Search for efficiently changing power supply in Topics


Flash Power Supplies

I don't have a lot of money to spend on stuff at the moment. What I do have is flash guns. Four of them in fact, three of which can be fired with triggers. Now I could invest in 16 rechargeable batteries. Or should that be 32 in case I run out? And a crap load of chargers.  And extensions cos we have no spare sockets in our house. But that just doesn't seem right to me.   Heres what I propose : 1) make some dummy batteries from wood with wire running through the middle.   Three of these go in each flash to carry the connections  2) a fourth dummy battery carries wires out of a small notch in the battery flap door 3) said wires are connected in parallel to a large rechargeable battery - I reckon a 6v from an old British motorcycle (fast draining) or from a granny wagon (deep cycle) should do the trick.  4) when I'm done shooting I charge this single battery from the mains charger I have (does 6/12v) I figure 4xAA batteries at 1.5v = a 6v battery, bu extra size should last longer, be more convenient than carrying around dozens of AAs and changing them and if I want to use AAs when our and about I still can   Any reasons tho wouldn't work or I shouldn't do it?

Topic by ohowson    |  last reply


¿What power source is more efficient?

For a project I have to decide between a mechanical generator (I.E. one attached to a bike's wheel) o an array of cheap solar panels.Anyone has experience with this? What is your advice?I only need to supply power to recharge four generic AA batteries once a day.Thanks!

Question by Daniel FranciscoD1    |  last reply


Changing DC voltage and amperage?

I've been looking into HHO units and the most efficient voltage is 1.5 VDC but the units pull 30 Amps.  All the converters and modules seem wasteful while I feel there is a direct way to create this supply with minimal loss from battery supply.  Resistors seem to be the most efficient but what resistor can turn 12V into 1.5V while delivering 30 Amps without burning something out.  I'm contemplating a bank of resistors all on separate leads and tied together in a parallel combination so the 30 Amps are split along many lower amp rated resistors.  I just don't know enough about DC conversion to know if amps will become volts or just get lost to heat dissipation.  An HHO unit relies on the highest efficiency current supply to perform correctly and save my gas.  The units are out there but not this fine tuned system I want to build because 1.5V at a 30 A draw from a 12V car battery is hard to do without wasting the gas in just converting the ideal power supply.  I've heard talk of using diodes as well.  Is a diode or resistor setup more efficient than a PWM?  Could I combine diodes and resistors for better efficiency?  I've been searching the web for info but it just confused me more as nothing I've read comes anywhere close to what I'm trying to do.  Those I've read about that try to build the most efficient power supply end up burning up their components by pushing them too hard while instructing others to do the same.  There has to be an efficient way to create that ideal supply current without much loss.  Could it be run straight off my alternator since it produces AC before the voltage regulator converts it to DC or would a second regulator just waste more current than resistors and diodes from the 12V battery?  Any advice or info would be greatly appreciated.    

Question by bmac30    |  last reply


Will a computer power supply run efficiently on a 12V power inverter? Answered

I am planning to buy a modified sinewave inverter just to power some basic stuffs from a car, but one of my main problem is that i want to power 2 sensitive devices on the inverter. I have a 450W computer powersupply Will it run smoothly or will make hissing noise or will get fried after minutes of use same goes with a 19" inch LCD screen some help here would be  much appreciated thanks

Question by ARJOON    |  last reply


DIY power supply for HDDs

Hi there, I'm thinking of making my own external harddisk to keep on my desk. You know: for backups, etc. I'm (probably) going to fit 2 HDDs in there. The HDDs need both 12V and 5V and since I don't want to connect two adapters to it I need to change the 12V that goes into the box to 5V. I've done some research and I think I got it figured out... I think a 78s05 condensator should do the trick. Side note: the disks need 0.9A and 0.72A on 5V (=1.62A). I've attached a picture where I show my idea.... any thoughts and most of all WOULD THIS WORK? Kind regards, Niels

Question by Niellles    |  last reply


Candles with external power supply

Hello everybody, hope somebody will be able to help me out or point to a right direction. I have about 40 battery candles that I have to change batteries every month. I was wondering what could I do to convert them to candles with power supply connected to a regular outlet so there wouldn't be a need for batteries. I know there are special candles with external power supplies but the ones I found are in thousands of dollar. These candles go inside large candles made from wax that is a reason why I need long wires. I have attached pictures of the candles. What I would like to do is to connect them with long wires to one or multiply power supplies connected to regular electrical power outlet. One candle holds 4 AA batteries. Could someone recommend what power supply and parts I should get to make this happen? Thanks.

Topic by gointern    |  last reply


Do some usb power adapters supply 6.5 volts?

I took a 12 volt usb car usb adapter apart and wired it to a switch and a panel mounted female usb plug.  The power supply is outputting 6.5 volts.  This has me worried because I thought USB power was always 5 volts.  Maybe once I plug something into it the voltage will automatically change to a the right voltage and current required by the device.    Also, this adapter says it is only compatible with Iphones.  Does that mean anything else usb powered would not work? this is the adapter http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item;=220702089964&ssPageName;=STRK:MEaWNX:IT#ht_2128wt_1141 thanks

Question by Noblenutria    |  last reply


Supercapacitor for power supply design?

