Relay channel switching Pop & EM field from coil

[Willabe]

Do I need to add a 1M on each of pins 2&7 to ground (and take out the single 1M), to keep this from poping when switched?

Or will the 1M that's already there, since it's on the common, work?

Also how close can you put a 5v relay to the input jack? Schemo #2 shows the PSU (Dougs) I'm going to use, which should be very quite with the 2@ 4700uF caps and a FWB, the relay only draws 40mA. I need to put the relay with in an 1" of the input jack.


                        Brad        

[navdave]

Try adding a 1M resistor after each 34k resister to ground.
I really don't understand the purpose of switching from one
side of the tube to the other? If it's for a tone change you would
need to use something like a .68uf or 1uf on the other side of the triode for a treble boost.

[sluckey]

Have you considered an AB/Y footswitch?

[Willabe]

Have you considered an AB/Y footswitch?

Yes, that's the usual way guys do it for a 5G9/5E3 pre. But I thought since I'm building this from scratch, I'd put the relay in and get rid of 2 the extra cords.

I'm thinking since it's the current and not the voltage that would cause a problem, at 40mA it should be fine?  


                           Brad        

[navdave]

Put the relay on your main board as close to v1 as you can.
Use shielded cable to get you guitar signal from input to relay
then back to the two tube grids.

Also how close can you put a 5v relay to the input jack? Schemo #2 shows the PSU (Dougs) I'm going to use, which should be very quite with the 2@ 4700uF caps and a FWB, the relay only draws 40mA. I need to put the relay with in an 1" of the input jack.


                        Brad        

[The_Gaz]

Willabe, I've been down this path before, and if I were you I'd put the relay after V1 before the 100K mix resistors and use it to short either channel. It's still a very sensitive area, but it'll be less prone to injecting noise into the grids than the input because the signal to noise ratio will be much better. Like I said this area is still very prone to noise, and don't be suprised if running the relay supply from the heaters gives you troubles. What I've done is used a cheap 6.3V transformer, and rectified that to power the relays. I then like to regulate that with a little LM7805. Here's a link to the transformer. Only 200mA, which is about 100mA when rectified. Not a lot of current, but more than enough for a high sensitivity relay, which pulls about 30mA (make sure to check the datasheet on yours). for $3 more they have a 1A version as well.

[EL34]

I had no problems running the relay power supply off the 6.3v heaters

This diagram is the one that I used on several projects and it works great


The relay power supply board is over near the power tranny


Here it is in a stout reverb



The 5 pages of relay switching info on the library page is here
http://www.el34world.com/projects/relay_switch.htm