09-12-2016, 06:24 PM
(This post was last modified: 09-12-2016, 06:28 PM by Mike Watterson.)
I'd use a 3VA 220V to 9V mains transformer. It will manage DC of anode current of battery or low power mains Anode out.
A 12VA transformer for 2W to 6W valves. (Derate the power due to lack of air gap for DC).
Never use Toroid except on matched push pull. If Push-pull, then you can actually "uprate", i.e. a 6VA 110 + 110 primary will manage near 8W to 12W as the power capacity of a transformer rises with frequency. Hence some USA 60Hz 117 or 120V radios or amps with cheap transformers can't handle as much power on 50Hz, so run them at 110V.
More spec LT700, the output type for small speaker or headphones for push pull transistor (150mW). The various LT44 types are interstage transistor use, like in pocket radio, not suitable except to drive 2K phones!
lt700.pdf (Size: 89.62 KB / Downloads: 1)
A 12VA transformer for 2W to 6W valves. (Derate the power due to lack of air gap for DC).
Never use Toroid except on matched push pull. If Push-pull, then you can actually "uprate", i.e. a 6VA 110 + 110 primary will manage near 8W to 12W as the power capacity of a transformer rises with frequency. Hence some USA 60Hz 117 or 120V radios or amps with cheap transformers can't handle as much power on 50Hz, so run them at 110V.
More spec LT700, the output type for small speaker or headphones for push pull transistor (150mW). The various LT44 types are interstage transistor use, like in pocket radio, not suitable except to drive 2K phones!
lt700.pdf (Size: 89.62 KB / Downloads: 1)
