Relay newbie question

[leonc]

I've built a couple dozen amps at this point, but have not yet worked with relays, channel-switching and so on. I believe Doug's 5V relay circuit will work for what I'm building now, but I'm posting this thread to verify that assumption.


In this design, I have a switchable boost that essentially changes how the first preamp stage is biased. I have it so it works with a switch on the face plate, and as all the leads are so short, it's works great, no issue. But I'd like this function to be foot-switchable as well, but I'm sure that using a 10' long passive guitar cable/footswitch setup will just not work, I'm sure the capacitance of the cable will kill all the high end and probably other parts of the signal I don't want to lose. So I assume relay/switch would have to be the right way to go. The amp has a 6.3VAC heater line off the center-tapped PT available, no prob. The 5V relay setup (with the full bridge rectifier) will get this job done, yes?

[shooter]

You're correct, maybe, probably.  just use the relay contacts in place of the switch contacts.  Don't think it matters but I'd  run the relay ground to an from the footswitch, that way if the cord gets smashed it's not shorting your 6.3v.

[alerich]

I have an amp that already has 6.3V DC heaters for the first two preamp tubes. I use a 5VDC solid state relay to activate a solo boost function on the amp. I power the relay with the DC heater supply. The circuit uses the normally closed contacts when idle and only draws current when I activate it to open the contacts and engage the boost. I have the switching or "coil" portion of the relay that is DC heater supply powered running to a jack on the front panel. I typically use a 10' guitar cord and a BOSS FS-5L footswitch to activate it. It works great and I have not had any issues with it negatively impacting the heater supply. I have measured the heater voltage with the circuit on and off and as the relay draws far less current than a preamp tube heater it has minimal impact when it is on.

Go for it.

 

[leonc]

Cool. Thanks gents. I'll be moving forward on this within a few weeks. Alerich - that sounds exactly like what I plan to do.

[tubenit]

Leon,

There's a lot of information about relay switching along with photos, schematics, diagrams, etc.........   here:

http://el34world.com/Forum/index.php?topic=14348.0

With respect, Tubenit