On 2019/08/26 8:24 p.m., Arid ace wrote:
On Mon, 26 Aug 2019 19:22:35 -0700 (PDT), wrote:

A little homemade 1920s 1 valve set with direct heated triode (unmarked). I've traced most of the circuit, looks very simple. Not tried to trace the main coil assembly with its 6 connections yet. The valve has a grid leak resistor for -ve bias without C battery. It runs high R phones, no speaker. 1st question is what sort of HT voltage and/or anode current should I aim for?


NT

One triode from that era is the A415. The datasheet lists Va between 20 and
150V, saturation current of 30 mA and default anode current of 3 mA.


Indeed, you need to know the tube value to be sure, but consider the
cost of batteries of the day and thus the B+ is likely 45VDC or thereabouts.

In those days some people made their own B+ batteries - way back when I
was a kid digging through attics in Toronto (mid 1960s) for old battery
sets I found a couple of home-made lead acid batteries that were glass
test tubes about 8 inches long mounted in a wooden box and there must
have been 15 to 20 in each case. Wish I still had them as they were
classic home-brew stuff which I always loved from the battery age of radio.

John :-#)#

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