Voltage help

Hello I am new to electronics I am having trouble designing a circuit that lowers VDC as ground resistance increases and raises as ground decreases every circuit I've built works backwards. I am working with 5vdc any help would be much appreciated thanks

Topic by Ed69   |  last reply


Voltage regulation

I have a solar charge controller (Velleman SOL4UCN2) that outputs 12v, 6v and 3v. But I need 9v and I'm not sure how to get that.

Topic by pless84   |  last reply


Voltage regulator?

I need to know how to build a 12v-5v pulse regulator for my fuel level sending unit/gauge in my truck. I would like to know what parts to buy and the order of everything. Thank you in advance. Daniel

Topic by gungfudan   |  last reply


Led voltages

I have a small pile of salvaged LEDs from various burned up electronics (flashlights, old stereos, etc) and I am wondering if there is any way to figure out what the voltage requirements are for the led. if anyone has an idea how to find this out it would be of great help.

Topic by danlab   |  last reply


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?

Topic by JonLoder   |  last reply


5 voltages?

What are the top 5 voltages we deal with in the U.S.?

Question by erik30   |  last reply


Voltage regulator? Answered

Does a voltage regulator IC (e.g 7805, LM317 etc) still draw current when there is no load?

Question by .Unknown.   |  last reply


Voltage Divider?

I will need to convert 5v to 1.2v... I chose 10k and 2k because 10k/(10k+2k)=1.2v. Would these resistors work for this?

Question by lorogan   |  last reply


Voltage Drop

I have a 12v led bulb, I need to connect the led bulb to 12V rechargeable battery  and connect bulb for  long distance from battery and i connect the bulb i won't  work, i think the voltage drop would be the  answer and how can i solve that????

Topic by rshan   |  last reply


laser voltage?

I have a laser diode that needs between 3.7v  and 4.2v to run, http://www.laserlands.net/gd-ms-200mw-green.html and i plan to run it of an arduino (5v). to reduse the voltage i have calculated that i need a resistance of aproximately 1.333ohm. is this necessary/is there a bether way to do this? thank you in advance for any answer!

Question by ludvig.risan   |  last reply


Fluctuating voltage?

I am trying to build an ammeter using a 100:5A CT and a pic16F716 and display the value using 7segments. However, The voltage I get from the CT after rectifying it using an OPAMP still fluctuates between 4.8 and 5.4 .  I don't understand what is causing it to fluctuate that way. I will attach a picture of the circuit I am working on.

Question by IndiraK2   |  last reply


Voltage question

I'm building a electric anchor for my boat. I'm using an electric actuator thats rated at 24v to 36v. I need to step up the power. my boat is only 12v. I was going to use a stepup converter. Found one  12v in and 48v out. Is there a way to control the voltage so i can tune it down to 36v. Also would there be a big difference running it 24v verus 36V?

Question by kurt1968   |  last reply


Voltage for NiChrome?

Will 2.5 volts be enough to heat a small segment of NiChrome wire up to/over 100 C? If it helps, the power is coming from a 8.1 kJ 2.5v 2600 F super capacitor which can unload very quickly.

Question by LiquidLightning   |  last reply


LED Voltage? Answered

So recently I had an idea to make a steam gun by heating steam with a NiChrome wire driven by a 9v battery, anyway, to keep it safe and so i knew when it was on, i decided to add an LED to the circuit. I went to http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator to see which resistor i needed. From what i understand, the resistor limits the CURRENT across the circuit. So, what i want to know is whether the Led will work with the first attached circuit and not bun out from the voltage, and whether the nichrome wire and led will work in circuit 2. EDIITTT: Well, after a few answers, i'm realising i cant run this off of a 9volt, so, what small powersupply could i use?

Question by LiquidLightning   |  last reply


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   |  last reply


will this really regulate voltage?

Will this really regulate voltage?I would think that voltage could just flow arround the capshttp://electronics.howstuffworks.com/digital-electronics4.htm

Topic by kendallickes   |  last reply


voltage multiplier bath

I saw the voltage multiplier Instructablehttps://www.instructables.com/id/High-Voltage-Multiplier/and I'm wondering if it's necessary to put it in oil.My capacitors would be severely under volted (that should be a word, the past tense of volt, LOL) and the diodes wouldn't even be challenged.

Topic by guyfrom7up   |  last reply


voltage vs uf?

If you were building something, say a coil gun, would it be best to use a bank of higher voltage (300+V), lower uf (80-120uf), or a few capacitors of say, 1000uf 50V or lower?  

Question by Spaazztik   |  last reply


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   |  last reply


High Voltage shenanigans

I thought it was about time to post these videos ive made so i did! my very first forum post!

Topic by The 4th Doctor   |  last reply


Green Led voltage?

I picked up some green leds at a surplus store today. I've been assuming that they run on 1.7 volts, is this about right?

Topic by sabeen557   |  last reply


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   |  last reply


Small Voltage Regulator

I am looking to buy or build a small voltage regulator that can fit in an O gauge electric train engine. It needs to have a 18-20 volt AC input and 10-12 Volt AC 1 amp output. I would like to buy one already built, buy a schematic or a schematic with the parts to build. Thank You

Topic by frankv6   |  last reply


Increasing DC voltage

I need to increase the voltage of a battery from ~30v to ~230v, the only way i can think of doing this is somehow pulsing the DC rapidly to create a sort of "pseudo AC" then using a standard transformer to increase the voltage, followed by the standard rectification process. My problem is how to pulse the DC (bearing in mind the pulse will probably need to be in the order of kHz, and the device being powered at 230v has a power rating of 400W) and how to after the rectification process implement a pwm system. In addition, the method of increasing the voltage strikes me as extremely inefficient, so if anyone has any other ideas I would be very great full. Thank you for any help you can provide.

Topic by csharpdeveloper   |  last reply


Micro High Voltage

I'm going to attempt to make a super micro tesla coil that is 100% contained (unless it runs off of like 12 volts dc, then I'll use a wallwart). Of course, one of the i biggest problem is the power supply. So this is what I'm asking, what's the best way of ramping up the voltage? A tiny toroid transformer? An inductor that gets pulsed? Voltage Multiplier? Something with static electricity? Some type of Inverter? Using Greinacher Cascades? A marx generator hybrid? Other stuff I havn't heard of?

Topic by guyfrom7up   |  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


High Voltage Ground

I'm starting to work with high voltages again, but for real this time. I just built an ignition coil driver, using a 555 (and I got an ignition coil), but my 555 broke (the texas instruments ones can only drive 15mA, oppose to the normal 200mA, oops) so I have to go buy one today. My main question is what to use for ground, whether it be for an old screwdriver for arcing sparks or the secondary of a tesla coil. I was originall just going to use the 3rd prong of an outlet, but somewhere on the internet I heard this could destroy all surge protected power strips and destroy all plugged in electronics at your house. I, of course, do not want this cause... well... I'd be screwed. Is this true or not? Can I use the 3rd prong?

Topic by guyfrom7up   |  last reply


Voltage regulator for laptop

Hi there. I have a problem for which I'd like some opinions: I have a PB laptop which has fried its inverter for the LCD due to the input voltage towards the inverter being too high (19v while it should be 12v and can only endure upto 13v). Most PB models have this problem. I looked around and some people suggest making a voltage regulator with a 7812 and some capacitors that gets its power directly from the input of the power adapter on the laptop (19v, 6+ amps). But since I am not really that into electronics, I have no idea if this will work, especially towards the heat that comes with the 7812, will it be high? The inverter needs around 0.5 amps input current. Others suggest a setup with (zener) diodes, but I have no clue how to start on that. Anybody have a suggestion? Many thanks.

Topic by .conne. 


Help with voltage/resistor

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

Topic by pennsteve   |  last reply


Transistor Swithching Voltage? Answered

Looking at this data sheet: http://www.datasheetcatalog.org/datasheet/stmicroelectronics/4136.pdf How much voltage has to be applied across the base and emitter to switch on a "TIP 3055" transistor? The V-be row is the only thing that looks like it is telling about that, but I don't think that's what I'm looking for (mabey it is?).

Question by Jaycub   |  last reply


phototransistor for high voltage

Before the begining sorry for bad english I want to make laser tag with electric shock when hits This is circuit of taser what I want to do is remove the switch and replace with wire so that the taser can charge automatically then I want to put a phototransistor(that react to red laser) to the poles(where you get shocked when touch them together) but because the both poles are attached to bodies the taser can't be charged so I tried to block one side of pole with phototransistor but when I touch the two poles phototransistor burned(?) and I got shocked in this case what can i do?

Topic by hyeok205   |  last reply


-5v Voltage Regulator

I want to make a -5v Voltage Regulator... Does anyone know if I replace the 7805 regulator with a 7905 would that be enough, or would the capacitors have to be different values?5v Voltage Regulator Schematics

Topic by mrshow555   |  last reply


AC Voltage Attenuation?

