Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: 12AX7 on November 27, 2016, 12:33:35 pm

Title: question RE: PT tap
Post by: 12AX7 on November 27, 2016, 12:33:35 pm
I have a unused tap on my PT that has 3 wires, a common and 2 taps one for 6.3v and one for 5v. (no, the 6.3 isn't for heaters it has a dedicated heater winding) Is there a way to combine the 2 taps to get more V or a way to double one of them easily?
Title: Re: question RE: PT tap
Post by: kagliostro on November 27, 2016, 01:06:31 pm
This separated 0-5v-6.3v winding seems devoted to the tube rectifier (a 5v or a 6.3v rectifier)

Which is your purpose ? What do you want to do with this supply ?

Franco
Title: Re: question RE: PT tap
Post by: drgonzonm on November 27, 2016, 01:48:04 pm
Send us the data from the transformer.  We might be able to get a schematic for the xfrmr. 
Title: Re: question RE: PT tap
Post by: 12AX7 on November 27, 2016, 02:13:54 pm
I have one, but i think i've found a way to do what i needed. If it doesn't work out i'll post back but it seems to work.
Title: Re: question RE: PT tap
Post by: 12AX7 on November 27, 2016, 04:18:25 pm
This is what i wired up and it works tho i'm not sure how smart this is having about as much electronic theory as a chimp. So maybe someone can tell me if this is ok or will be problematic. Note the resistor with a ? next to it. I actually wired a 5k pot there and at 5k the LED still lights tho a bit dim. The relay coil is 100R as noted. The relay is rather 9vDC i think, but it seems to trigger strongly and reliably with 6.3v. If this is an ok way to go about it, what would you recommend for a resistor value? If not, how would you suggest i wire it?

Title: Re: question RE: PT tap
Post by: sluckey on November 27, 2016, 05:29:29 pm
What you have is fine. I'd use a 1K resistor. 470Ω would be really bright with 9V.

Title: Re: question RE: PT tap
Post by: 12AX7 on November 27, 2016, 05:34:31 pm
It's not powered by 9v, it's 6.3. I was just saying the relay may be a 9v but it works fine at this voltage.
Title: Re: question RE: PT tap
Post by: sluckey on November 27, 2016, 05:44:41 pm
It's not powered by 9v, it's 6.3. I was just saying the relay may be a 9v but it works fine at this voltage.
I know that. Now measure the dc voltage across that 470µF cap. Bet it's pretty close to 9VDC.
Title: Re: question RE: PT tap
Post by: 12AX7 on November 27, 2016, 05:46:53 pm
Ahh, i see. Thanks slucky.