Hello Again
I have a small circuit that is made to switch 5, 5mm LED's on and off randomly, i want to add more LED's and larger ones so i though about a relay but they aren't fast enough. i cant really measure the voltage as when i connect the multimeter it changes too fast to get an average. i need a MOSFET that will turn on easily with the 5mm LED voltage

Thanks, Chris

 

If you can't measure the voltage at the LED, what is the voltage at the supply? Some mosfets are made that turn on with as little as 2.5V (e.g., STS5PF20V, which is P channel)? Can you provide your schematic?

John

 

Or, use a bipolar transistor and a base resistor that give you a reasonable base current (say 1/20 of the desired LED current). That could be operated off any voltage down to less than 1.

 

The supply is 9V
When i measured it i saw it jump from 1.5v up to 8v, the circuit is a TIP31C Transistor with an audio (P2) connecter, you plug it into an audio output and it beats the the music.

So that is all of the specs i can give now i just need the MOSFET

 

This is the schematic i put an arrow where i want the mosfet to be so i can connect about 30, 10mm white/Blue LED's

Chris

 

Any one know any answers?

 

Hello,

Take a look at Bill's thread on:
LEDs, 555s, Flashers, and Light Chasers
http://forum.allaboutcircuits.com/showthread.php?t=19075

Bertus