Tube Heater Power Supply PCB (6.3VDC from 6.3VAC)

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Tube Heater Power Supply PCB (6.3VDC from 6.3VAC)

Postby maynard999 » Sat May 17, 2014 1:58 pm

These are extra PCBs from a personal project. Tube amp builders know that it's nearly impossible to get 6.3VDC from the 6.3VAC winding on typical transformers. It is, however, possible with Schottky diodes and a super low dropout LDO regulator. No commercial PCBs exist for this so I designed one. It's 5cm X 10cm and made with 2 ounce copper traces on a 1.6mm PCB. All the components are designed for up to 5A of current and I've tested it up to 4.2A. The ripple reduction and heat dissipation will work best if it's used to preamp tubes only and the current is kept reasonable. There are very few applications where more that 2.4A of current would be needed (4X 6SN7 tubes) and this is what I really designed it for. I can't think of many applications, but this can be used to rectify 12VAC or 12VDC into 12.6VDC. That's about the max for this design. The final output voltage is dialed in with a trim-pot for added flexibility.

I'll include a BOM from Mouser with each order (see below). Link to these on Ebay are below. Feel free to contact me directly or go there to buy one. It's a simple circuit so feel free to wire it point to point using the schematic I've supplied on the Ebay add and skip my PCB.

http://www.ebay.com/usr/hvforless

Qty Mouser # Desc
4 511-STPS5L40 Schottky Diodes & Rectifiers 5.0 Amp 40 Volt
1 281-100-RC Metal Oxide Resistors 100ohms 5% Tol
1 647-UFG1C102MHM Aluminum Electrolytic Capacitors - Leaded 16volts 1000uF 85c
2 647-UKA1C103MHD Aluminum Electrolytic Capacitors - Leaded 16V 10000uF -55 to 105C
2 505-MKP20.1/100/5 Film Capacitors 100V .1uF 5%
1 998-MIC29502WT LDO Voltage Regulators 5.0A LDO Adj. + Shutdown(ROHS Compliant)
1 594-64W102 Trimmer Resistors - Through Hole 3/8"SQ 1Kohms Multi Turn Cermet
4 505-MKP20.01/100/5 Film Capacitors 100V .01uF 5%
1 532-4880M Thermal Interface Products MOUNTING KIT TO-220
1 532-513102B25 Heat Sinks TO-220 VERT 11.0 TR EXTRUDED W/FINS
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Re: Tube Heater Power Supply PCB (6.3VDC from 6.3VAC)

Postby maynard999 » Tue Oct 21, 2014 9:07 pm

I tweaked this board and ordered a bunch for my use (and extras for Ebay). Biggest change is a voltage doubler circuit via a jumper. Switch between 6.3V and 12.6V tube without pulling out your soldering iron. I also added a 1/4 B+ reference since I had room.

I also made another board that incorporates a high voltage section in addition to the LV circuit described above. There a few more extras with this universal PS. I needed a circuit for a headphone amp that used high current tubes. This board handles it, up to 4.5A of DC heater current. The one described above had the high current components, but not the heat management. This one has large heat sinks on the voltage regulators and even heat sinks on the heater rectifying diodes. The other extra is a house chassis isolation circuit. Basically everything you could possibly want for a Pre-Amp or SET power supply all on one small board up to 400VDC.

Take a look at my Ebay page for more info.
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Re: Tube Heater Power Supply PCB (6.3VDC from 6.3VAC)

Postby SteveH » Sat Oct 25, 2014 6:10 am

Very interesting - thanks !
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