Hi I am new to electronics but I have studied the basics and the logic. I have 6 3000 farad supercapacitor from Maxwell(not the boost cap one) with a power rating of 3 watt- hour, so each capacitor holds about 10.8 kilo watts(3 watt x 3600 seconds= 10,800 watts). So I have been wanting to make a power supply out of these and two types have ran across my mind: 1. Turning them to a voltage multiplier type of circuit( so like a voltage multiplier but the capacitor is these capacitors). So I would have an output of 500 amperes(6 3000 farad capacitors in series would have a capacitance of 3000f/6=500f) and output voltage of 16.2 volts. For charging this power supply I will use a step down transformer connected to the mains with some circuit breaker, fuse, switch and ballast/ resistor at its input, the transformer will step it down to approximately 2 volts ac which then I will rectify with a bridge rectifier. 2. Putting them in parallel so I would have a total capacitance of 18,000 farad at 2.7 volts, and putting them in parallel with my power supply. So this works by charging the bank and the bank will discharge when fully charged. The power supply will be the same like the first design power supply. However this circuit seems very risky and I might need some feedbacks. For your information I live in Indonesia and the wall outlet have 220 volts with amperage of ~20 amperes So I have some questions which are: Q1. Which power supply design is more ideal in terms of safety and efficiency? And how can I improve? Q2. For power supply design 2, I believe I might need some "system" for timing the charge and discharge of the bank,what circuit or system should I use/ make? How about using relay? Or spark gap? Q3. What should I do to avoid explosion of capacitor in both power supply Q4. What components are recommended for the charging power supply and what diodes are recommended for the design one capacitor bank? I already have the thick wires necessary for this since i know both systems deliver huge amount of power. And please inform me if there is any mistake or anything wrong. Any input is very greatly appreciated, you don't meed to answer all question since i know is a lot and i don't want to waste anyone's precious time. Thank you so much for your time.

Question by dikap123    |  last reply


Noisy pot issues?

Hi, I've been experimenting with a variable output power supply. It takes 18V @ 2amps in from a wall adapter. It uses the LM2596 simple switcher as a regulator. My circuit is more or less the same as the test circuit from the datasheet (image attached). The only thing I've changed is that R1 is a 5k trimpot and R2 is a 50k 10-turn pot. The trimpot is so I can dial in the proper value for R1 and the other pot is to vary the output voltage. It works more or less as it should. The one issue I'm having is I think due to the inherent "noisiness" of potentiometers. When I turn the knob (sometimes it seems when I just touch it), the output voltage will "spike" up. It eventually falls back down to where it should be and stays steady, but it seems to spike everytime I adjust it. Does this indicate a bad pot? Or is there some additional filtering circuitry I can put to avoid these spikes or ripples? Would another L-C filter help? Thanks in advance,

Topic by deadbilly    |  last reply


circuit troubleshooting help

Hi- First on an unrelated note, does anyone besides me see "A fatal, non-recoverable error has occurred" over on the Makezine forums when you try to sign in? I've been getting that for weeks! Anyway... I'm working on a variable power supply that uses a 317 to regulate the 18 volts coming from a laptop switching supply. There are two 5k 10-turn (for precision) pots with a switch so that you can have two "preset" voltages and switch between the two of them at will. There's a single output. There's also a little lamp (I used a micro mini 12v lamp instead of an LED because that's what I had) that goes on above the pot that's currently switched in. The circuit I built (schematic is below) seems to work more or less fine. 'cept there's two strange issues: First, although the pots are linear (not sure if that would make the difference or not), they seem to "flatten out" toward their upper range. The first six turns gets you from 1.2 to about 16.5 volts. Then the last four turns either don't change anything or they do so in _very_ fine increments so that you only get from 16.5 to just over 17 volts. That's in four whole turns of the knob. This happens for both pots. The second stange thing is that turning the non-activated pot will affect the current voltage. When you increase the resistance (turn the knob to the right), the voltage level actually drops! Conversely, turning it to the left will increase the voltage. Remember, this is the switched-off pot. The switched-on pot works as it should (barring the mentioned weirdnesses). It looks like how much the voltage changes depends on how many turns you've given the activated pot. I suspect this has to do with me using a SPDT switch instead of a DPDT and maybe some voltage / current bleeding through the lamps and into the adjust pin, or something. But I ca/n't figure out why the switched-off pot would do anything. Anyway, take a look at the schematic. Is there anything I've done wrong that I'm missing? Should I, um, switch (*cough*) to a DPDT switch (something like the second schematic)? I used the SPDT cuz that's what I had. Anyy help is appreciated, Thanks!

Topic by deadbilly    |  last reply


My power supply wont work, whats wrong?

I have an old AWA power supply that puts out DC between 10 and 24 volts. i was running a motor at 24v and suddenly now stays at 24v. i turn the potentiometer and nothing changes the voltage. Whats wrong and how can i fix it?

Question by microbike    |  last reply


Powering a multimeter built into bench-top power supply?

Recently I built a bench-top power supply from an ATX power supply (Like the one from here: https://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe). It works great but I'm looking to consolidate this and my analog multimeter into one box. I'd like to know how to power the multimeter using the power supply so I don't have to worry about changing the batteries. The multimeter uses two AA batteries and a 9V, and the power supply has voltages of 12, 5, 3.3, 0, -5, and -12. Thanks for any help.

Question by ranab998    |  last reply


Could i use pwm to vary voltage for a benchtop power supply? Answered

I wanted to create a variable benchtop supply from a computer atx supply. Could i use a MOSFET with an arduino to vary the voltage coming from a 12v power supply? Initially i wanted to use a LM317 but since that would be inefficient. The mosfet in question is IRF540N Here is the circuit diagram

Question by qwerty156    |  last reply



Raspberry PI power?

Hey yall! I just recently bought a Raspberry Pi! Those of you who want to order know how hard this is, so Im pretty excited because i didnt think Id b able to order for awhile. Anywho, I wnat to make or buy a portable power supply for it, but I am not sure how to go about doing that. I know there are tons of portable CHARGERS out there for iphones and what not, but I am afriad these will attempt to "charge" my PI, therfore frying the board. Do they just supply power and the device recognizes power being recieved, so it displays charging? And I will be attachin a BUNCH of things via a usb hub to the Pi, so I doubt regular bunch of 4 rechargeable AAs will pwer my device for long with all thse extrra things drawing power. So my question is 3fold: can I buy one of those portable chargers to power my Pi or will it fry it? will 4 AAs be enough to power the Pi and all the extra usb things? and will it be more cost efficient to make a power supply? (I definetely want it be rechargeable, though). Any links to products, or guides to make one would be extremely helpful. Thanks in advance!!! Also, I already have a wall supply, but I need a power supply that is portable.

Question by Adum24    |  last reply


Are high power resistors really neccessary on a benchtop PSU conversion?

