285v dc on front panel miniature toggle switch

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Ecs787s

Active member
Joined
Jan 1, 2013
Messages
25
Hey Guys, I'm working on a UA176 right now and am wondering if there is any problems with using a mini DPDT toggle switch to select between two different ratios (instead of the original 4 ratio settings on a rotary switch). This switch feeds the two sidechain capacitors, so only ac will be brought to the 6al5 rectifier tube after those caps.

I assume the dc doesn't have any current flowing through the switch because of the blocking capacitors, so it just sits there. I assume that most switches are really rated for Power (wattage) and not just voltage or amperage? The wattage is what would melt it right?

Can anybody comment on this regarding safety or weather that switch will have any issues in the future?

I have already built one of these in this fashion and haven't had any problems but want to know whether I should change things around on the second build.
 
As for whether there's any DC on the switch, this should be easy to test by powering the device up and testing the leads you intend to switch with a volt meter.

Switches are rated for volts and amps, indeed. Power is derived from volts and amps (W=VA), where watts = volts x amps. Volts certainly matter too, since exceeding the rated voltage could lead to arcing across the contacts!

I can't comment on the 176, except to say please be careful when dealing with high voltage. You're asking very basic questions, and I must admit I'm concerned that you should study up on the basics before tackling any mods to a tube circuit. Please be careful.

Perhaps ask the question in the DIY 176 thread? Several members posting there seem to understand the circuit well. Good luck, and stay safe.
 
Thanks for your reply. Yes, there is definitely 285v on that switch for sure... but I guess what I was asking was since the current DC doesn't really do anything and current doesn't flow from the switch, I figured there wouldn't be an issue because this is how the UA 176 was set up back in the day. What I think I will do is put blocking capacitors before the switch that way only ac makes it to the switch. I'm talking about C6 and C7 here... I would have to use two caps per ratio setting instead of just two caps for all ratios as in the original schematic....

Thanks and I appreciate the safety talk, cause it is definitely some extreme voltage!
 

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