Is there a simple way to get 36v dc from a 12v battery (only need 20mA)?

Hi to all,

Just looking around the net for ideas on how to get 36v dc from a 12v battery.

It is for a lighting project and I'm using a strip of LEDs pulled from a dead laptop screen.

The strip has 27 surface mount 1206 LEDs and is very bright when running at only 15mA, though they are rated at 20mA I probably would run them at 15 for longevity.

The problem is that the LEDs are in series of 9s and each needs 2.8v ! I did consider rewiring them but the tracks are so tiny that I gave up on that idea quickly.

I seem to remember from many years ago making a voltage multiplier from just diodes and caps I think, would this be reasonable considering I only need the 36v to be at 20mA or less?

I would like to keep it as simple as possible using discretes if I can.

Edit: Just realised that each string will need 15mA so I would need 50 to 60mA to be safe!

Any ideas guys?

Thanks Al

Might be possible to scale up a Joule Thief.

You should be able to use a voltage tripler circuit driven by a 555 configured as an astable multivibrator. Higher operating frequencies allow the use of smaller capacitors in the tripler, but at some point the 555 loses will start to increase.

Edit: For 50-60mA you may need a buffer amp at the 555 output to drive the tripler, since the average tripler input current is at least three times the average output current.

Hi Guys,

just discovered an IC (TL497) in my bits box that may do the trick?

I have read the datasheet but don't fully understand it, can anyone confirm if it would do the job?

Here is the sheet. Al

just use a step-up dc converter like this one
**broken link removed**

Hi bigal_scorpio,

if you don't want to mess around with inductors and Schottky diodes here is another solution:

Aimtec (Canada) manufactures DC/DC converters in a small package.

The AM3N-1218S generates 18V output voltage at 12V input voltage.

All inputs and outputs are isolated and can be connected in any suitable configuration.

This device is manufactured in a DIL-24 package with package dimensions of 31.75X20.32mm (1.25X0.80"). The AM3N-1218S supplies 18V at 167mA.

Connecting two of them in series you'll have a +/-2% output voltage of 36V.

For more info use: Aimtec / AC-DC Converters / DC-DC Converters / Modular Power Supplies

Boncuk