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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

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

Dropping 1v?

I'm designing a circuit for a very high precision installation, and I need to regulate a 6VDC supply to 5VDC. I have looked at various regulators, but most seem to require at least 2v above the output. It also needs to be very precise, available in a 500mA package, and have a very low current draw. The less external components required, the better. Voltage dividers won't work as the battery will vary in voltage from full to empty.

Question by andy70707  

Battery holder drop voltages?

Recently my wireless mouse stop working, so I open it to inspect around, and I found out that at the connecting terminal between the battery holder and the mouse PCB, the voltage is only 1V (unplugged from the mouse itself) , but when I take the battery out to measure, each of the battery got 1.5V. And when I measure on the 2 metal ends (of the holder), my multimeter read 1.7V. So, what's wrong with it? Can anyone help me with this? It's really the first time I have a situation like this

Question by Mad Fox    |  last reply

DC Charger Voltage Drop?

Hey all! Long-time lurker, first-time poster. I don't have any instructables up on the site, but I have used many and I do have a biting question....currently, I am trying to create a USB car charger for my MP3 player out of an old CD Car Power Adapter. The MP3 player is a Creative Zen V, so it, of course, usually just charges on my computers with a USB to Mini-USB cable. In the next few months, I am picking up a new stereo for my car with an Aux. input and as I like recycling anything I can, I figured I could just make a charger myself so I could keep my player charged when I'm driving. The old CD Car Power Adapter in question has an output of 6V DC at 500ma. From my research, USB operates on 5V DC at a maximum current of 500ma, so the adapter I have seems almost perfect...? My question is this, how would I lower the voltage of the adapter from 6V to 5V? My second question is, I've read conflicting information on a number of, IS my information that USB 2,0 operates at a maximum of 500ma correct? If any of you folks would happen to know, and be so kind as to answer, I would be very grateful! I don't want to end up accidentally frying my player!

Topic by dagleykd    |  last reply

Circuit Design Questions - Voltage Drop Answered

Hi there, I'm working on a circuit which will include a 3v, .7Amp motor and three 20mA LED chips, with a maximum forward voltage of 3.8v. The whole circuit is intended to run off a 6v battery.In calculating resistance for voltage drop, I've figured out that resistance for the motor is 2.1 Ohms and then (by Ohm's Law Resistance = Voltage / Current) the resistance of each LED chip is 190 Ohms. Is this correct? It seems astronomically high.?

Question by Zahv    |  last reply

Drop 0.1 - 0.2 volts DC?

I am building a charger for my apple device, which requires exactly 5V (According to the internet) I am using a voltage booster to get from 3.7V to 5V but the booster outputs about 5.1 - 5.2V. I need a way to drop either 0.1V or 0.2V using a resistor or something. anyone know which one to use? Thanks.

Question by Tuckoguy    |  last reply

Why Solar Panel Voltage Drops When Connected The Radio? Answered

Hello, I own a Brunton Solaris 6 solar panel with the power rating of 12v 6W and short circuit voltage of 19v. We were living together just fine until I got a Yaesu Vx-8dr Radio. It charges on 12v 0.5A AC adapter. I decided to charge it with my PV but when I connect the panel voltage drops under 12v to 9v and Radio doesn't charge showing a External DC tag which indicates the lower voltage. The only time I get a charge with this setup is when the panel oriented to the sun perfectly in high solar conditions which is too perfect to sustain. I tried to wire it with 80 Ohm resister to limit the current but didn't help. How can I stabilize the voltage and also carry the solution in my backpack? Thank you for your attention and help.

