Multiple switches

[Karl5150]

If a Quickie 1.1 was built with a separate on/off switch for the 36V and 1.5V supplies, is there a protocol for switching on one or the other first?
TIA

[caffeinator]

Hi Karl,

Typically, it's recommended that the filaments be turned on and heated prior to switching on the B+ to avoid "cathode stripping."  I'm not sure that's as great a concern for lower voltage tubes such as are employed in the Quickie.  In any event, I believe observing this practice would mean first switching on the 1.5V (think it's probably 3V total) and then the 36V.

Hope this helps,

David

[Karl5150]

Thanks David. I understand that with the heaters switched off on the Quickie that there is no draw on the 36V, but I am experimenting with the Quickie circuit used as the preamp section of an integrated amp that will supply about 50V DC for the high side.

[Paul Birkeland]

You don't really need to switch the 36V off since cold tubes won't conduct (this is one of the differences between 1.0 and 1.1).  I believe the 3S4 is designed to operate in this manner, so any old order you'd like to throw the switches should be OK.

[JamieMcC]

On a similar note I am about to start a similar project ie a quickie in front of a small power amp to make a all in one integrated. The power amp requires 2x19vdc 2Amp. I would like to power them both up from a single switch but am conscious that often a soft start function is required. Is there a rule of thumb to determine at what operating point this is required or is good practice to incorporate. I might add I am building separate linear power supplies for both the Quickie section and power amp section.

TIA
Cheers
Jamie

[ALL212]

hmmmm....  I wonder what small power amp requires 2x 19v power supplies....hmmmm

I'll bet I know!!  Sounds like a cool idea.  Don't forget to share!

[JamieMcC]

hmmmm....  I wonder what small power amp requires 2x 19v power supplies....hmmmm

I'll bet I know!!  Sounds like a cool idea.  Don't forget to share!

I'm still waiting for some parts but have made a start on ACA psu (still waiting for the transformer for the Quickie side to arrive. Its been a pretty educational project so far. 
 
So a teaser pic of progress from this morning.

One channels psu in prototype form (my first ever mock up)! Pretty pleased that it works and the voltages look ok (running without load) this should give me the flexibility to experiment with running slightly higher voltages and bias settings as some do. I need to install a permanent bleed resistor next to discharge the capacitors rather than using one on fly leads.