Was looking through the site and I was just wondering--why all the huge resistors on the bench-top power supply conversions of PC Power supplies? From personal experience this seems like a waste of perfectly good electricity.I know that they require some current to just stay on however in designing a project for my school's Engineering Technology department I found that the heat generated by such a small resistance (Around 10 ohms) was unacceptably high. Originally I was looking at Instructables and this sitethis site for inspiration but all the cooling measures taken to prevent the high power resistor from becoming a hazard seemed rather silly. A few calculations and experiments later with the 250 watt power supply and I determined that 160 ohm1 watt resistors and 1K 1/2 watt resistors were perfectly acceptable for the purpose of keeping the PSU awake and functioning. I connected one of each between each voltage and ground. According to calculations I can get away with dissipating a grand total of two watts or less spread across multiple resistors.The current divider rule dictates that if you add resistances in parallel, the resulting resistance will be smaller meaning more current will flow through the overall circuit. However this increased current will divide itself across the parallel resistances according to the rule Ix= RtIT/(Rx+Rt). The current through and power dissipated by the resistor you've soldered into the PSU will not change enough to be significant no matter how large or small a resistance you attach in parallel with it--with the exception of an effective short and what in God's name are you doing intentionally shorting the terminals of your bench-top PSU? Now several months later, the PSU is still operating happily and powering multiple micro-controller projects on a display board. Therefore I can reliably conclude that the high-power 10 ohm resistors in many computer power supply conversions are probably a gratuitous waste of wattage. You can get away with using a higher resistance and a resistor that dissipates much less current.

Topic by Psickattus    |  last reply


can anyone tell me what is wrong with this circuit? Answered

I keep on burning my 555 each time. checked the circuit intallations more than ten times. voltage using is 12v from a car battery.  however i am using irfp 450. i don't think that this is a problem. my ammeter say 5 amps of current passing but no ark to the transformer. first i thought that the transformer was not good. so i changed it. problem was still not solved.  then i thought that the winding was not goof. i rewound it but no success. the mosfet just get hot.  so i think i will bring my driver to school monday so that i can know if the circuit works. i removed the mosfet and put a led instead i also change to capacitor with a 10uf cap. the led blinks. therefore the problem is not with the circuit if the led blink. what can the problem be. i used different kind of mosfets also. still not getting the arcs. 

Question by ARJOON    |  last reply


HV power supply and ZVS switching? Answered

I am slightly running out of brain power here and get the feeling I am just running around in circles. Problem: I want to build a HV power supply delivering 10-15KV that is driven by a ZVS circuit - basically the same I used in my Induction Heating Ible. I also want to double the output voltage with a simple cascade. Goal: To get the most effiency without overheating things. Areas where my brain feels too empty from thinking: 1. I know for sure the primary of the transformer will operate at a resonant frequency but how does this affect the scendary coil, especially under load? My small scale tests showed quite severe changes in the frequency depending on the load put onto the primary... Also the output voltage shows "spikes" at certain frequencies, I assume this happens while both primary and secondary share some harmonic frequencies. 2. With a simple dide/capacitor cascade I would only get a DC output, to keep an AC output slightly more complex circuits are required. How does this affect the resonant frequency of the secondary winding? 3. Considering 1 and 2, is there a simple way of keeping both the primary and the secondary coil of the transformer in resonance regardless of the load?

Question by Downunder35m    |  last reply


High efficiency coilgun design

Hello there I need some (a lot of) help with my project. I've started to design a high efficiency multistage coilgun. The main feature of the design is using the self-inductance formed in coils that were shut down for accelerating the following coils. To perform this, we can divide each coil into 3 segments (lets call them subcoils), connected with a wire and power all them 3 with a single capacitor. At first, the current from the capacitor is flowing through all 3 segments and a projectile is being pushed through the first segment. Than the first sensor is being activated with the projectile and it switches the power flow to only second and third subcolis As the current in the first subcoil is changed, the self-inductance directed in the opposite direction is appearing. In theory, we can use this power to increase the current in the following segments. The same thing is happening between second and third segments. And I want to place 3 of this stages (9 subcoils in total) I will use 8mm caliber projectiles, 40mm or 50mm length. I chose 5200mkF 450V or 6800mkF 400V capacitors, 2 of them in parallel for every stage (6 capacitors in total) Yes, I know it sounds way too powerful, but that's my actual goal. It's not my own idea. I have learned it from here http://gauss2k.narod.ru/adf/gs3seg.htm (русские вперёд). So, some problems had appeared. I can't figure out how to properly calculate the required inductance of the coils. In the source it is said that the inductance of the first subcoil should be equal to two of the second and the third subcoils (L1=2*L2=2*L3) to achieve the best performance. Also, my rough estimates show that peak current through the coil will be about 1,5-2,0kA for 3,0-4,5ms. This is quite a lot! I'll have to manage this energy and choose the power switches rightly. To sum up, I will be glad to hear your opinions about this idea. It's kind of controversial, but I hope it's not a certain failure.

Topic by CosmoKnight    |  last reply


Can I put Color-changing multi-color RGB LEDs in series??

I need to run a bunch of slow-changing multicolor off of 12vdc.  The LEDs are each rated 2.5-3.4V 20ma.  I'd like to keep efficiency up by reducing the number of series current-limiting resistors and the voltage across them.  So...  Can you put 3 multi-colored LEDs in series with a current limiting resistor (typ 150 ohms) to run off 12vdc... like you do with standard LEDs?  The datasheet specs a operating voltage range and 20ma current. Or...  Does the current draw (effective resistance) of the LED change as the colors change??... Example: When displaying purple, red & blue are both lit. But for red, only the 1 internal LED is lit. If the current changes and the different LEDs are out of time, it would change the voltage across the different LEDs and the series resistor. (I know you can't run an on-off flashing LED off a higher-than-spec'ed voltage because the current goes between almost 0ma and 20ma, putting nearly the full supply voltage across the LED when it is OFF.) So, can I put them in series successfully?? Also, how accurate is the color-changing timebase?   Will they quickly go out of sync.. assuming the same brand and lot.

Question by BarryS78    |  last reply


How to vary output of DC power supply?

