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OUCH. Zener regulators on filaments

209.180.136.195

Posted by VoltSecond on June 6, 2001 at 23:20:38

In Reply to: zener regulators posted by eedork on June 6, 2001 at 10:34:54:

I wouldn't shunt regulate a filament.

Zeners below 5V have terrible regulation.
Zeners above 6.8V are noisy.

Shunt (zener) regulators blow a lot of power. The last one I did, the zener regulator burnt about two times the output power at high line.

Think CLC or LCLC for this purpose. I posted some values that should be close to working last month. Search for CLC.

If you really want to play:

Current Source Fed Shunt regulators are more efficient, but they are a lot of circuit for a filament. Precision feed 110% of max needed filament current with a current source (a BJT pass element is best) and build a diff-amp/ voltage reference/ MOSFET shunt regulator. MOSFETs are great for shunt regulators because their parasitics tend to make a good AC short to ground.

You could also use the MOSFET for a capacitive multiplier instead of a regulating shunt regulator.

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