Tube amplifiers are cool and fancy. What about tube power supply?

Well... here you are:

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I bought a used mixing console with no power supply. Before I find one factory made, I made this temporary setup. Console requires 2 coils of 19VAC. This is exactly what I have from my 1A2 transformer (2 by 18VAC each). But this guy is dangerous: it’s a big transformer and rush-in/rush-out energy is huge. When you unplug it from current on primary side a higher voltage is induced in the low side. This killed an integrated rectifier (bridge) in my very first 4A Speakerphone, which I powered from this transformer. After several on/off cycles it died till I found the faulty bridge, resoldered it to just a jumper and since that time have to power from filtered 24VDC with taking care of polarity.

Since that time every transformer I work with gets a dedicated varistor from Siemens&Halske with rated voltage. However, quick checks this time showed that it doesn’t help with this transformer. Powering off induces ~100V peak on the 18VAC coil at power off. Looks varistors are slow triggered devices which can help in case of constant overvoltage.

Didn’t have time yesterday to bother with Zenner diodes, so just plugged in a 220V light bulb across both coils (36VAC nominal). It lights a bit during the operation in normal. Mode, but is supposed to absorb any of peak voltages at transition states. Similar to bulb protectors/fuses in some of old switches.

Simple things sometimes work so good in this world!!