I have a DC Power Supply, Model 20R, 120 input, 13.5 DC output, 20 amp.  Is there a way to change the output Amps?  I want to use this power supply for nickel plating. I need the amps to be variable or fixed at more than the onr setting of 20 amps.  (example 2, 4, 6, 8, 10 amps ) This is a nice heavy duty PS made in USA.  A new DC PS is over $400 and they are cheaply made imports. I used to repair electronics for NASA years ago.  I most likely would have known how to do this back then, but the older I get the more I can't recall. (Old age is not fun!!) My point is, I have the experience to do what you tell me to do. Thanks

Question by Old_Chipper    |  last reply


Power Inverter or DSO Problem?

Recently bought 2000w power board to play around.  Sets DSO at 5mS/Div. The output frequency change intervally between 40Hz and 50Hz. Sets DSO at 10mS/Div. The output frequency stable at 50Hz. Please advice which once is the problem? Update June 1, 2017 1. ...do you have a load on the power supply ? With or without load, same results. 2. Try changing the scopes trigger level.. Getting same resulted too when changes the trigger level.  3. Measures with multimeter. Get 49.98Hz and this is normal. 

Question by GearUp    |  last reply


Arduino Multimeter on 1602LCD? Answered

Hi I am currently in the process of finishing the code for my Arduino controlled PSU with an LCD volt and amp meter. My question was basically, how can I get the volts and the amps to show on the LCD with 3 decimal place digits instead of 2 which i have now. Also, im having trouble putting 4 measurements all on one display- i currently have watts, amps and volts but i wanted to add resistance, however, for some reason i cant fit them all in one screen and i get weird errors when i try changing the setCursor value.  Thanks P.s here is the code I'm using (a took bits off different websites and examples-will reference them in the final sketch) #include const int numRows = 2; const int numCols = 16; LiquidCrystal lcd(12, 11, 5, 4, 3, 2); int analogInputVolts = A0; //voltinput int analogInputAmps = A1; //ampinput float vout = 0.00; float vin = 0.00; float amps = 0.00; float watts = 0.00; float ohms = 0.00; float VA = 4.970;          // Arduino 5V supply float R1 = 2995;        //  R1 in ohms float R2 = 999;        //  R2 in ohms int readAmpsADC = 0; int readVoltsADC = 0; void setup(){   Serial.begin(9600);   lcd.begin(16, 2);    pinMode(analogInputVolts, INPUT);    pinMode(analogInputAmps, INPUT);    delay(500);                    } float fmap(float x, float in_min, float in_max, float out_min, float out_max) {   return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min; } void loop() {    readVoltsADC = analogRead(analogInputVolts);    readVoltsADC = readVoltsADC + analogRead(analogInputVolts);    readVoltsADC = readVoltsADC / 2;    vout = (readVoltsADC * VA) / 1023.0;    vin = vout / (R2/(R1+R2));     delay(100);         readAmpsADC = analogRead(analogInputAmps);    readAmpsADC = readAmpsADC + analogRead(analogInputAmps);    readAmpsADC = readAmpsADC + analogRead(analogInputAmps);    readAmpsADC = readAmpsADC / 3 ;      // get average of 3 readings    amps = fabs(fmap(readAmpsADC, 509.0, 699.0, 0.0, 5.0));    if (amps < 0.09) amps = 0.00;    if (amps > 5) digitalWrite(13, HIGH);    delay(100);    if (vin < 0.5) vin = 0.00;          watts = vin* amps;    ohms = vin / amps;    Serial.print("Resistance-Ohms:");    Serial.println(ohms);    if (amps = 0.00) Serial.println("Nil");          lcd.print(" ");    lcd.print("V:");    lcd.print(vin);    lcd.setCursor(1, 1);     lcd.print("A:");    lcd.print(amps);   lcd.setCursor(0, 0);      lcd.print(" ");    lcd.print("W:");    lcd.print(watts);    lcd.setCursor(7,0);       delay(400); }

Question by lightemmitingdiode    |  last reply


How to get 9 volt from a computer power supply? Answered

To save some energy i thought it would make sense to remove all those small powersupplys. They all transform pricey power (24 eurocents per kw/h here) into heat. However, in my computer is a powersupply that actually is very efficient, also, if i take more energy from it, it wouldn't have much more loss. Right now my computer uses about 54 watts if idle (i selected the components to be as efficient as possible). My DSL-Router uses 14 watts, but i guess most of it goes away as heat in it's own little PSU. The DSL-Router needs 12 volt and my computers PSU can deliver that, and since the DSL-Router is only needed when the computer is switched on i plan to use the computers PSU to power it. I have a pair of speakers with an internal PSU and AMP. After opening them i saw that both are on separated boards. The PSU gives 9 volt to the AMP and gets quite hot while doing it. The problem: as far as i know there is no 9 volt power connection in the computers PSU :(.

Question by tecneeq    |  last reply


Wearable 5 V 9 A power supply? Answered

So I am making an electronic t-shirt with a very bright screen that gobbles up amps. At it's probable peak usage it will be using 9 amps (or 8.697, but I always feel safer sizable margin of error). Luckily this will only be at its peak for a few seconds (at most 10 seconds, probably less) when it starts up. Next it will use  between 4.5 to 3 amps continuously, and later will  be using closer to 1 amp. All of this is at 5 volts, and I will be stepping down from 7.4 volts. As if this wasn't hard enough this is battery powered, so good efficiency would be nice. I want to minimize the amount of power lost. Is there a power supply that can do all this and still be wearable? In short, I need a wearable 5 volt power supply that can provide a few seconds of 9 amps and 4.5 amps continuously.  Thanks! Edit: Thanks Everybody! For people who find this in the future, here’s from saving you from having to read through all the posts… In the end I found the answer to my problems was cutting the peak amps it needed to consume it half, bringing it down to around 5 amps. What I ended up choosing was the R-745.0P power supply. Look at the last page of the datasheet for clarification on how to wire it, and when it comes. The mpilchfamily thread talks about safety, which is important and worth reading if you want to know about it. I wasn't sure on whether or not I should go with the R-745.0P and all the supporting components or the UBEC 2-5S, which is an all in one package. I chose the R-745.0P but it’s up to you!