Question by LongLongBow    |  last reply

Schematic for voltage drop (From 12VDC to 6VDC )

Hi all ^^ I am fixing a cassette deck ,but i am facing a problem. The original motor runs on 12 Volts DC ,but it is dead . I bought a new motor from the same company and with the same specifications (2400RPM). The problem is that it runs on 6Volts and not on 12Volts,  as the original is . Since the deck is old ,this is as close as i can get to finding a motor . The motor itself has a circuit within it ,that keeps the voltage and the RPM constant . So even if the voltage drops, this does not affect performance . If i use 12Volts ,I might destroy the circuit . If i use resistors to lower the voltage only ,then it does not have enough electrical current . Those motors need to draw freely electrical current ,since they draw more current when they are stressed ,so that they can keep spinning constantly at the same speed .This is why i need a schematic to lower the voltage ,but i don't know where to find one . The 12VDC comes from the main board of the cassette deck . I have a service manual that i can publish if needed . Thanks and best regards ,

Question by soundsmyth    |  last reply

Voltage increase after a 100 meter cable?

Hi all  So in one project we have an MDB that with a voltage of L1 : 243 L2 : 245 L3 : 243 , these values are normal in my country but the problem is that in the SDB that is around 100 meters away with around 4.5% voltage drop ( the schools electrician knew what he was doing apparently ) and the voltage at the SDB is L1 : 246 L2 : 250 L3 : 247 , i am a bit confused is why the voltage increased where the voltage drop is high and should be lower at the SDB than the MDB . 

Question by ShadiG1    |  last reply

Can I Limit Current Without Dropping The Voltage?

This kind of a noob question. I have a power source that supply 12V, 500mA. And the device I'm powering takes 12V, 140mA. How can I drop just the current (from 500mA to 140mA) without dropping the voltage? Since using a resistor would cause the voltage to drop as well. (Right?) Any help is greatly appreciated. Thanks.

Topic by gyromild    |  last reply

How to prevent voltage drop on solar phone charger?

Hello folks, I made a solar phone charger - cell (12V 400mA - at peak 5W)  and step down DC/DC converter R-785.0-1.0 (5V up to 1000mA). and I am using it as direct charger for my phone (no batteries). When the sun is bright, everything is fine and phone is being charged almost by 1A. When the dark comes, everything is fine - no charging but also no discharging of the phone to a solar cell. Problem is in the middle, sunlight but not so much. Voltage on cell drops to 6,5 V because converter wants more power and cell cant support that (output is still 5V but almost no Amps). Problem is, that charging circuit in phone is constantly switching on and off(as the load is pluged unpluged) and that can run down fully charged battery within 10 minutes. Is there any solution how to prevent that?- for example some kind of minimum current limiter? Or I saw using 555 timer as a charger controler, but not sure how to use it. Main goal is to prevent that oscilation. Many thanks in advance.       

Question by HanoCZ    |  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

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    |  last reply

555 timer cicuit

Hello guys I have a minor problem, I built a 555 timer circuit and it runs off of 6v. My plan is to use a 9v battery. Will the project be OK or will I need to drop the voltage and how would I go about that? Would I connect a resistor to the positive of the battery then to my project's input? Thanks, 

Topic by HavocRC    |  last reply

How Can I Reduce Current Without Dropping The Voltage?

Hello friends,                       i am making home automation with IR sensor , The problem is that the IR sensor sends random garbage values to arduino's serial monitor when connected to external power supply. The external power supply has output of 5v DC voltage and 2000mA current. The whole system worked perfectly when I take power from computer's USB port . The problem is how to reduce the current to 0 -500 mA of external power supply. thank you !

Topic by RakeshL1    |  last reply

Do I subtract the voltage?

So I was reading in my electronics for dummies book and it said there is about a 1.2 volt drop when using a standard LED. So, when calculating a resistor, with say a 9v battery, in my equation, do I make it R = (7.8 - 3) / 0.02 ? Instead of using 9v in my equation, do I have to subtract the voltage drop first?? Thanks! ~electricloser

Topic by HavocRC    |  last reply

When I apply a load to my voltage regulator, the output voltage drops. Why?

