Forum: Analog Circuits Dual supply with current limit

von giselach (Guest)

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I need a dual power supply for experiments with opamps. In order to not 
blow up my circuits too early I'd like to have some way to adjust a 
current limit.

The LM317 (and LM337) datasheet shows a current limiting application 
using a resistor from output to adjust pin. Based on that I also found 
the following circuit, which seems to serve my purpose pretty nicely:


The thing is, that the current sensing resistor (as they call it) at the 
output of the regulator gets the total current. That requires a special 
low value, high power part that I don't have in my collection and that 
seems bulky and expensive.

Can someone point me to alternative designs that don't require power 
resistors and are still similarly simple?

von MaWin (Guest)

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giselach wrote:
> That requires a special low value, high power part that I don't have in
> my collection

That's life.

Connect a few that you have in parallel to solve that problem.

Every other circuit will also have a problem that you don't have all the 
parts, and as you are too lazy to buy anything, there will be no 

I don't like your current limiting circuit, but an LM3080 will not help.

von Dieter (Guest)

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Tell first how exact this has to be. In case of smooth limits enough you 
should try current mirrors with simple power transistors.

Study this carefully:


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