Question by GenAap    |  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


Can Anyone tell me how to simulate the current changes in LM723 in Proteus?

So I'm making a circuit of power supply with LM723 (Proteus File and schematic attached below). Can Anyone tell me how to simulate the current changes in Proteus.

Question by mnaveed    |  last reply


Power banks and solar cells -could be great Instructable for you to make!

I was lucky to score a nice and real 8000mAh power pack with a solar cell from my local discounter.Realising the solar cell is more a gimmick than of real use I started to wonder....We all love our mobile devices and really hate that they need to be constantly charged up again.On long outdoor trips people used to carry a lot of gear and vital supplies.In todays times it almost seems that solar and battery power start to replace food and water.No trip is complete without pics, selfies and videos, some even take a drone with them.So: are there ways to increase your luggage weight by thinking smarter?Modern technology has come a long way and moves faster ever year.Solar cells are no exception here.Be it foldable setups or now even roll ups of flexible cell systems, you have the total freedom of coice.But then again: You are going on a week long camping trip in the middle of nowhere...Going on foot or using a bike means you need to keep the extras down or hire someone to carry them.Here are some of my yet to be finnished ideas:As long as you don't use them commercially feel free to make an Instructable or just use the ideas!1. Pop up amd normal tents.They seem to be the new standard now.Big with no poles on the inside and even someone who never used a tent can set them up.With the design comes a certain way of folding everything to pack it.Flexible solar cell designs won't break and can often be arranged so they would actually be able to replace parts of the outer tent material.And if it could mean they would get kinked too much and too often they are still perfect to create some "strap on panels" that can be rolled up and included with your foam underlay or mattress.A 200 or even 400W system can be transported easy and has less weight than a 80W fold up solution that you struggle to secure on your backpack or bike.2. Trackers!What is now almost a standard for fixed installations is still not seen in mobile setups.You pop up your panels, connect the power packs or batteries and go fishing, hiking or whatever.The sun moves on, the efficiency of the panels suffer.There are a lot of great Ibles for these solar trackers, from simple to 3 dimensional.Kites loves to use carbon fibre rods to reduce the weight.A tracking frame to hold a good sized flexible panel would count at less than 300 grams....In return you get up to 40% higher effiency and overall output compared to a fixed panel!Roll the panel up, fold the frame and you end up with a quite small roll that is easy to transport and very low in weight.3. Battery backups.No matter how long and well you planned, the weather might let you down shortly after your trip started.For a lot of comitted people that is no problem.The lack of power though can cause some to struggle to keep their video logs running.Your small drone might be great but it only lasts for less then 30 minutes until you need fresh batteries.Similar story if you use stabilizers, automatic tilt and pan gadgets or just a 360° camera.Just your cell phone alone can be a hassle if you use it as the main thing for GPS, pics and videos.At least one set of spare batteries seems to be a must have these days.For a lot of things it does make sense, for others not so much.Unless you really need ongoing power it might be enough to just charge you empty battery at the end of the day.But then the sun is down and options are gone for solar energy.In the RC area we can find a lot of powerful battery packs.Usually around 14V but 40 or more are no problem.And if you check the E-bike and scooter sections you will find some quite powerful and light weight battery packs.If you go outdoors a lot and for longer periods of time then it makes sense to replace the multiple battery options with just a single one.Use a high power backup battery with your solar system.DC-DC converters make it possible to literally combine everything with everything.Select the battery size so it will suit your charging needs and capabiliteis of the solar setup.Once time to close the tent you enjoy electricity to finnish your logs while your batteries are being charged during the night from the backup.4. Emergency generator.We all know these cheap gadgets like crank up torches or cranking mobile phone chargers.Nice to play with, utterly useless if you actually have to rely on them.A full charge for your modern phone might mean you crank for at least half the day - good luck!If you already carry a supply of gas for your cooking needs then these new fuel cells running on butane might be nice.Some of the Kickstarter projects actually made it into production!Prices though are more for real fans or those with enough money...But a small RC engine can drive some nice DC motor with very little fuel....In return you get a pocket sized generator that can charger your phone fully in the same amount of time a wall charger would...

Topic by Downunder35m  


Can I run 10w 12v leds directly form a switching power supply? Answered

Hi, I have a regulated switching power supply with 12vdc 400w output (similar item pictured below) and I need to power around 20 10W LEDs which are rated at 900mA. Can I wire these in parallel directly from my power supply since I know the voltage can't change meaning that the current (and heat) shouldn't really change? Thanks in advance.

Question by reducingmyconsumption    |  last reply


I need to power 12V LED strips off of 6AA batteries that produce 9V. How can I get the extra 3V?

I plan on putting LEDs under the keys of both my Yamaha and Casio keyboards, The LEDs must me on strips so they dont interfear with the instruments playability. I have only been able to find LED strips that run on 12V and I dont want to have to add a second power source. How can I either change the resistance values on the LED strips or change the input voltage with out adding a new power supply?

Question by fastcar123    |  last reply


Different collor high powered 3 watt led strings on one constant current power supply? Answered

Greets, Can i connect 3 different collored led strings to one constant current power supply? This is my power source, gives min 9v and a max of 48v @ 700mA Mean Well LPC-35-700 https://www.meanwell-web.com/product_info.php/products_id/LPC-35-700 My leds all 3 watt 6 x 630nm red - 2.5v/3v - 750mA 2 x 660nm deep red - 2.2v - 700mA 2 x 460nm blue - 3.4/4v - 750mA Can i create these string? 1 string with 6 x 630nm = 18v @ 700mA, should have no problem to run, right? 1 string with 2 x 660nm = 4.4v  (9v min from power) 9v - 4.4v = 4.6v / 0.7mA= 6.57 ohm resistor i should add to this string, correct? 1 string with 2 x 460nm = 6.8v (9v min from power) 9v - 6.8v = 2.2v / 0.7mA = 3.14ohm resistor i should add to this string, correct? Can my power supply handle this? Since it changes voltage. If i can use this, which watt resistors would i need? I would also for example like to add 1 potentiometer for the 460nm blue leds And add 1 potentiometer for the 660nm deep red leds Am i asking to much here or can this be done? Thnx JB

Question by MistaMasta    |  last reply


Will this 'switching' circuit work for cabinet lights? Any comments?

