Forums » General Electronics Discussion

Hello, I am new to this site and it is long since i studied electronics. Can someone please suggest an easy way to make a DC voltage source with capped current output. I wish there was an element for this.

Here's a way to do it:

https://www.circuitlab.com/circuit/ns9k5b/cunning-current-source-01/

:)

Thank you for answering, but my skill level is too low to understand how to use that example. I am looking to generate a 12 V DC supply that is limited to 100 mA no matter what the load. Is there a simple way to make this?

I've made a simplifed version here:

https://www.circuitlab.com/circuit/ym5m25/current-limited-dc-source/

Just copy and paste everything inside the dotted box into your circuit.

:)

this is great. thanks a lot. am i right to assume this supply emulates the behavior of the laboratory power supplies that are used in schools and universities for powering students analog circuits?

@santanor,

" am i right to assume this supply emulates the behavior of the laboratory power supplies that are used in schools and universities for powering students analog circuits?"

That depends on the type of PSU you are using.

To a first approximation, the model simulates the behaviour of any generic PSU that has a constant current limit on its output.

This is the most common type of PSU used in schools, universities and industry development labs.

The model does not simulate any of the dynamic behaviour of a real bench supply. Line regulation (deltaVout vs. deltaVin) is obviously not modelled. Load regulation (deltaVout vs. deltaIout) is only very crudely modelled.

Transient response behaviour (under/overshoot, ringing and settling time) are not modelled.

Output impedance is not modelled but this can be added simply as a series resistance and/or inductance with any required parallel capacitance to ground between the PSU output and the load.

The PSU output is noiseless.

The exact behaviour at the boundary between constant voltage and constant current output is not modelled. The transition of the model may be sharper than for a real supply.

If the PSU you're using has what is called foldback protection or is a switched mode supply with pulse by pulse current limiting then no, it does not emulate that type of PSU.

Is good yes?

thanks again! it makes me feel welcome and i am glad i joined as i had doubts about the usefulness of this with my limited experience level. i am looking forward to playing around with this. have a nice weekend!