what do you guys consider high voltage?

hi
i'm trying to make a cap discharger and i need to know what kind of voltages i need to be protected from that way i know which resistors to pick from. i need to know what is the highest voltage i could ever possibly run into with audio equipment. then i need to know what are the highest voltages that a tv tech repairman may find?
thanks

In Audio - ca. 600V DC - at anodes of large output tubes.

It TV - some 35KV - at the HT for the tube.

And at the other end - I consider anything higher than 48V unsafe, and discharge before touching.

Jakob E.

From a TV technician viewpoint, HV can be anywhere from 150v on older tube types sets to 32,000V found on the ultor or 2nd anode of the CRT. You want someone experienced to teach you proper technique to discharge these safely.

Agree with above and would add - to me, high voltage is anything that's dangerous. I wouldn't knowingly touch anything over about 35. The danger threshold depends of many factors. Around water or on a boat, lower voltages can be lethal. I read a Navy technician who was killed by a 9 volt battery because skin punctures allowed extra current to flow.

In TV's the flyback cap can hold a big charge, as can the picture tube itself. You might need to discharge several times to get the voltage down to a safe level.

Generally 1 amp of initial discharge current seems about right - not too big a spark. So you can figure about 1 ohm per volt, easy to remember. For a big 30 volt cap 30 ohms, for 600 volts 600 ohms, etc. You could go higher, but I wouldn't go lower.

If you're going to be discharging CRT's, you want to use a big bleeder resistor, 2 or 3 meg ohm minimum with proper isolation and insulation. This equates to about 17ma at 35,000V a highly lethal current!! Abruptly shorting this to ground without bleeder resistors can tear the aquadag conductive coating off the inside of the tube rendering it useless. Same thing with caps, electrolytics can be damaged by collapsing the built up internal charge to quickly. You want to select the bleeder resistor according to the voltage to be bled off versus how quickly and safely the cap can be discharged. For a 600V B+ filter, a 15K 5W wirewound resistor should work nicely. Never trust a cap to be completely discharged, even after bleeding it. Always measure it after to be safe. Some low leakage caps can maintain quite a charge for weeks after the supply is shut down, especially in the case of CRT's.

the caps we use to help combat sag on the power grid are shipped and stored with the terminals grounded...they grow a charge when left open circuit.

In audio circuitry, I start to be careful above about 80 or 90 volts on the workbench. But it's dry there and much below that I can't even feel. Unless I'm using a battery to power the circuit, then I'm careful right away. You can get a burn off of jewelery and a shorted battery very easily.

Danger comes in 2 forms High volts and high amps. A low volt signal at enough amperage can kill as can a high voltage with a low amperage can kill. It only takes a few milivolts to stop a human heart. Or in the case of a gold fish it takes 9V to get it going again. My buddy had a gold fish that died on him. He tapped the gold fish with the 2 terminnals of the 9V much like one would put in on their tounge as to see if it was working. Anyway the fish came back to life and lived another month. He was able to do this a second time. So gave the fish an extra 2 months in the bowl.