Constant Current circuit

**vargose** · 07-15-2009, 10:38 AM

http://www.instructables.com/id/Powe...stant-current/

I am trying to adapt this circuit for our purposes. The only problem with it currently is that the MOSFET get pretty hot at 200ma, after that you have to add a heat sink. Maybe a different MOSFET wouldn't get as hot. Any ideas? Or any other constant current circuits we could use?

Here are some by the same author.
http://www.instructables.com/id/Circ...h-Power-LED_s/

**Onli-Won Kanomi** · 07-15-2009, 02:07 PM

I don't understand why you would want to run a saber constantly? Are you planning to use it in signage?

**vargose** · 07-15-2009, 02:18 PM

The current is held constant. So it doesn't drop as the voltage drops. Like a buck puck. Thats what the circuit is for.

**Onli-Won Kanomi** · 07-15-2009, 05:15 PM

I misunderstood...thanks for clearing that up.

**Thaxos** · 07-15-2009, 07:55 PM

Interesting circuits, I'll have to take a closer look after the weekend. Bit busy right now. They look potentially viable though.

**vargose** · 07-16-2009, 07:12 AM

Here are the heat sinks we could use on the mosfet. http://www.mouser.com/Search/Refine....atsink&FS=True

We might be able to use the 1A driver I found instead of the above, more complicated, circuits. http://www.catsemi.com/datasheets/4101.pdf

**Thaxos** · 07-16-2009, 07:04 PM

I'm pretty sure I have the time to hook one of these up after the weekend. I probably have half the components kickin around already!

**mihunai** · 07-17-2009, 05:27 AM

why not just use a buckpuck instead of some complicated circuit?

mTm

**vargose** · 07-17-2009, 07:41 AM

Because the complicated circuit only costs a few dollars. Very Cheap in comparsion. More effecient than a resistor and not nearly as expensive as a buck puck.