Im making cabinet lights using LEDs. I use a transformer to power it off AC mains, but I want it to run on batteries too... So Im making a circuit that would automatically change the source of the power from the mains to battery when the power goes out, and back again when it comes on. Im using an NPN and a PNP transistor to do the switching. When mains (S1) is on, the NPN is on and current flows from the transformer, when S1 is off, NPN is off and PNP is on and current flows from the batteries. What I am worried about is that (I think) the transistors need a Gnd on the emitter. Is that right? If I connect the +ve of LEDs to [OUT] and -ve to GND will it work as expected? Can someone try please?

Question by pro2xy    |  last reply


Can an induction heater for domestic use (2000W) of 220V/60Hz be used efficiently with 230V/50Hz power supply?

I purchased one Induction heater (2KW) in Korea where the supply voltage is 220V/50Hz. I want to use this in India where the supply voltage is 230V/50Hz. Can this be used? 

Question by Eappen    |  last reply


How do I wire a car power door lock actuator to a 12V power supply?

Looking for some advice on wiring a car power door lock actuator and remote central locking keyless entry system to a 12volt power adapter. We've got a chicken coop that I would like to connect the actuator to so we can open the latch from inside the house. The items we have are a CfD Universal Car Power Door Lock Actuator 12-Volt Motor & a Docooler® Car Remote Central Lock Locking Keyless Entry System with Remote Controllers. The Remote has 10 wires coming from its harness. I know enough about electrical wiring to efficiently burn the house to the ground. Figured I would post a question here before that happens or I destroy the thing. Any advice would be GREATLY appreciated! Thanks

Question by LarryIannacone    |  last reply


Inductive coupling with/and AC? Answered

Several things I wanted to know, but couldn't find; If 2 AC outputs are of the same amplitude, but of different frequency, will one necessarily be higher in power? In a conventional transformer, (not resonant) does a higher frequency allow for higher efficiency coupling? Does this change if the transformer is resonant? Is a 'standard' transformer more efficient than a resonant one at a very close range? (Provided that frequency, power, etc. are all the same?) And lastly, does the resonant frequency of a resonant inductive coupling circuit affect the frequency at which it couples? (did that all make sense?)                                                                                                                                        Thanks

Question by .Unknown.    |  last reply


How much power, amps, and voltage would a Panasonic plasma's USB port supply and would it run a computer fan?

I would like to run two small computer tower fans off of the two USB ports on a Panasonic TCP50ST30 plasma TV. I am planning on recessing the tv into the wall so it is not visible from the side and I was going to use the two fans mounted in the wall directly behind the television to draw the heat the tv makes out of the cavity. Is this possible? Each fan uses 1.32 W at 0.11 A with a voltage range of 4- 13 VDC. If not is there any other cost efficient suggestions.

Question by Bubba1648    |  last reply


Is it possible my mother board or power supply is bad or dying?

I have a computer that was having a lot of problems so I tried to reinstall windows XP.  Due to several problems I pulled the HD and installed it in a external case and formatted the drive and reinstalled it.  tried to load windows again but it took over a day for the files to copy over.  I thought it was a bad HD so I put in a new HD and had the same problem. However once it was installed the video resolution could not be adjusted.  I thought this was a problem with my reinstall disk so I overwrote everything with Ubuntu and had the same slow loading.  Now Ubuntu starts to load but then it takes a very long time to boot and then everything moves slowly (for example I move the mouse and about 15 seconds later the screen registers the change).  any ideas as to what is happening?

Question by shantinath1000    |  last reply


How can I get a suitable voltage from a 5V power supply? Answered

Hi all, I've got a laser diode, with the following specifications: "Wavelength:808nm Power Output CW 500mW Working Current: I<350mA Working Voltage: 2.2V" And a laser diode driver: "1. Constant current Stable voltage IC circuit, laser diode can be better protected without being damaged 2.Constant current output , Can be adjusted(0~580mA) 3.DC supply voltage input 3.0~4.2V. 4.Suitable for 808nm 100mw~500mW laser diode." The combination of these two things will be switched on and off by an Arduino (Probably using a relay, as the driver board has a switch connection) - This may change but I don't imagine this will matter. ---------------- I noticed that the 'DC supply voltage input' says 3.0-4.2V . My power supply will be 5V (I don't imagine that Amps matter but if they do, it has a max output of 34A). What would the best/safest way to do this be? I don't want to burn out my laser because they're comparatively expensive, and I'd like it to be able to run relatively continuously (Probably multiple-minute continuous usage) (For those of you wondering, I'm one of the many people making a laser engraver/cutter from scratch)

Question by jonrb    |  last reply


Get rid of batteries on the Fisher-price swing to DC input

We bought a new swing recently and has been consuming 4 C batteries every week. I am wondering if can hook it up to Wall transformer. Any ideas? I have some wall-wart at home that output 6-9v. Can I use them? I can convert the wall-warts as per the instructions here: https://www.instructables.com/id/wall-transformer-for-project-power-supply/ but do i need to change anything in the swing? and how to hook it up?Please advice ..Thanks

Topic by sulakhe    |  last reply


Can a arduino pin mode be changed mid program?

Hi, I'm working on a project that requires a reading to be taken from a pin (digital) and then that pin needs to be supplying power. Can I change the pinmode from input to output mid program, or do I need transistors to switch it between different pins instead?

Question by David97    |  last reply


How to test N channel mosfets? Answered

Hello, i built a ZVS driver about an year ago. I used to power it from a computer power supply at 12v ,than i changed the power supply to 30v and 10a.With the new power supply it worked as well for about 3 moths. A week ago a wire got burnt and a zenner diode. I wanted to test the mosfets too but he tests i searched on google didnt work. Please tell me a good method to see if my mosfets are burnt or not .

