TubeCad Feedforward Shunt Regulator

[jayme]

Has anyone built a Feedforward Shunt Regulator, as described by Broskie on this page?

http://tubecad.com/2007/01/blog0095.htm

They seem to be quite ideal, and have a low overall complexity and part count, which is nice.

This one, in particular, intrigues me:


My question, however, is: If I don't have exactly a 40mA draw (my preamp draws more like 30mA) will I need to change any of the part values? What if I use one per channel, and reduce it to a 15mA draw...any changes then?


(I really need to learn how to model these in SPICE...)

[Robert McLean]

If I don't have exactly a 40mA draw (my preamp draws more like 30mA) will I need to change any of the part values?

The quick answer is no, the EL84 will conduct, or shunt, the "excess" 10 mA current away. But you will have to adjust Rk to get all this to happen at the voltage you want it to. Also R may have to be tweaked to match the real value of gm of the actual tube being used.

(I really need to learn how to model these in SPICE...)

By "these" do you mean shunt regulator circuits, or do you mean EL84 pentodes ?

If you mean EL84s there is a 6bQ5/EL84 model at Duncanamps.com.

If you mean regulator circuits or circuits in general then just get a hold of a free Spice, such as LTSpice and play around with it. I know theres all kinds of books and instructions you could get, but to me, its like DIY. Just get in there and do it. You cant electrocute yourself or blow anything up with spice.