I'm trying to make a solar powered cell phone charger. I'm using a 5v 1A voltage regulator. When I have a dc input that is batteries, the voltage across the open output in 5.01v, as it should be. When I hook up a load, my phone, it stays at 5.01v. Now, when I hook up three solar panels rated at 3.5v 75mA a piece in series into the input, the output without a load is 5.01v. Then, when I ass my load, the voltage across the output drops to 4.7 something. What could cause this to happen? here's a picture on the two scenarios.

Question by phalanx447    |  last reply

6v 0.5a voltage regulator?

I need to drop down the voltage from 12v 1a to 6v 0.5a for a project but i dont know how to do this please help me !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Question by Andrew_48    |  last reply

Can I use a multimeter for measure voltage drop in LEDs?

I have a really cheap multimeter, but it has a "diode" position in the main switch. As the LEDs are diodes, could I measure the voltage drop for use in resistor calculations? My guess is "yes", but I'am very new to electronics... Thanks a lot.

Topic by Limadito    |  last reply

Does and LED's current draw depend on its voltage drop?

I was under the impression that an LED will draw whatever current it can get it's hands on, as my 20w LED (rated for 13.5 - 15.0v and 1500mA) would draw 3A when running off a 15.2v 2A ac adapter. Now that I've killed the 15.2v adapter, I'm running it off of one of 2 12v AC adapters, either a 1A, or the 2A one, and the draw is always 750mA (under the max possible supply from adapter). But when running this same test with a 10w 12v LED, the draw is 1A and 2A (max current supplied by each adapter). Does that mean that an LED draws a current based off its Forward Voltage, or is there something else I'm missing?

Question by Fuzzy3D    |  last reply

PICAXE battery voltage monitor

Does anyone have an idea of how one could get a picaxe to monitor its own battery source and light an LED when the voltage drops below a certain value. I am thinking that there might be a way to do it using a ADC input. Perhaps a zener diode could be used and the voltage above its threshold could be measured.

Topic by biochemtronics    |  last reply

Rectifying ac increases voltage?

I have a transformer that outputs 16 volts ac.  I built a 4-diode full wave rectifier and added a 4700uF 35 volt smoothing capacitor.  Now my dc voltage measures 21 volts?  I thought the voltage would drop because it has to pass through diodes.  What explains this voltage increase?

Question by aeronut01    |  last reply

19v to 12v without current drop?

I have laptop charger of 19V 3.42A(65W).i want to step down that 19v to 12v without any decrease in current.i need 12v 3.42+A  what is the simple way? can i use resistors to radius voltage without current drop? can i use LM7812C to get 12v 3.42+A there is ant way to get 12v 5A(65W)

Question by vina1991    |  last reply

Constant voltage AND constant current? Answered

Hi, smart people of the internet :) Is there a power supply or a converter that can be set on a specific voltage and current, and keep both constant at the same time? I looked at ebay converters like B3606, DPS5015, BST400 and the like. They all have constant voltage (CV) and constant current (CC) settings, but they can't do both at the same time. If for example the current being drawn is too high, the unit switches from CV to CC and drops the voltage as much as needed to keep the current constant. Is a simultaneous CC CV power supply even a thing? Thanks!

Question by Morgantao    |  last reply

How to cut down the Voltage???

Hello guys it's electricnewbie again, I have another newbie question that I think you can help me out with. OK so go easy with me since I'm a beginner. . . So, I have a laser/light (from walmart) that takes three 1.5 volt batteries that gives it a total of 4.5 volts. So, I want to hook it up to USB cable. Now, a USB cable supplies about 5.1 volts. How do I drop the current from 5.1 volts down the 4.5? How could I use the same principle in my other projects? Say I have a 9v battery and a 3.4v buzzer. I know how to use resistors with an LED. [R=V1-V2/mAH] Since I know the mAH of the LED, then I know what resistor to use. But how use that equation if at all on other things?? Thanks guys,

Topic by HavocRC    |  last reply

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    |  last reply

Voltage regulator Design Problem?

