Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: JustMike on May 18, 2011, 07:56:35 am

Title: Building a relay switching circuit
Post by: JustMike on May 18, 2011, 07:56:35 am

 I want to put a simple "solo boost" ckt in my Home built JCM-800. I robbed a circuit from a Silver Jubilee for the heater rectification. It works, but I think I need to reference ground somewhere in the circuit because there is hum and when I touch the footswitch with my bare hand, the hum goes away.

(http://www.ceriatone.com/images/layoutPic/marshallLayout/2555.jpg)

I built the little daughterboard on the right side of the diagram and I'm using a Rat Shack solid state relay. Like I said, it works, but there's no reference to ground. The neg. side of the caps ties to htr B+, so that's not it.

Title: Re: Building a relay switching circuit
Post by: Geezer on May 18, 2011, 11:46:25 am

Is your footswitch jack isolated from ground/chassis?
If yes, then try (temp using clip leads) a 47R or 100R resistor (whatever close you have) from the "sleeve" terminal to the chassis....does that help?

G

Title: Re: Building a relay switching circuit
Post by: JustMike on May 18, 2011, 07:01:45 pm

OK, I got it working. Of course, it was a wiring problem. Now, the issue is that with no switch plugged into the jack, the LED is on. And I believe that's just the way this simple circuit is. Of course, with the LED on,the boost ckt. is activated. But I want it by default to be off.


  Wait a minute, it's a Cliff jack. So I can wire the jack to be shorted when nothing is plugged in, right? That would do it. (I think).

 (edit) No, I don't think so. OK, now I'm confused...help.

Title: Re: Building a relay switching circuit
Post by: TIMBO on May 18, 2011, 10:56:15 pm

Thanks to Geezer this is how the Silver Jubilee relay circuit ended up, because i got caught out with the LED being on when the switch is off and relay off. This way every thing is ON when turned ON

Title: Re: Building a relay switching circuit
Post by: Willabe on May 19, 2011, 01:07:22 am

Quote from: JustMike on May 18, 2011, 07:01:45 pm

OK, I got it working.

Yes, but how. What did you do/change?


          Brad           :icon_biggrin:

Title: Re: Building a relay switching circuit
Post by: TIMBO on May 19, 2011, 02:21:23 am

This is the original

Title: Re: Building a relay switching circuit
Post by: JustMike on May 21, 2011, 11:57:43 am

Thanks all. I got it working.