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Picture of Simplest Ever DC-DC Boost 12v to 73v
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A simple DC-DC boost converter:
- 12-18v in = ~73v+ out
- Uses only 2 transistors, no IC's
- Can be made out of one CFL light bulb
- Uses fully discreet components
- 17.2kHz switching frequency

Output is only low current but could probably be used to power a small triode preamp stage (Very high impedance)

UPDATE: Thanks to "neumanngregor" for pointed out: ONLY USE ELECTROLYTIC CAPACITORS IN SERIES AS A LAST RESORT, I am not responsible to any damage caused. If possible, use properly voltage rated capacitors. Thanks :)

If you are unsure of the the inductor size, just try tweaking the oscillation capacitor until you get the highest voltage :)*

*A general rule, since this is a constant duty cycle, larger inductors will need a lower oscillation speed.

 
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Step 1: Parts and Specs

Picture of Parts and Specs
This is a very simple 4 component oscillator made from very cheap and easy to access components. It works through the breakdown of the transistor, as the capacitor charges, it gets to a certain voltage then the transistor conducts from the emitter to the collector. This process causes the capacitor to discharge through the transistors emitter, creating a crude sawtooth wave.

Most standard transistors should be able to cause an avalanche on 12v but some transistors dont (as I have found out!) I find the BC337 and BC547 to breakdown perfectly.

The circuit oscillates at ~17.2kHz, nearly above the audible range.

The parts required:
TIP122 or Power Darlington transistor
BC337 or Compatible
0.1uF/100nF Ceramic Capacitor
100uF Electrolytic Capacitor (Preferable 16v if the circuit is ran on 12v but 10v should do fine)
1k resistor
Any high voltage capacitor. I used two 63v capacitors in series to double the voltage rating.
Any suitable diode with high enough voltage (1N4001 isn't high enough voltage, its rated at 50v)
An inductor with inductance between 1-5mH should be fine

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shaileshi5 days ago

Hi ,

Can you help me to design converter for 24 v100AH battery. It converts into 51v, 350-400mA...

amitk2114 days ago

can this work to convert a 1mV to around 1-2 V?

GeorgeD516 days ago

Hi,

I can´t find the inductor (1-5mH), can anyone recommend any in ebay? or a part number to look for some? thanks :D

pyrohaz (author)  GeorgeD516 days ago

Hey! I wouldn't really recommend purchasing parts for this boost converter, its a pretty poor one if you actually want to put the effort into making! You can however find inductors in that range on eBay if you're in the UK:
http://goo.gl/WMoERb

There is an example of one source!

Hi,

How can I make (60 -100v) to (360 - 600v) ?

pyrohaz (author)  tarek.zekaroui16 days ago

That's a pretty wide voltage range! I wouldn't recommend this circuit there, you'd probably end up blowing all of your transistors. I'm sure there are some much more useful boost converters than this one for that voltage range.

pvang11 month ago

M.nimith,

Look up LM2577. There are schematics online. This IC will do what you're asking.

Paul

pyrohaz (author)  pvang116 days ago

Exactly that! Cheers Paul

M.nimith2 months ago

Hey dude, You got any equation? I wanna make one from 5v-12v.

pyrohaz (author)  M.nimith16 days ago

Hey man,

Unfortunately not, the left transistor will only oscillate ~8v and above, sorry!

Neon-A made it!2 months ago
It was great ... but i made it just a bit little stronger ... :)
temp_2030393603.jpg
pyrohaz (author)  Neon-A16 days ago

Good job man! :)

Giedriuus2 months ago

What is the efficency of this circuit? And about what current does it take to transform the voltage? I am asking this because I made a tube preamp using 12v battery, but the signal is very very quiet so I need to boost the voltage in the cathode but I also need to be aware of how much energy it would draw and if it would be worth it as the battery is only 5mAh. :\

pyrohaz (author)  Giedriuus16 days ago

I'm pretty sure the efficiency of this circuit is quite dire to be honest! You could make a much better booster based around the joule thief circuit if you want to drive a vacuum tube!

blorgggg3 months ago

Oh this is super great to know! Will probably work as a super extra DIY version of the booster in my brain and muscle zapping projects:

http://www.instructables.com/id/Snow-Crash-Electronic-Hallucinogen/

pyrohaz (author)  blorgggg16 days ago

I wouldn't recommend it! This supply isn't current limited, outputs DC and isn't as high voltage as required for that head gear. Cool link though!

PsychoPanda3 months ago

Heya, if the voltage source is applied to the output, would that then decrease the voltage and increase the current? thank you

pyrohaz (author)  PsychoPanda16 days ago

Hi!