 Ah, voltage regulators. Easy Right! Not this one. I am making a voltage regulator like for an automobile regulator for a DC generator. (I'm replacing the old DC generator regulator on Pre 60's cars) A battery is charged from a winding on a Generator  (20V @ 60 Amps) A voltage sensor on the battery voltage turns on and off a switch driving the Field winding. The Field winding basically "turns on and off" the generator output. The battery is connected directly to the generator. (Why  and Why not is coming up) But when the Genrator's output is lower than the Battery voltage, current will flow back from the battery to the generator winding and discharge the Battery. So I need some isolation between the generator output and the battery. Alternators are easy since it has a bridge onthe output keeping the current from flowing backwards. Old regulators used a relay which burned out sooner or later. So easy, use a diode right? Just put a diode inseries with the generator to the batery. By the way, the "open circuit" voltage on a generator is about 200VDC No! The best diode I can find has a .7V drop at 60 Amps which is 42 Watts of heat to dissipate. Ahhh, so use a FET, They can get down into the milliOhms right? Except for the reverse polarity (and ESD) protecton diode always across the FETs defeat the purpose of a reverse polarity switch. So who out there is smarter than me? What goes inthe box marked ?? Any solutions accepted. Ungefahrt (now neither young or fast)

Question by ungefahrt    |  last reply

How to drop voltage on a 12v car battery to 6v for an old tractor of with 6v

I have an old tractor with a 6v system and i would like to put a 12v battery in it and for a couple other projects i would also like to know how to do this. thanks ron fancher

Question by flagman12    |  last reply

How do you drop a 14 volt DC source to a lower voltage?

This is for a fan inside my older stereo that I just replaced. It is quite loud and irritating spinning as fast as it does. I previously ran a 12 volt DC fan off of a 4.5 volt DC source and it was quieter and slower. So how can I lower the 14 volt DC?

Question by jmscfrk    |  last reply

Why do I get a voltage drop from my solar panels....? Answered

I am building my own solar panels and installing them as I go. So far I have mounted three 70 watt panels. I have a twenty amp controller and a 1500 watt pure sine wave inverter. With the array switched on and connected to the batteries (8 x12 volt 134AH) via the controller everything seems fine with a steady 13 -14 volt charge coming through. But when I connect the inverter the PV volts drop to around six and seven volts....The batteries are wired in parrale but not directly to each other. Instead I connected them to a buss bar hoping for equel drain and charge... I then connected the wires from controller and inverter to the bars... I thought this may have been the problem so swapped them all around having the controller wires to the battteries, then the inverter directly to the batteries... It made no difference and the voltages remained the same....I am hoping now that the reason maybe that I do not have enough panels to power the system and as I add more panels the voltage will rise...... l Any thoughts on this will be very welcome.....?

Question by SolarPoweredGardener    |  last reply

Voltage-capacity relation discharging an alkaline AAA battery?

Let's say I have a fresh alkaline AAA battery, 1.5V, 1200mAh. Also, let's say it discharges itself with 3% per year, just lying in the shelf. After one year, has both voltage and capacity been reduced 3%, or just the voltage? If not, how much has the capacity dropped then? I also wonder if the battery is being discharged the same  way, when in use? E.e. is the proportion between voltage drop and capacity drop the same on the shelf while in use?

Question by karolina81    |  last reply


I just designed (if it works out) a super efficeint Beam Solar engine that works at low voltages. Before I post it I want to ask a few questions to see if I need to revise my design. 1) MOSFETs work on voltage, no current, right? 2) Do MOSFETs have a voltage drop, like biploar transistors have a voltage drop of about 0.6 volts? EDIT: I got a new design that I want you guys to evaluate that doesn't use mosfets. It's incredibly simple and I want to know what you guys think. How it Works: The solar cell energizes the transformer coil while turning on the transistor. The transistor shorts the circuit and then the transistor turns off, then it repeats creating pulsed dc that drives the stepup transformer. I chose this design because there's very little components and there's no voltage drop across the transistor to the transformer. Theoretically this could run on as low as 0.7 volts, which is good for BEAM robots.

