Electronics > Projects, Designs, and Technical Stuff

10A current source with 10V compliance

(1/6) > >>

Terry Bites:
I'm labless for now. Moving house is such a pain.

Maybe some one can try this simulation (maybe in copper!) in another app.
It seems very, maybe too well behaved to me.
My objective is ccs capable of 10A @ 10V at up to a kHz into a resistive load.
It uses no exotic components. Its nicely retro.
My sim was done in microcap12

David Hess:
That will certainly work with perhaps some adjustments for stability.

Did you consider configuring the output transistors so that they drive the load with their collectors, which are inherently current sources, instead of their emitters?

I would also ground the output of the operational amplifier through a resistor to turn the supply outputs into current sources.  And then the output can be tied to the inverting input through a capacitor for frequency compensation.  As shown the low output impedance prevents the feedback capacitor from doing much.

Interesting topology, agree for a current source taking the output from the transistor collectors seems better. Regarding the capacitor C1, it works into the R1 10K resistor, so the low output impedance doesn't matter.


David Hess:

--- Quote from: mawyatt on May 20, 2023, 02:49:01 pm ---Regarding the capacitor C1, it works into the R1 10K resistor, so the low output impedance doesn't matter.
--- End quote ---

The low output impedance at the emitters divides the output impedance of the operational amplifier to attenuate the voltage change on the output, and that output impedance changes with output current, so the frequency compensation is changing with output current.  As the output current increases, and as the load impedance decreases, the capacitor effectively becomes smaller so there is less frequency compensation.

What's the purpose of Q1 and Q4? You already have current limitng.
Those two transistors can cause excesive high frequency oscillation when they start being active.
I'd suggest that you remove them alltogether.


[0] Message Index

[#] Next page

There was an error while thanking
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod