ark@rabbit.UUCP (10/28/83)
My Heathkit power amp (250W/channel) has two 13,300 microfarad filter capacitors, rated at 125V and run at 100V. Needless to say, it would do a good job of blowing fuses if there were not some way to spread the load at turn-on. This amplifier uses a temperature-sensitive resistor in series with the power transformer primary. I think its resistance decreases as it gets warm. In addition, there's a relay that runs off the DC power supply voltage. When that voltage gets large enough that the capacitors can be considered almost all charged, the relay closes. This (1) shorts out the temperature-sensitive resistor so the power line goes straight into the transformer primary, and (2) latches the relay so that later transients won't cause the relay to open even if they momentarily deplete the capacitors.