The simplistic Salas low voltage shunt regulator

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Just finished the Reflektor and it fired ok. Looks promising. very stable on the bench with a 1kr load.

Very easy to set voltage out.

Strangely, I set it to 10.00Vout and it is loosing voltage with time... 10.00 ~9.99 ~9.98.... As it heats up.

I will let it running for a while now.

My choice of 3r3 // 10r for R1 was spot on.... It is running at 250mA.
 
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As it heats up some things change a little, like Vgs, Vbe(s), let it come up and then fix it with the trimmer.

Trimming after it is hot provides very stable 10.00Vout.

What seems strange is that when powered from cold, it takes 10 seconds to reach 10.13Vout and then starts to go down. It takes 10 minutes to stabilize at 10.00Vout.

In all my other regs the voltage only goes up until it stabilizes.

I will now build a second shunt so I can test them in my p2p DCB1.
 
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As far as I can recall, all/most of my Salas type shunt regs dropped in voltage as they warmed up to final operating temperature.

I don't recall which transistors, but one or two had a +ve temp coef.

I never fully understood the temp coef mechanisms to make any sense of how to significantly improve temp stability. Keep it cool works !

Reading Roender's amp with it's various temp coef corrections was a revelation for me.
 
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