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Re: Flash and thunder when turning on my amp

Posted by Doc B. (M) on October 26, 2006 at 09:33:30

In Reply to: Re: Flash and thunder when turning on my amp posted by xcortes on October 26, 2006 at 08:13:08:

My second solution really does the same job as cutting the B+ at, for example, the final filter stage. Put a switch in the connection from your power supply ground to the center tap of the HV supply, terminal 1T on the transformer. When you open the switch contacts you will create a "standby" condition where the B+ supply's current path is broken - just as effective as cutting off the B+ from the high side, and easier on the switch because you will be switching to ground potential and there seems to be less of a problem with the switch contacts arcing and being eaten up. Your ground will float with respect to the center tap until you close the switch, but we found that this does not seem to create any problems.

It's a little bit cumbersome because you do have to remember to open the standby switch before you throw the AC mains switch at startup. A more refined approach would be to build a B+ delay with a 555 timer circuit and a HV relay. However we used the simple switch as a cheap and easy retrofit on Paraglow direct coupled amps, which are a pretty close relative of that 45 circuit. You might or might not a hear a little tick when you close the switch. When it does happen it's pretty quiet.

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