I'm not too sure I understand your question... If you want to decrease the voltage and increase the current through a switch mode power supply, you should be using a Buck converter :)

adibayor3 months ago

can you give me the schematic diagram with proper input and where the output is? i need this for my project. thank you

adibayor adibayor3 months ago

btw i want to make it as 2 volt input and get the output of 12 v. can you help me?

pyrohaz (author)  adibayor16 days ago

Hey buddy,

Unfortunately, this circuit wouldn't work with a 2V input as the left transistor won't oscillate, sorry!

JyotismanR4 months ago

I want 3 v 120 ma output from 3 v 16 ma input...How can i do that?

pyrohaz (author)  JyotismanR16 days ago

Unfortunately you can't do that! You'd essentially be making energy from nothing and thermodynamics don't like that!

HusseinA6 months ago

Hi dear,
1st of all thanks for sharing your knowledge which reflects your professionalism and humbleness..

My name is Hussein, I have tried to simulate the circuit you made using Multisim but i got 12v in negative in the output!

may you kindly assist me how you simulate it? and email me with the circuit diagram if you have ?

Thanks and very appreciated in advanced

HUSSEIN AL-GAILANI
h.algelany06@gmail.com

pyrohaz (author)  HusseinA16 days ago

Hey buddy! I don't actually know any simulation packages that will effectively simulate the breakdown effect of a transistor meaning the left transistor won't oscillate in simulation and nothing should happen! Getting negative voltages however seems pretty weird!

Ghild.Zero1 year ago

which the control component ?
I want input 3 V and output ~100 V

thank you in advance

pyrohaz (author)  Ghild.Zero16 days ago

There isn't realistically a control component! The transistor on the left produces an oscillating waveform through controlled avalanche breakdown. This waveform then drives the transistor on the right in a feedback-less mode. Its just fortunate that applying a pulse wave to an inductor will create a voltage due to the inductive kickback effect! There is no control and its a completely open loop circuit.

How can I get a higher voltage with a lower input(or not)? With a higher mH's inductor? Thank you.
pyrohaz (author)  GuardJanissary16 days ago

For a constant switching frequency, increasing the inductor will result in less stored energy per cycle as the inductor realistically has to "charge" up with current, a lower value inductor will have more current than a larger value inductor for a constant switching frequency. As all of the inductor current gets dumped into the output capacitor after each cycle, more current = faster voltage rise. Other circuit aspects are what actually affect the output voltage!

Can i modify it to 12v to 30-32V only ?
pyrohaz (author)  hlmasterchief9316 days ago

Because its a free running oscillator that just happens to be driving a transistor and inductor, actually tuning this converter is pretty inefficient, by the time you had tuned this to do anything useful on the voltage front, you might as well have designed a much more useful one using a 555 timer or something!

anvit4 years ago
Hi,
the TIP 122 becomes very hot just after i apply 12 v .

Is it getting short ?
KITKAT69 anvit3 years ago
yeah dude was that the same thing that happens to you???? my VU meter only jumps to about 20V+ then suddenly decreases, then when i touch the TIP122 i got a minor burns man even if my input was on 6v..... and I wonder how many amps does that max 73v comprises....... I got a V-DUB using 555 timer and my theory works even if the input was only 6v 4.5a, I may say its a V-quad not a V-Doubler, since my input 6v was double up then the 2nd v-dub even doubles it up so i got 18v+ but it only got low current only for small circuit applications......

Anyone who wants my circuit about V-Quadrupler is welcome...... hence I though it would power up my gun....
I need to convert a 6v 4.5A battery into 12v that can give around 2A or more current
any schematic? Voltage doubler circuits on the web gives around 100mA which is not sufficient for motor driving. Thanks...
hey dude do you want my V-Quad circuit (Voltage Quadrupler circuit) its has two DC voltage doubler circuit based on IC LM555 hooked up in parallel in a small circuit board, it only got around 800ma current though.....
pyrohaz (author)  KITKAT6916 days ago

Hey man! Realistically, this is a pretty poor boost converter, its a pretty bad design and consists of parts I found in the base of a CFL, sorry if you lost any parts during the build process!

Neon-A4 months ago
Neon-A4 months ago
mspencer86 months ago

I am planning make this one with the input of 3v and output of 12v with 1 amp... can somebody help me? thanks..

pyrohaz (author)  mspencer85 months ago
Hey buddy,

For your converter, with an efficiency of 90%, you're looking at a switching current (from the 3v supply) of roughly 4.5A. While this is possible to make using discrete components, you'd probably be much better off using an integrated circuit!

Sorry I couldn't help much more!
Harris
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