T-Reg: High-Voltage Regulator for Tube Amplifiers, Back in Print
Elektor has picked up the T-Reg in its circuit series, a high-voltage regulator for tube amplifiers. The project comes from Jan Didden and first appeared in March 2009; CJ Abate reintroduces it on May 19, 2026.
The purpose is quickly explained: hum, residual ripple and noise on the anode voltage degrade the sound. The regulator delivers a clean, stable high voltage and is suitable for tube preamplifiers as well as power amplifiers. The output voltage is adjustable up to 500 V, and the pass element can be either a vacuum tube or a MOSFET.
What I find interesting is the turn-on protection. A CMOS 555 timer (IC1) pulls down the LED in IC3 with a delay after power-on; the delay is set by R8 and C3 and, with the given values, is about 30 seconds. IC3 contains an LED that drives an optotriac; when it lights, the optotriac fires thyristor TH1, which applies the rectified high voltage to the pass tube. The control and reference circuit is powered from the tubes' heater voltage via bridge rectifier B1 and capacitor C2.
The editors point out that the article is more than 15 years old and some components may no longer be available. It is mainly meant as inspiration for a new design. The text lacks a complete parts list, and the schematic is included as an image. Anyone working with high voltage should of course be especially careful.
Source: Elektor
The purpose is quickly explained: hum, residual ripple and noise on the anode voltage degrade the sound. The regulator delivers a clean, stable high voltage and is suitable for tube preamplifiers as well as power amplifiers. The output voltage is adjustable up to 500 V, and the pass element can be either a vacuum tube or a MOSFET.
What I find interesting is the turn-on protection. A CMOS 555 timer (IC1) pulls down the LED in IC3 with a delay after power-on; the delay is set by R8 and C3 and, with the given values, is about 30 seconds. IC3 contains an LED that drives an optotriac; when it lights, the optotriac fires thyristor TH1, which applies the rectified high voltage to the pass tube. The control and reference circuit is powered from the tubes' heater voltage via bridge rectifier B1 and capacitor C2.
The editors point out that the article is more than 15 years old and some components may no longer be available. It is mainly meant as inspiration for a new design. The text lacks a complete parts list, and the schematic is included as an image. Anyone working with high voltage should of course be especially careful.
Source: Elektor
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