Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. The sunn still shines online!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  
previous: nuke On the subject of standby switches ... -- 9/27/2000 9:54 PM view thread

Re: Engineering question about standby switches

9/28/2000 2:44 AM
Re: Engineering question about standby switches
The switch feeding into the capacitor will fail quicker than you think. For an instant, it may as well be feeding into a short circuit when the cap is empty.  
I used to work for a treadmill manufacturer, and we had a relay feeding a rectifier that fed a capacitor. It was line 120VAC, and 220uF of cap. I measured the surge current into the cap, and depending on the point of the sine wave where the switch closed, the surge could go as high as 120A!! Scale back for tube circuit values, and it is still ugly.  
I also tried this on a Dynaco ST-70 stereo amp, and the switch got blasted pretty quick. I changed the setup.  

tommy I realized something after I wrote ... -- 9/28/2000 12:37 PM