[SOLVED] How to achieve 5A short circuit and maximun current for series voltage regulator?

[hanshen]

The figure shows multimeter at the output is in Ammeter mode which i think it functions as short circuit for the system.

Referring the picture, I attached. I have designed a series voltage regulator that can convert AC source to DC source (range from 0 - 20V). However, I could not achieve 5A maximum current (short circuit current). Initially, I thought it was the component that restraint me from achieve the maximum current desired. So I did change some of the component with higher power rating. However it seems to make no difference. Can someone point out where i make a mistake in designing the power supply.

 

[crutschow]

The 2N3055 likely doesn't have enough gain to deliver 5A from the limited output current of a 741. One option is to make it a Darlington pair (such as by adding a 2N2222).

You are aware that the 5A short circuit power dissipation will be over 150W with a 24VAC rectified supply(?). So continuous short circuits will require a humongous heat sink.

 

[hanshen]

I have tried in the simulation. You are right. Thanks a lot. I have spend a few hours, yet the fact that 2N3055 do not have enough gain just didn't cross my mind. Thanks again.

Regarding the power dissipated, thanks for the reminder. I will put that in mind. I will try to redesign the short circuit protection part.

 

[crutschow]

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Regarding the power dissipated, thanks for the reminder. I will put that in mind. I will try to redesign the short circuit protection part.

You can reduce the dissipation by going to fold-back or hiccup type limiters. These reduce the average short-circuit current.