Topic by guyfrom7up    |  last reply

how to lower the current of a power supply but not the voltage? Answered

Ok i built this power supply, DC output.  it puts out about 60volts at a reasonable high amperage(i have been able to do light welding with it) is there a way i can lower the current with minimal voltage drop? if so how?

Question by twenglish1    |  last reply

Voltage Sensor/ Regulator (with switching capability)

Hello All!! I am looking for help! I have a invention that deals with 12 VDC battery banks. I have a series of batteries that I would like to charge with a small solar panel. I need the solar panel current to be able to go from battery to battery as voltage levels drop below 12.55v and when they rise above 13.75v. I know this control-sensor-switch can be built. I just have no idea how to go about it. I also realize this site has some very smart people that use it and would appreciate any help. I am willing to give a $ reward to someone that can design this controller with a intructable video. Any takers?

Topic by starfishenergy    |  last reply

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    |  last reply

Is there such a thing as a switch that will close the circuit if the open voltage drops below 12 volts dc.?

I am using a LiPo battery to power a bike light and the battery can be permanently damaged if the voltage drops below 12 volts.  Is there a switch I can wire in parallel which will cut power if the voltage drops too far.  

Question by Noblenutria    |  last reply

Question: I made a power pack of 18650s with protection board. Is voltage drop normal?

I made a power pack using 18650 batteries from an old laptop. All batteries tested individually are good. 4 batteries in 2S format. I used a cheap 2S 3Amp rated protection board I got on Ebay from China. I correctly connected all the terminals and properly soldered, B+/B- to the +/- of the final ends of battery and BM to the middle.The voltage measured directly at the battery terminals (at B+/B-) is 8.4 volts but at P+/P- (the input/output terminals of the board) it measures 7.5. Which means this board will not produce more than 7.5 volt usable voltage even when the batteries are fully charged to 8.4. Is that expected and normal? or is there a problem with the board.Thanks for help.

Question by ju1234    |  last reply

how can i drop 1A dc to 500ma dc? Answered

I have an AC-DC power supply with voltages of DC 3 - 4.5 - 6 - 7.5 - 9 - 12V and 1000ma and i want to drop this down to 500ma!

Question by thecookiemonster    |  last reply

How to reduce current without reducing voltage

Hi, I'm working on a sign that basically has LEDs as letters. I have 140 LEDs that I'm planning to put in series of 4 each and then 35 in parallel. My problem is that I was mailed a transformer that outputs DC 12v 1.25 A (Actually 12.3V 1.4A). The current is too large for what I need for the LEDs and I don't want them to burn out too quickly so how would I drop the current without affecting the voltage? Any advice would be appreciated, thank you!

Topic by ytan10    |  last reply

How does the num. of turns & voltage on the primary translate to an ideal voltage on the secondary?

In electronics, one of the things that has been the most confusing to me is the physics behind transformers. I have learned of that stupid formula a while back, where the ratio of turns is proportional to the voltage ratio and inversely proportional to the current, however, I know from reality that it is no where near that straight forward. As far as I can tell, it is a bunch of BS. Anyway, I want to know what the REAL story is, how the AC current going through the transformer is related to the magnetic flux through the core, and how that relates to the output of the secondary. What seems counterintuitive to me is that more windings on the primary should yield to a stronger magnetic field in the core for a given current, which means for magnetic flux (???) which seems like it should yield to more induced current in the secondary. Is the answer related to inductive reactance (more turns = more inductance = more inductive reactance = higher impedance at a given sinusoidal freq. = less current per unit of voltage?) Note: If you have a good physics and calc background and understand it to heart, pls do explain. However, I am currently only nearing the end of calc 2 w/ absolutely no formal education in physics, so I may have some difficulty with wank terms and vocab. (a.k.a. do not try to show off how many terms you know attempting to explain things in the most complicated and technical way possible.) Also, any good tutorials online that go into depth into the topic? ----------------------------------- The reason I want to know these things is that I wasn't to build a good 6A 0-+/-15V dual isolated channel linear power supply with many transformer tabs so I can keep the voltage drop on the pass elements as low as possible at variable output's so huge $$$ heatsinks are not necessary due to lower low power dissipation. (I have mostly figured out the LPS circuitry, but have not found a suitable Xformer online.) I can get the laminated magnetic cores needed relatively cheaply, however if I have to do some custom windings, I want to make sure I do not choose the wrong number of windings for the core. (obviously one turn on the secondary and 5 turns on the primary will pop a breaker @ 60Hz... )