Question by theVader75    |  last reply


Led downlight transformer converting to a battery charger/power supply?

I know everyone will just say make the Ible and be done with it, but... I got a bunch of 11.5V LED downlight transformers, 35-105W. Upon inspection I realised their design is dirt simple but quite effective. Switchmode for the beginners so to say LOL The pros: Changing the output voltage is as simple as adding or removing windings from the output transformer. In my first test I was able to go up to 20V with no problems by adding a few turns and down to 5V by replacing the secondary with far less but thicker windings - impressive 12A until my windings started to produce smoke LOL Only imple parts, no microcontroller or other complicated stuff like opto couplers... The big con: These transformers are about 20 years old, so I would say first or second generation of LED transformers. That means I have no clue if something very similar or even identical can still be bought in shops or online. And what is the point of an Ible that noone can do because the main ingredient is nowhere to be found? I can take some pics of the circuit board later on for comparison but it would be great if some people with LED downlight transformers could provide some pics too. If it turns out other transformers are still in the same simple design I would like to use all provided for an Instructable. Credits for the pics will be left if you want or simply add your username to the pic as a watermark or such.

Question by Downunder35m    |  last reply


How do i change a 18v 1.5A DC cordless drill battery to AC? (in other words, how do i change dc to ac ?)

I need a high voltage power supply to power a tesla coil from a battery, and i need ac not dc, so if i can change my battery to ac then i can run it through transformers to get HV AC power to run my tesla coil.

Question by lightning r fun    |  last reply


Higher efficiency (high amp) 12V regulator alternative to 7812

I need a high efficiency 12V DC regulator to supply my thermoelectric modules (they're very inexpensive so I had no choice but to use them). I found that the modules are most efficient at 12V @ ~7A each. I could use many 7812s in parallel but they are too inefficient and too much energy is lost to heat. Is there any alternative? Electricity bills are going up so it'd be very good if I can find an extremely efficient step-down or step-up regulator, short of using an expensive 'gold standard' ATX PSU (which are usually upwards of 500W so the power savings don't matter).

Topic by arikyeo    |  last reply


How do I wire a LTC3780 to my arduino and display?

I'm re-purposing an old ATX psu into a variable bench psu. The current project has LM2956's however they're faulty, I can only see 11.78V max instead of 29+V. The other down side to these modules is the lack of current control. The project also has an arduino Mega handling acs712 hall current effect sensors and Voltage dividers for my 3.3v 5v 12v terminals and two LDC dispays 16x2 and 16x4. So I was wondering assuming I keep the basic design of the psu can i replace the LM2956s for a single LTC3780, How can I wire the LTC3780 to the arduino and allow me to see the current change.  Thanx in advance.

Question by icey.hood    |  last reply


Desktop PC DC - DC UPS ?

This might sound stupid, but I was watching some guys build batteries to Electrical Cars using Laptop batteries like Tesla does (18650 battery Cells)  and I got thinking about creating an UPS for my PC. If Im not mistaken, most UPS convert AC to DC current and in a mains power loss they convert back DC to AC which is not very efficient I assume. So why not instead of going thru that process, why not power the PC components directly from the UPS in the event of a power loss or power supply failure?? My idea was to build a UPS that works completely on DC power, from its input to its output. So the PC power supply would charge it and the UPS would power the PC components in case of a power failure. I would be using this on a server so I dont need monitors or other stuff. All that would be require would be power regulators for 12V, 5V and 3.3V right? Wouldn't that be more efficient? (the battery would last longer due to less power loss on conversions I think)  And wouldn't it be cheaper?  Thanks, Ralms

Question by RicardoM146    |  last reply


Reusing desktop and laptop monitor CCFLs and power supplies to make a floodlight

I'm using a collection of broken laptop and desktop monitors I got free from a repair workshop to assemble a floodlight/spotlight from the CCFLs and their inverters. The desktop monitor power supplies take mains voltage (240 V) and power the CCFLs but also seem to provide a 5 V and 12 V supply to the electronics that control the LCD. The laptop inverters themselves accept either 5 V in some cases or 12 V in others so naturally I want to run the laptop inverters off the 12 V and 5 V supply because otherwise it's wasted. The problem is that I don't know how much power I can draw from the 5 V and 12 V of the power supply. I've had a look at the back of a monitor that says it draws 0.7 A at 240 V. What translates to 168 W which is more than I was expecting. Assuming that the four built-in CCFLs use 8 W each, that would still leave 136 W. Assuming the power supply is only 60% efficient that leaves (168 W x 60%) - (4 x 8 W) = ~68 W. I've no way to tell how that's distributed across the 12 V and 5 V but if it's 34 W each then I can draw 2.8 A from 12 V and 6.8 A from 5 V? I figure I can probably, maybe attach eight laptop inverters to each desktop PSU (four on 12 V (1.6 A) and four on 5 V (4 A)?

Topic by THX 1138  


Can I have flowing liquid through multiple separated electrolysis cells, with those cells in series? Answered

Hi, my question is a curious one regarding electrochemistry. I have multiple electrolysis cells, with some separation between them but a constant flow of water passing through each of them in turn. Since electrolysis cells like this tend to require a current-limited power source and don't end up dropping much voltage per cell, I wanted to electrically connect the cells in series. This way, I could use a single power supply in current-control mode and not have multiple supplies fighting each other. My assumption that individual power supplies would end up fighting each other is based on the fact that the water is an additional electrical path that can allow current to bypass a given electrode. Using one power supply and having the cells in parallel would not be a problem as long as the current through each cell balances out on its own, however I feel that having one power supply across all cells in series would make current balance per cell a non-issue. My question is: Is it true that, with a power supply pushing a single current through multiple water electrolysis cells that have a torturous but admittedly connected water path, electrolysis efficiency will be the same as having separate power supplies on each cell?

Question by DavidB568    |  last reply


PSU design (major revisions): Transformer calculations help?

