Multiple regulators - What is the end-output-impedance?

kumori · 23rd November 2012, 05:56 PM

Hallo,

I have a question about using multiple voltage regulators after another.
Is the output impedance, that the circuit "sees" just the output impedance of the last regulator used?

For example:

Transformer ---> CRC Filter ---> Gyrator serial reg --> Shunt regulator

Let´s say we have 1 Ohm Serial R in the CRC Filter, the Gyrator has an output impedance of 1 Ohm, followed by a shunt reg with 0.001 Ohm output impedance.

What does the powered circuit know about the 1+1 Ohm serial resistance, when the the last regulator stage has very low output impedance?

I guess also the size of the reservoir or decoupling caps comes into play, but can anyone give a reliable "rule of thump" or something similar?

Thanks
Florian

peranders · 23rd November 2012, 06:00 PM

The shunt regulator determines the output impedance.

kumori · 23rd November 2012, 06:01 PM

OK, well that was easy.
Thanks.

jcx · 23rd November 2012, 06:16 PM

the (active) shunt reg determines the small signal output impedance

but once you try drawing more than the shunt reg bias current it cuts off and the output Z rises

23rd November 2012, 05:56 PM	#1
kumori diyAudio Member Join Date: Mar 2011	Multiple regulators - What is the end-output-impedance? Hallo, I have a question about using multiple voltage regulators after another. Is the output impedance, that the circuit "sees" just the output impedance of the last regulator used? For example: Transformer ---> CRC Filter ---> Gyrator serial reg --> Shunt regulator Let´s say we have 1 Ohm Serial R in the CRC Filter, the Gyrator has an output impedance of 1 Ohm, followed by a shunt reg with 0.001 Ohm output impedance. What does the powered circuit know about the 1+1 Ohm serial resistance, when the the last regulator stage has very low output impedance? I guess also the size of the reservoir or decoupling caps comes into play, but can anyone give a reliable "rule of thump" or something similar? Thanks Florian

23rd November 2012, 06:00 PM	#2
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	The shunt regulator determines the output impedance. __________________ /Per-Anders (my first name) or P-A as my friends call me Tube Buffered Gainclone in work \|Thread

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23rd November 2012, 06:01 PM	#3
kumori diyAudio Member Join Date: Mar 2011	OK, well that was easy. Thanks.

23rd November 2012, 06:16 PM	#4
jcx diyAudio Member Join Date: Feb 2003 Location: ..	the (active) shunt reg determines the small signal output impedance but once you try drawing more than the shunt reg bias current it cuts off and the output Z rises