Question by -max-    |  last reply

Reducing Current While Leaving Voltage the Same

Hey, I have a power source that puts out 5V at about 2A. I need to reduce the current to 1A while maintaining 5V. How would I go about doing this? I thought about a resistor, but since the voltage drop is 0, how would I calculate what value I would need?EDIT: I was also looking at regulators, like this one. It says it limits current to 1A, but I'm not sure if it would be useful for what I need...;=MCP1826-5002E/AT-ND

Topic by msh21    |  last reply

How can I add voltage to a car electrical system? Answered

I have a 14 volt car electrical system (standard) How can I increase the voltage back up to 14 and prevent it from dropping due to car audio? Adding a battery will only provide a small amount of time and therefore not provide a well made solution.

Question by getgcs    |  last reply

How to drop 9 volts to 3 volts at 32 ma

Hello, I am a new B here. I would like to use a 9 volt battery to power lights for my RC car. The led lights operate at 3 volts 32 ma. What size resistor will I need to make the voltage drop. Will this also control the current so I do burn up the lights. The lights are somewhat expensive so would like to get it right the first time. Thanks for anyone's help.papadewey221

Question by papadewey221    |  last reply

If I put 5v in a 5v voltage reg, will 5v come out?

What kind of voltage drop should I expect if I put 5v in a 5v reg?

Question by nepheron    |  last reply

what are possible causes and solutions for low output voltage on a HID ballast? Answered

HV starting pulse is normal, but then output voltage drops to around 1.5-2VAC.  no obvious damage to PCB or components within.

Question by    |  last reply

How can I modify this circuit to sequentially turn on LEDs in parallel, while avoiding voltage drops? Answered

I have a single pole, 12 throw rotary switch which I want to solder to a set of LEDs so that rotating the switch clockwise lights more LEDs as follows: 1 = 1 Red LED 2 = 2 Red LEDs 3 = 3 Red LEDs 4 = 4 Red LEDs 5 = 5 Yellow LEDs 6 = 6 Yellow LEDs 7 = 7 Yellow LEDs 8 = 8 Yellow LEDs 9 = 9 Blue LEDs 10 = 10 Blue LEDs 11 = 11 Blue LEDs 12 = 12 Blue LEDs Since there will be a voltage drop across the diodes, the LEDs at the start of the chain will get progressively dimmer, and increasing the voltage would blow the LEDs in shorter chains. One modification I know I could already make would be to not use the first 4 diodes on the yellow LEDs, and the first 8 diodes on the red LEDs, as a minimum of 5 yellows and 9 blue will be active for each position. This still leaves a maximum of 3 diodes in each chain, which I still think would cause the lights to be much dimmer. Another solution I can think of is to have multiple wires coming from each terminal of the switch, each with their own diode, which would ensure all active LEDs had the same brightness (I'm not sure if this would cause the whole chain to be dimmer than shorter chains or not). The downside is this would need  31 wires rather than 13, and that's only if I bridged together all the shortest LED chains of each sequence: individual wires for absolutely every position would mean 79 wires+diodes). To put this in context, I want to create the health bar from Dead Space 3: If you can suggest a way of improving the circuit, or totally re-designing it, it'd help me loads! Thanks!

Question by Shadow Of Intent    |  last reply

Can i use voltage regulators to reduce a 12v system to 6volt?

Can i put about voltage regulators in serie to drop 2 volts at a time to reach 6v?if so how can i know the rating of the regulators?

Question by fjchorn    |  last reply