• on Audio/Video/Photography
  • Published in issue 3/2009 on page 22
About the article


A high-voltage regulator for valve amps

This article describes a novel design for a high-voltage regulator that is very simple yet offers excellent performance. The output voltage is fully adjustable with a single resistor without any changes in performance. You can use several types of tubes or MOSFETs for the pass device in the circuit.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.

Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Extra info, Update
Quick Project Specs
- Universal design, output voltage easily adjustable with one resistor
- Low output impedance and low hum and noise over the complete audio band
- Output voltage adjustable between 0 and 500 V, up to 1 A output current
- Usable for valve preamplifiers and (single ended) power amps
- Build-in delay function (30 s) for output voltage after power-on
- Three plug-in options available for the pass device: with 6528 valve (max. 600 mA); with EL84/6BQ5 or EL86/6CW5 valve (max. 50 mA), or with DN2540 MOSFET (max. 1 A)
main board

R1 = 1kOhm3
R2 = 13Ohm3
R3 = 250kOhm (see text)
R4 = 330Ohm
R5 = 560kOhm
R6 = 3kOhm6
R7 = 470kOhm
R8 = 1MOhm
R9,R13 = 120kOhm
R10 = 12Ohm (see text)
R11 = 2kOhm2
R12 = 10kOhm
R14 = 820Ohm
R15 = 1kOhm

C1 = 1µF 560V MKT
C2 = 1000 µF 16V
C3 = 22 µF 15V
C4,C5 = 4µF7 300V
C6,C7 = 47µF 500V

IC1 = LMC555
IC2 = LM334
TH1 = C106M1G (thyristor for 600V 2.5A)
IC3 = TLP3052
T1 = BC556
T2 = 2SA1208
T3 = 2SC2910
D1 = 100V 5W zener diode
D2 = 15V 0.5W zener diode
D8 = 1N4148
D3,D4,D6,D7 = UF4007 (fast/soft recovery rectifier 1000V 1A)
D5 = LED, yellow, 5mm (.2") pitch
D9 = LED, red, .5mm (2") pitch
D10 = LED green, 5mm (.2") pitch
B1 = DF005M (bridge rectifier 50V/1A)

F1 = 1A fuse, round, plug-in
K1 = 3-way PCB screw terminal block, lead pitch 5mm (.2”)
K2,K3,K4 = 2-way SIL socket strip
K5,K6 = 4-way SIL socket strip
K7,K8,K9 = 2-way PCB screw terminal block, lead pitch 5 mm (.2”)
DIL-06 IC socket
DIL-08 IC socket
4 standoffs, h=12mm (.5”)
4 machine screws for standoffs
PCB, ref. 081089-1 from www.thepcbshop.com

6528 plug-in

R1,R2 = 1kOhm 0.5W, 1%
R3,R4 = 12Ohm 2W, 1%
V1 = 6528 or 6080
K2,K3,K4 = 2-way pinheader
K5,K6 = 4-way pinheader
PCB-mount Octal socket
PCB, ref. 081089-2 from www.thepcbshop.com

EL84/6BQ5 plug-in

R1 = 1kOhm 0.5W, 1%
V1 = EL84 (6BQ5) or EL86 (6CW5)
K2,K3,K4 = 2-way pinheader
K5,K6 = 4-way pinheader
PCB-mount Noval socket
PCB, ref. 081089-3 from www.thepcbshop.com

DN2540 plug-in

R1,R2 = 100Ohm 0.5W, 1%
R3,R4 = 5Ohm6 2W, 1%
D1-D4 = 15V 0.5W zener diode
D5,D6 = 100V 5W zener diode
T1,T2 = DN2540
K2,K3,K4 = 2-way pinheader
Heat sink(s) 4 K/W, e.g. Wakefield 637-20ABPE
PCB, ref. 081089-4 from www.thepcbshop.com
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