Purpose of R1 in shunt regulator?

Thread Starter

spinnaker

Joined Oct 29, 2009
7,830
MikeML was very nice to post this shunt regulator for me. Can someone please tell me tje purpose of R1?

A guess is that it limits the date current on the FET but it being tied to the cathode of the TL431 confuses me a bit, unless it is also limiting the current there too.


The reason I ask is that I do not have any 470 ohm resistors. I have a couple of 240 ohm resistors. Will they do?


Looks like the Shack carries 470. Hopefully they have them locally but it would be nice to know if I have other options.




 
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beenthere

Joined Apr 20, 2004
15,819
R1 keeps the current through the reference diode (U1) to a safe level. Two 240 ohm resistors will do fine (in series) as a substiturte
 
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