Scorpion Tube power Supply Build Thread

[Joe Malone]

The Scorpion works wonderful in my 1 Ru mic pre.

Wow Holger that is a super neat and compact dual tube pre. Amazing.

(I copied the photos locally on to the forum as they weren't showing for some reason)

[STUDIO315]

Hi Joe,

I am checking to determine if the Scorpion would be able to sufficiently power the Collins 356E-1.

The power requirements from the unit instructions are as follows:
300 vdc at 77 milliamperes
6.3 vac at 1.55 amperes

Any help in confirming would be appreciated.

Thanks,

Nathan

[STUDIO315]

Ok - using the calculator Joe provided it appears this power supply would not be a good fit:

(21*1.55)+(320*.077)=57.19=meltdown

Nathan

[Joe Malone]

Ok - using the calculator Joe provided it appears this power supply would not be a good fit:

(21*1.55)+(320*.077)=57.19=meltdown

Nathan

Yes correct. In the new year I will have a new HV supply that uses a normal off PCB toroid for the first transformer. So a 80VA or large can be used to run the filament and 48v phantom and so the whole 30VA can be used for the high volts which will work for a huge amount of vintage tube gear.

[willgmr]

Hi,
Is 300v the top output range based on the regulator or the VAC rating of the included transformer?
I have an old preamp that wants 320V at the first stage and 200V at the second.

[Joe Malone]

Hi,
Is 300v the top output range based on the regulator or the VAC rating of the included transformer?
I have an old preamp that wants 320V at the first stage and 200V at the second.

There is 320vdc unreg available on the pcb but the 2 x 150v zeners in series limit the regulator to 300v.

[willgmr]

Thanks for the reply. Possible to change those zeners to 160V versions? Or add another 20V in series?

[Joe Malone]

Thanks for the reply. Possible to change those zeners to 160V versions? Or add another 20V in series?

You need to have some volts to regulate. So if you get 320v unreg (which will depend on the mains voltage where you are and the load on the hv rail) you could probably go to 310v by adding a 10v zener in series with one zener.

Remember if the original power supply was unregulated the 320v probably sags in use to less than 320v any way. So 300v regulated will be fine if not better for 99% of tube gear as it is on 5% out. In most tune gear I see +/-20% in power rails.

[willgmr]

Thank you for your input - I think you’re right regarding voltage sag and unregulated supplies. I will give this supply a try when I’ve got the time to open up this project. Thank you!

[Joe Malone]

Thank you for your input - I think you’re right regarding voltage sag and unregulated supplies. I will give this supply a try when I’ve got the time to open up this project. Thank you!

Biggest thing is make sure you use the maths shown on the website to check the filament Watts and hv watts is total less than 30VA. If not sure ask me to check if it will work.

I am working on larger Scorpion which uses off pcb normal toroid for filament and pcb toroid for high volts to do bigger projects but it isn’t finished yet.