Hello, All- I am making my second version of the "Tube Lamp." Others have managed to wire in these neat-looking old analog meters on theirs, and I thought that would be something I'd like to try. I bought a couple 1-10VAC meters from fairradio.com... The problem is (besides the fact that I am an electronics idiot) that obviously if I try to wire in this particular meter to normal 110 AC, the meter will blow up. Is there a way to attenuate the voltage coming out of the dimmer to "play nice" with the 1-10 VAC meter? I suppose I would need to divide the voltage by a factor of 10. How would I step down the voltage to the meter only, while supplying the bulbs with the proper voltage? Any help would be appreciated!

Topic by 40percentrobot   |  last reply


Plasma disc voltage? Answered

Hello! I've seen a few of these plasma discs and was wondering if anyone know what voltage these things generate? I know its some high-frequency ac voltage powering the disc, but does anyone have a rough estimate? Just curious. I've been meaning to take one apart, but I don't think my multimeter could withstand a  shock from it. (Rated for 600v).  Pic of a plasma disc: http://image.made-in-china.com/2f0j00HVatueUbBTGl/Plasma-Disc-J-LP200-B-.jpg Thanks!

Question by transistorguy   |  last reply


Transistor Voltage Inverter

I am a newbie and was hoping someone could assist me. Given the following schematic which takes a voltage of 12v and considers it off and a voltage of 2 volts and considers it on can someone tell me what changes would need to take place regarding capacitors and resistors (if any) to account for 20v instead of 12v? Meaning that when 20v is considered off and 2v is considered on.

Topic by TimothyE2   |  last reply


Transistor Voltage Inverter?

I am a newbie and was hoping someone could assist me. Given the following schematic which takes a voltage of 12v and considers it off and a voltage of 2 volts and considers it on can someone tell me what changes would need to take place regarding capacitors and resistors (if any) to account for 20v instead of 12v? Meaning that when 20v is considered off and 2v is considered on.

Question by TimothyE2   |  last reply


Voltage follower for the INA125?

I need to use a voltage follower that runs off a 9 v battery (actually, two batteries so +- 9V is available), from the output of a Burr-Brown INA125 amplifier to the analog input of a DATAQ data acquisition unit. The DATAQ is running at about 1000 data points per second.  Is there a particular op-amp that would be useful in such an application?  Or would something besides an op amp be more useful?  Thanks!

Question by Prfesser   |  last reply


voltage regulators and supercaps? Answered

I have 12 .22F 5 volt supercapacitors that i bought recently. Ive been thinking about making something like the Mintyboost from Adafruit but am unsure on how to do it with supercaps. Any help is appreciated as this is stumping me pretty well. thanks, bud

Question by budhaztm   |  last reply


Voltage Regulator circuit

I am trying to power Bluetooth module and the Arduino using a 9V battery. So tried to use a voltage regulator (KA7805) with 25volt 100miro farad and 63V 1 micro farad capacitors. I checked the circuit connecting these components using multimeter, it showed 5.06V as the output. But the problem comes when I connect the Bluetooth module to this output, which turns off after quickly. I checked the voltage at the bluetooth which is reducing quickly from 5V-2.5V in a matter of seconds and since the operating voltage of Bluetooth module HC-05 is 3.6V-7V, it turns off. I am not clear why this circuit behaving this way. Same output when I connected to the Arduino, it works seamlessly. Please let me know what are the mistakes that I need to rectify for this work. Thanks in advance

Topic by Bhanu Kishan 


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   |  last reply


Supercapacitor Voltage Draw

If I am charging a super capacitor with buck converter, that is a 1 amp, 1-18 volt output, and the capacitor is rated for 2.5 volts, how do I stop the buck converter from feeding it more than 2.5 volts? When I attach the capacitor to my digital power supply, it starts charging, and the voltage slowly increase to be more than 2.5 volts, at which point I turn it off. I was wondering will it draw more than 2.5 volts from my buck converter? If so how do I stop it?

Topic by merlinj   |  last reply


different voltages for leds?

Leds on ebay,at different online shops and,found in old electronics.can any led work with say, 12 volt car power,[dc, with the appropiate resistors]disconnect it and hook it up to ac house[again,with the appropiate resistors]current?should i look for certain voltages sources when buying or just strive for the voltage the led calls for?also,is 12 volt dc car power the same as 12 volt computer power?the fans and such on computers [as far as i can tell]run on 12 volts.might seem like a silly question,but then i'm REALLY not very conversant with all this led tech.in other words,can i run an led off any[ac or dc]current as long as i use the correct resistor?thanks for schooling me on this.i'll be forever gratefull

Question by frankentrike   |  last reply


High voltage NOT gate Answered

I am creating a circuit and I need a not gate to run 20 3v 20mA LEDs. The only problem is that to run all of those LEDs (4 series circuits in parallel, if that will help) I am using 18 volts (2 9v batteries in a series). My circuit is compact (,think fitting inside an Altoids container) so a relay wouldn't work. So I need a high voltage way to make a not gate. I can read schematics if that will help you explain it, but I do need you to mention the ohms of the resistor. Thanks a million!

