Gingertube wrote:The EM87 Indicator circuit looks more complicated than is generally required - what were your design intentions/requirements for this?
I made a 1625 oddwatt with a eye tube, a 6AF6. Since the input varies from about 1.5VPP to 2.5VPP, you have to be able to display as much as possible and gently limit the display to keep it from crossing. The 6BN8 is a voltage amplifier, and rectifier. The 680K and 0.1uf cap gives me the display speed I want. A EM87 should have a 100K resistor on it's pentode, but I found a 470K, at least for me works better. The 220K and zener is a soft limiter. I have 10 EM87s and 6 6BN8s, all of them were different. I had to mix and match to get these 2 similar (the colors are a bit different). I don't show the diode on one the 2 EM87s cathodes, and 220ohm resistor on the other.
Gingertube wrote:Should we "Nit Pick" this superior design or just sit back and admire (with envy)? - well Ok, safety resistors from the bias pot wipers to raw bias supply side of the bias pots could be added.
I do have them installed, forgot to draw them.
At first I wanted to be a ET. Now I are one.