[R-390] Regulated filament voltage

[Drew P.]

On 3TF7 BallasTube substitution, Henry wrote:

>Thanks David  - I clicked into DL's www and can see he wrote did exactly
>that kind of mod in 04.
>He cleverly does this using a plug-in mock tube construction.

Even more clever is the high tech plug-in regulator designed, built, and tested a few years back by list heavyweight Dave Wise.  His device is no larger than a 3TF7, is truly 2 terminal (does not need a ground lug unlike most other regulator schemes), regulates closely, and dissipates no heat to speak of.  He did this with a microcontroller, driving a pair of MOSFETS in a zero crossing phase control scheme.  This results in little to no RF noise production.  

Now, I can envision the wheels of Dave's mind turning as he implements a way to accomplish 2 terminal series voltage regulation in place of current regulation, all with just a software revision to his present design.

Drew