Question by GenAap   |  last reply


Measuring LED Voltage

Greetings... I have quite a few "salvaged" LED's, none of which have I the slightest clue as to their voltage. I have attempted to measure them using the diode setting on my voltmeter with dubious/mixed/questionable results. Although the measurements are momentary (the reading is barely of sufficient length to note), I can usually arrive at a value. Unfortunately, when I repeat the measurement on the same LED the reading is invariably different. For example, I just measured the value of a random LED (green) and came up with the following: 1.3. 1.4, 1.8, 1.6. I've rounded the values to the nearest decimal point. Are these values through voltage? Are the differences between the readings significant or should I use the minimum when calculating resistor values? I'll, no doubt, have a few more question later on. I appreciate your elucidation on this matter... Best to all, hassi

Topic by hassi   |  last reply


Vacuum pump voltage?

Today I was dumpster diving and i found an old vacuum so i decided to take the pump out but i made the mistake of not checking what voltage the vacuum runs on, because it also had a spinning component at the mouth of the vacuum. I think the pump works fine because i noticed that tube connecting the mouth of the vacuum and the pump was broke. Is there anyway to find out what voltage it runs on? would standard 120 be ok?The markings on it say 81 b-9 ECP 6500-240 HPU+ 60hz HD10 120 vac 07:07 does that mean it will work off a standard 120 outlet?update: What I am going to do with this motor has been decided. I will be attaching it to the back wheel of my bike with a car battery, i will install some type of switch on the handlebar or add something like a dimmer switch, this would allow me to have the motor on if i want, and i can adjust the speed. Please help fine tune this idea.

Topic by astrozombies138   |  last reply


Rectification of line voltage?

I need to get 230V DC for controlling the brightness of the bulb using a mosfet transistor. The problem is that the rectified line voltage'll get 230 * sqrt (2) = 325 V .. it is too much. I didn't find a transformer AC / AC 230/160 V or step-down IO DC / DC 320/230 V on a market. How can it be solved? Sorry for my english. Thank you for answer.

Question by AntonínO1   |  last reply


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   |  last reply


Batterys and Voltage Question

Hello, im new here (made my account 2 hours ago) so hope i have asked this in the right place.im planning on building a speaker rucksack, i.e modifing some speakers into a rucksack. now the speakers i have chosen to mod into the bag are mains powered but i want to power them with batteries.The speaker adaptor looks like this...http://i40.tinypic.com/71h9at.jpgand reads "Logic3 AC/DC ADAPTOR CLASS 2 TRANSFORMER, INPUT : 230V 50Hz, OUTPUT : 15V 1200mA MODEL : D57-15-1200"I have 2 batteries which combined i think i could use to power the speakers, they look like this...http://i43.tinypic.com/3321buv.jpghttp://i39.tinypic.com/1691c78.jpgSmall light coloured one reads "VALVE REGULATED RECHARGEABLE BATTERY, HGL3.2-6, 6V3.2Ah/20HR, CYCLIC.Big dark coloured one reads "SEALED MAINTENANCE-FREE RECHARGEABLE BATTERY, UL3.4-12(12V,3.4AH/20HR).As i understand it the speakers run off of 15V 1200mA and the batteries together will produce 18v. this is too much power for the speakers so i need something to step down the power to the right voltage for the speakers. what do i need to do this? a certain component, resistor maybe?any help would be greatly appreciated, thanks :)

Topic by superrob   |  last reply


What is the use of negative voltage. if it do same as positive voltage? Answered

Some where we can see that the circuit only require negative voltage. WHY Only Negative IF positive voltage can do the same

Question by engineer.arpit   |  last reply


Need a 100v voltage regulator?

So what I am trying to do is make a variable power supply from a computer PSU, I've done thise before minus the variable part. I need a voltage regulator that will limit 200 or more volts to 100 volts DC. I also need different variable voltage regulator that will allow me to adjust this from 0 to 100 volts, they usually have a circuit in the datasheet that uses some resistors and a potentiometer. So, are there voltage regulators like this? If not what is another way to do it?

Question by XOIIO   |  last reply