor lighting wont light up - transformer error codes?

I bought a Portfolio 300watt transformer for low voltage outdoor lighting and hooked up a 100' 12 gauge cable (outdoor rated lighting cable) to it. Then I hooked up 4 low voltage lights (12volt 20 watts each). I plugged the transformer in to a gfi outlet that I ran out from the house. And turned it on. The little display flashes "E" and then "1" . The instructions say that the E means that there is a fire hazard so check the circut. So I unhooked every light except one. Same error. I hooked on a different light and unhooked the first one. Same error. Instructions say the cable needs to be under 250'. And the load less than 300w. I am there, except it won't run. Do I have a bad transformer or is there something that I am missing? Oh, and this is to light my haunt in my front yard, so I am running out of time! Thanks for any advice! Matt

Topic by mckeephoto 9 years ago  |  last reply 1 year ago


How can i adapt this low battery indicator for a 3V battery supply

How can i adapt this low battery indicator for a 3V battery supply so that the red light will turn on when the voltage drops to 1.8V? without the use of a pot

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


Wanted: 9 volt light sensor module

Calling all you that know and enjoy making circuits. Here is my problem.  This is too bulky of a solution with a relay switch and 12v battery pack. https://www.instructables.com/id/DC-Low-Voltage-LIght-Sensor-Switch/ What I would like is a 9 volt input and 9 volt output.  Actually, whatever the input should equal output.  So if I connect 3 v battery, I want 3 v output.  Right now I need 9 volt in = 9 volt out.  No Relays!!!  Simple and clean circuit board only. The LED can't be soldered to the board.  I need the capability of extending from the board with wire to adapt to my needed projects. On another note, if you know of something already on the market, please send a link.  I will be happy to make the purchase. OH... no modules that need a microcontroller.  Need a stand alone module. Thanks! Looking forward to hearing back soon. The Water Dog

Topic by DiyWaterDog 2 years ago  |  last reply 2 years ago



Reading the max voltage of a low duty cycle PWM?

How do I measure the maximum voltage reached by a very low duty cycle PWM signal without having to alter the signal. The multimeter shows no reading or gives a very brief wrong reading and falls back to zero. I don't have an oscilloscope. Are there any other alternative set-ups to measure just the voltage in this case. Please suggest.

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


low voltage photoelectric switch for led spotlight

I need help. I am making an led spotlight to mount on the flagpole and light up the flag at night. I have the lights from a 46 led flashlight. I've attached 2- 3.7v Li rechargeable batteries and a solar cell charger. Everything works great, except I want a photoelectric switch to turn light on and off. Right now, it is on a manual switch mounted to the pole. I cannot find and don't know how to build a 3.7v photocell circuit. I've tried 12v (all I can find except for 120v) and they won't work. I need to know what I need to make a 3.7v circuit/switch, and how to tie it in to the existing system. Can anyone help me? Thanks for any input. I am a novice, so be gentle. BJ

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


Arduino high voltage capacitor charge indicator?

I made a 330v gauss gun and wanted a way how to know when capacitors charge, at first i took an led and resistor, that worked but is kinda boring. I want to use arduino and lcd to display percentage which should look more cooler. How should I measure the capacitor bank voltage with arduino? Should I use voltage divider? or there is a better way?

Topic by spudziuvelis 3 years ago  |  last reply 3 years ago


how to construct a low voltage protection system using annunciator?

Hi in our college for our first year mini project , we were given a problem statement and based on it we have to find a solution , but i am not able to ,so here is the problem statement "low voltage protection system using annunciator generate 5volt power supply from 230volt ac and activate beeper when power supply is below 180volt.choose components with appropriate materials.list the important property based on which the material is chosen for the components .draw the waveforms of current and voltage at specific branches and node.find the laplace transformations ." so if any one  does come across some ideas please help i have my first review coming by so reply ASAP guys

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


K155ID1 chip showing low voltage between decimal pins and power supply. Is the chip bad? Answered

Hello, I turn to those who know probably a heck of a lot more about this than I do.  I've been trying to build myself a nixie tube clock, and everything has been going fairly well. I recently got the driver chips in the mail which convert BCD -> Decimal in order to hook the nixies up to a digital logic system like an arduino. I'm using a 12 V -> 180 V switching power supply for lighting the nixie tube. It is connected to ground on a computer power supply that I'm using to power the entire project. The 5 V rail on the computer power supply is connected to the Vcc pin of the K155ID1 chip as shown in the picture. I've connected the ground pin on the K155ID1 to the common ground of the computer power supply. I have nothing connected to the A, B, C, or D pins on the driver chip, which from what I understand should be the same as inputting the BCD number 0000 or just 0 in decimal. If I'm inputting a 0 as my number, the chip should output a 0 in decimal. From every single datasheet I've seen talking about this chip, that should mean that pin "0" (as shown in the picture) should become effectively grounded, and assuming that the "0" pin is connected to the 0 digit on the nixie tube, that should connect the nixie tube to ground, which should allow 180 volts to flow through the nixie tube, causing it to light up. Unfortunately, this is not what happens. In fact, nothing happens. Nothing happens no matter what pin on the driver the nixie tube is connected to. The only way I can get the nixie tube to light is if I connect it directly to ground, in which case, it lights up very nicely, but obviously that doesn't help with controlling it in any way. I took out my multimeter and measured the voltage between the 180 V supply line of the nixie tube and the pins of the driver chip, and every single pin (except A, B, C, and D) show a voltage of about 80 volts, which is not enough to light a nixie.  My question is, is there something I'm missing? I would think that the chip was bad or that I popped it or something. Heck, you could fill an electronics graveyard with all the chips I've popped over the years. But I've rebuilt this setup 4 times now, and I've attempted this following multiple schematics, and even switching the chip out for a brand new one 5 times. Each and every time the result is exactly the same. Either I'm overlooking something huge, or I just happened to buy 10 dead nixie driver chips. Thanks, in advance for any input!

