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

[bigal_scorpio]

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

 

[blueroomelectronics]

Might be possible to scale up a Joule Thief.

 

[crutschow]

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.

 

[bigal_scorpio]

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

 

[carmusic]

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

 

[Boncuk]

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