variable current limiter

[Gaston]

i have built a power supply very simular to this. the values may be a little off but i just drew it to show the basics of what i have. my question is about the current limmiter. i have tried a few different ways but cant get it to work. i want it to be variable so i can limmit the current to very low values when needed. the out put of the supply is ten amps. i get about 1 volt accross the shunt at the 10 amp output. so i figure i will put an op amp with a gain of 700 across the shunt that way i can limmit down to .001 amps. then i will make the base of a pnp transistor positive to shut down the base of the darlington controling the output transistors.

 

[Russlk]

Try this modification:

 

[ljcox]

I would reconfigure the op amp as a Schmitt Trigger.

Set the threshold to trigger at the voltage you want.

I'll post a circuit for you tomorrow.

Len

PS limit has onlt one m