Quote:
Originally Posted by Electronic M
Yes but the grid resistors need to be 1-2 Megaohms not kiloohms. Once it is passing audio you may want to experiment with caps between .47 and .01, plate resistors between 8k and 15k, etc to optimize volume and tone. Audio amplifiers of that time were spectacularly inexact devices and could opperate deceptively normally with component values far from design or optimum.
What I gave you should get it to pass audio.
|
For posterity, here's the amended (final?) schematic with coupling caps and resistors bypassing the the two transformers:
Quote:
Originally Posted by Electronic M
You will need a high impedance speaker/headphones or an audio matching transformer and a low impedance speaker... the plate resistance of a 01A is 11k ohms so you want an audio transformer with a primary impedance between 9k and 13k, and a secondary impedance that matches your speaker. Any transformer rated over 5W is probably over kill.
|
I think I'm slowly becoming convinced that I should try this. I'll have to dig around my various parts stashes and see what I may have.
I know I have some 70V PA speaker transformers that came with some full range 8" Jensens- would they do the job, do you think, or would the primary impedance be too low? I don't know how to determine those impedances between the windings.
I have some other old 40's-50's radios out in the barn, I can see if I can determine the values of their output trannys.
Sorry for all the probably stupid questions.