Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Gainzilla on August 28, 2017, 03:43:38 pm

Title: Hoffman relay power supply board for D.C. Elevated heaters?
Post by: Gainzilla on August 28, 2017, 03:43:38 pm

hi all,


Wondering if I can use the Hoffman relay supply board to power D.C. Elevated heaters. The schems I've seen show a bridge rectifier (20A) and an eCap powering the filaments. Would I just omit the voltage regulator, or is there a voltage regulator I should look for with maybe closer to 50v?


Schematic below (hand-drawn looking one), then the Hoffman Board & Schematic:

Title: Re: Hoffman relay power supply board for D.C. Elevated heaters?
Post by: shooter on August 28, 2017, 04:26:41 pm

not sure on using Dougs board as a starting point, I've done DC filaments twice, didn't get what I paid for :laugh:

Here's a snippit from a VOX (AC4?) that uses DC for the pre and AC for the power tubes

Title: Re: Hoffman relay power supply board for D.C. Elevated heaters?
Post by: PRR on August 28, 2017, 08:07:51 pm

6.3VAC will never make big *clean* 6.3V DC due to rectifier drops and ripple.

Neither hand-drawn plan is "elevated".

If you already *have* DC, you don't need the Hoffman board at all. Use your DC to power the relay. You can find 6V relays, or add a resistor to drop to 5V for 5V relays.

Title: Re: Hoffman relay power supply board for D.C. Elevated heaters?
Post by: Gainzilla on August 30, 2017, 01:45:32 am

Thanks, guys!