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


Voltage Regulator Question? Answered

Hi Guys, Looking a bit into voltage regulators. When I'm looking at the wiring diagrams on the datasheets, most of them indicate that it requires a 30V+ish input voltage to work. I was hoping to get a small adjustable voltage regulator to run off the 12v range. I really don't need anything over 12volts anyway. Can I get this to work or do I have to find a power supply capable of providing 30V+ for the voltage regulator? I was looking at models such as the lm117 if it helps. Also, If I do need 30v+, where can you suggest I get that kind of power supply? I usually use 12v wall adapters. Thanks!

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


12v battery low voltage disconnect with relay? Answered

Could i make 12v battery low voltage disconnect with relay and resistor? I was thinking if put resistor in series with relay coil i could lower current so relay would barely work on 12v but when it drops to 10v voltage after resistor would be so small that relay would disconnect

Question by Cekpi7 2 years ago  |  last reply 6 days ago


Question about low voltage power supplies

I have several wall plug power supplies. The voltage on one says 12v 300ma but on my multimeter im getting 17 volts. Why is it 17v and not 12v?

Topic by Rob K 11 years ago  |  last reply 11 years ago


How to make a simple railgun(low voltage)? Answered

 I want to make a railgun. but i haven't any capacitors. I cannot decide power source. What i want is my railgun to be use low voltage power source(voltage < 400). and I want make a simple railgun. but I don't want linear DC motor experiment.(use foil). Can you recommend a simple railgun for me? I just have only 100$. (very low cost.)

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


Low Voltage High Current power supply

I am going to start off by saying I have no electrical backround, I can solder and am very mechanically inclined. I am wanting to use these as a laser power supply. I have a 24v 50a, a 48v 25a , and am getting a 5v 175a power supplies. I would like to do the voltages and amps adjustable with a potentiometer to go from 0- to their rated output. I see voltage regulators all over but they arent made for high current and usually dont make the current adjustable. How could I do this? Most laser diodes these would be used for are 2.2-3.5 volts.

Question by wby300 6 years ago  |  last reply 6 years ago


Low voltage AC power for thermocouple tube?

I am trying to make a readout for a DV-6M thermocouple gauge tube to measure vacuum. The tube requires 380mV (0.38v) AC across its filament to operate, and anything more could burn the filament. (I was reading up on this tube, and found the filament has a resistance of 18ohms but if you tried to measure it with a multimeter you could burn the filament). I have modified a 555 tone generator circuit, to accomplish this, and have measured the output to be 380mV AC with my fluke multimeter, and 0mv DC. When I put an LED across the output leads however, the LED is able to light which should take around 3v, which makes me wary of trying to connect it to my tube. what is happening, and is it really producing 380mV AC or is something else going on?

Question by Higgs Boson 6 years ago  |  last reply 6 years ago


Compact ight sensor switch with low voltage

Hi there,I've got a led light that's operated via a magnet, if it doesn't detect a magnetic field it turns on if it does it turns off. It's a led light for car door(check picture for reference) and uses 3x AAA batteries in my case 1.2v x3 (3.6v), if you use regular batteries it's 4.5vBy mistake I've order a tiny light sensor module 3.3-5v(check picture) which obviously can't be used as a switch, not in it's present form. While I'm good with solder, I've build an ebike, I'm a computer guy but when it comes to things like this like this make me feel powerless :( ..I 've used 12v light sensor switches but that's a different topic.So, how can I have a low powered light sensor switch that's compact and can save me from replacing the batteries frequent? ...the led light turns on even at daytime which has no point in doing that. I'd appriciate any help :D

Topic by Takisk1 11 months ago  |  last reply 8 months ago


Charge level indicator for small 4x AA Solar Battery Setup? Answered

Is there a simple way to build a charge indicator for 4 AA NIMH 1.2V 2000 mAh batteries? I thought a small 1-10 volt indicator would do it, but was told it would depend on battery type, etc...

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


inverter

I am making an inverter whivh converts 12 V dc to 230 V ac i am using 2 33 ohm resistor of 1 watt to connect the load on transformer whenever i switch on the ckt the 1 watt resistor are heating to much and multimeter does not show any voltage i am using 12 Volt dc 2.5AH battery as power supply what is the problem

Topic by AbhishekR2 4 years ago  |  last reply 4 years ago


Simple battery charge level indicator? Answered

I need to be able to see the charge level of a 12v rechargeable battery and want it to be as simple as possible. Would this setup work: 3 zener diodes (at different breakdown voltages 10, 11 and 12 volts for example) with cathodes connected to positive so that when the battery was above their breakdown voltage an led could light up. Here is a diagram:

Question by Scytheon3 7 years ago  |  last reply 4 years ago