• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Safety Practices, General and Ultra-High Voltage

Joined 2003
EC8010.... I did go to UK schooling and Uni during the slide-rule time.
A bit earlier than me, then. Brought up on log tables and slide rules, we were the first to be allowed electronic calculators in maths "O" level (1974).
I find it interesting that all my recent test equipment exposed to 30V rms and above immediately flags a dangerous over voltage. An overkill as one might say. Although now in Germany one looks back to those high risk days, that in perspective today´s lot should have no excuse for getting electric jolts !
Ah, but today's lot have no fear. They've been brought up in a sterile, danger-free environment, so they do not recognize danger when it lurks. When I was teaching, students would cheerfully rearrange their circuits with power applied. Although one managed to explode a 741, in general, solid-state electronics doesn't fight back.

In the end, it's all about attitude of mind; you need controlled and informed fear.
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The real sting in the tail of the POTS line was arranging for it to ring while someone had it in their mouth.
48V via a few k tickles, 90V @ 20Hz with enough grunt to ring IIRC 6 mechanical telephone bells is on a whole other level of ouch!

Penny ante solid state doesn't fight back, but may I introduce you to the hockey puck IGBT, when fed from a reasonably stiff 600V rail in a motor driver with plenty of bus cap, can and will detonate with a spectacular amount of flying shrapnel when something goes wrong, there are solid state things that warrant a blast shield.
Hello guys.

Will R99 bleed the B+ caps in my amp?



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