Recently I have attempting to design a proper dual-rail power supply that will allow me to set a voltage as low as +-1V up to +-30V in 0.1V increments at (hopefully) 3 significant digits (at least for the lower voltage settings). Anyway, this supply is also going to be current limited to up to 5A,again, it can be set to just about anything. I plan on using an Arduino micro-controller to set the output. In order to do this, I plan on using the analogWrite functions, or better yet, a legit DAC. There will be 4 outputs from the Arduino that will set the power supply output by applying a 0-5V voltage on the input of the 2 current limits and 2 voltage sets. (one for the negative rail, one for the positive). However, I have kept running into the same problem: how do I plan on driving this linear power supply with up to 200W*? My first idea was to use a a MOT, due to their high-power capabilities, and re wind the secondary with the right number of turns to achieve this output. However, I have heard that these transformers are not optimal for continuous running due to their poor and cheap design. (losses are very high). My second idea was to search around for a 250VA transformer. However, even until now, the VA rating confuses me. How does VA compare to W? I know this has something to due with reactive power, real power, and apparent power. However, I have no intuition of any of these 'powers.' How would I go about calculating the correct size transformer for the job, also, I am going to assume this linear power supply has the properties of a resistive load, since it is rectified and smoothed with a filter capacitor, so practically nothing should react with the AC power. (unless there is something more to the full-bridge rectifier setup I am considering.) This is when I came across unwound toroidal cores found on eBay for $25, the perfect price range! However, this has raised more questions! to start off, beyond turns ratio, I do not know now many turns I need for the AC side of things. I know intuitively and from experience, mains-frequency transformers do not work with only one (or even few) winding(s). I think this has to do with saturation, but I'm no expert by any means. and the inductive reactance of the transformer's primary. How do I calculate losses, inductance, and other important parameters of a homemade transformer like this? Things get very nasty when I look back at rewinding an old transformer. Now I have all these questions about inductive reactance, power, currents, magnetic flux and saturation, but also, about determining the original power rating of something like a very old small welding transformer or one from a large 10A car-battery charger. Is it possible to approximate the power by measuring the dimensions of the core? How close will this approximation be?  After getting frustrated with this, I considered alternative approaches. What if I purchased 2 ~20V ~6A SMPS (switch mode power supplies) connected them in series, and connect the center tap of my linear supply to the joining point between the 2 SWPS's? Would this be unstable and be bad for the SMPS if a load was connected between the 'outputs' of this new center tapped supply? Would any sort of balancing be required? Also, a bigger problem includes how this will be connected to my linear PSU design. With a low voltage @ high currents, I would be wasting a LOT of power, power that has to be dissipated away from the transistors. This heat can approach 200W, which is company unreasonable! Anyway, I would them have to either a switching preregulator, or modify the SMPS's so the voltage can be controlled easily and varied between, say, 3V to 20V. absolute accuracy is not required, close enough, and rest of my PSU should handle it. This becomes seemingly impractical too, and many other considerations need to be made. What should I do? what are the calculations and factors I need to know? i do not have an LCR meter to measure inductance, so trial and error is out. Does anyone here have experience at this? Help would be greatly appreciated! *The 200W figure was calculated by taking 40V, (What I believe would be a safe to allow some slack for +-5V voltage drop across my 2 shunts and transistors) and multiplying it to 5A of current for the maximum power output. ------------------------------------------------------------------------------------------------------------------- I have added an image of my current design, and I have modularized it the best I could. The YELLOW is all my current power-management circuitry. Currently just a transformer with many taps, going to a currently-undesigned switch box that will change the voltage on the output, which is then rectified and enters a filtering capacitor, finally entering the circuit.  The GREEN field is the voltage set. It is the most major part of the PID feedback loop, along with the ORANGE field. It works simply by feeding a voltage to the positive of a op amp configured as a comparator, and with negative feedback from the output. It then outputs a signal to the transistor, turning it either more ON, or more OFF depending on how the output voltage compares to the +Vset. The negative portion is largely the same, but the input voltage needs to be inverted so the output voltage is set negative properly. I was not able to use less than 2 op amps for this portion, unfortunately. The ORANGE field is current set. It works by measuring the voltage drop across the shunt resistor, and outputting a unity voltage that is referenced to ground, instead of to the positive rail. (It took me forever to finalize and perfect that!!!) Anyway, this voltage is then fed into a op-amp configured as a comparator to drive the transistor. The BLUE field is my switching regulation topology, which is controlled by both the ORANGE and GREEN fields. Do you like my use of diodes as a super-simple voltage or current selection switch? the op amp that outputs a lower voltage is the one that gets 'listened to' by the transistors. This way, current and voltage mode enable properly. This does add a small problem when it comes to powering the op amps, all of them have to be powered off of slightly higher voltages to swing the full range due to the voltage drops of those diodes. In the PINK field is simply a single-transistor solution to a constant current load. This allows the regulator to be regulated even at very low voltage set levels. This is why I am able to achieve a +-0.5V on the output (at least within LTspice) Finally, and most unimportantly, the light PURPLE fields have a simple ultra high-gain difference amplifiers that will detect if the output current and current set are the same, and turn On or OFF the respective LEDs. The green LEDs are voltage-mode indicators, and the red LEDs are to show when current-limiting mode comes on.

Question by -max-    |  last reply


High Power RGB Led Project

I will be doing my first high power RGB Led project soon based on these leds: http://www.ebay.com/itm/380364867527?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649#ht_2814wt_1163 I will be using it in my boat utilizing this RGB controller: https://www.instructables.com/id/LED-Rainbow-RGB-LED-PWM-Controller-Construction-/ I will be using the project in my boat and thus tied to 12v dc battery power bus.  The RGB specs call for: DC Forward Voltage (VF):Red 7.5V;Green 10V ~ 12V;Blue 10V ~ 12V @ 350ma per channel. My question is 'What is the best way to get the voltage down to the 7.5v required for Red'?  As I am in a boat with a single 12v battery, I would like to be as efficient as possible.  I plan to use 4-6 of these leds.  Since each requires 12vish on the highest channel, I am planning to put them in parallel. Thanks in advance!

Question by BigSicilian    |  last reply