Relays and how do you use them

[Ed_Chambley]

Seems relay boards are a popular topic right now.  I have used them for simple things like channel switching.  I was just wondering what others have used them for?  Like to have some input as I really never considered all the possibilities available with the use of relays.

[tubenit]

My starting place to ponder their use is what can I do to parallel or place in series with a cap or resistor? And in use of making or breaking a connection Some examples might be:

PAB - break between treble and bass pot
PAB - added resistor to ground below a mid pot
mid boost- parallel a 500p & 500p  or put in series a .002 & 500p
fat - engaging a second triode to parallel triodes
fat - parallel a cap and resistor on a cathode
bright cap -  like a 120p on a volume pot
PAB & chime tone stack switching -   like on the TOS 2CF  (look it up)
clean to OD channel switching
OD trim boost -  switch a resistor between trim pot and ground
LNFB  -  in/out local negative feed back
NFB - in/out negative feedback
slope resistor  -  you could put resistors in series to have 33k (normal) & 47k =  
                         81k slope
bypass a tone stack
lift a tone stack
have a switchable cut control
Geezer's  psuedo channel switching -  switches from one pot to another
                                                       to simulate channel switching
switch a paralleled resistor across the outside lugs of a pot to lower pot value
switch a reverb or tremolo on/off
switch an active effects loop  on/off
switch high frequencies to ground   (like a 250p in series with 470k to ground)
a "psuedo PPIMV switch"  by having 100k grid resistors in series with 120k grid
                                      resistors
tone stack cap switching  like taking a .047 mid cap and place another .047 mid
                                     cap in series

Some of these might not be useful on the "fly" but could easily be done between
songs.

There are other uses but this covers some that I've experimented with or thought about.

With respect, Tubenit

[tubenit]

These schematic switches are mentioned in the post above. See if you can match the description with the schematic component.

Tubenit

[Ed_Chambley]

These schematic switches are mentioned in the post above. See if you can match the description with the schematic component.

Tubenit

Some great ideas here.  Some of these actually make a completely different amp circuit.  Some food for thought.  I really like the cut on a relay added to channel switching.  Thanks for the input.  A lot of these I have done with toggles.............so I have not considered changing the circuit and design with one switch.  It really is a different way of thinking.

[Stankfut]

Just curious: as ed says a lot of the switching you mentioned can be done with toggles, so what is the advantage of a relay?

[Geezer]

Just curious: as ed says a lot of the switching you mentioned can be done with toggles, so what is the advantage of a relay?

Live performance ability to instantly change multiple circuits while still playing your guitar....with the stomp of a button with your foot instead of stopping, turning around to your amp and flipping one or several switches, then trying to remember where in the song you are......then flipping them all back again for the next section of the song.

If you never play live, and don't mind stopping to change a bunch of switches, then relays are not needed at all.
But for live performance (or even just for convenience whilst practicing/playing at home) relays are a must for me.

G

[Stankfut]

Geezer, thanks for the answer, but I realize I didn't ask the right question 

I understand the benefit of a relay in channel switching, but two things in Tubenit's post puzzle me, first he said some of the functions may not be useful "on the fly", but could be done between songs. I can see adding a relay in this case if you are simultaneously switching two or more circuits, but is there an advantage to, say, simply disconnecting NFB or some other simple function?

The other thing he mentioned was to turn on/off reverb or trem. Why not just use a switching jack and a footswitch? Fender has been doing that for years, and it works pretty good. Is there an advantage to using a rely here?

Please bear with me....still trying to learn

[PRR]

> what is the advantage of a relay?

"instantly change multiple circuits.."

Also, change things at a distance.

Killing reverb, bah. As you say, run the signal out where you can short it.

Some "clean/lead" schemes switch MANY things. Preamp gain, extra stages, tone/EQ, reverb level and tone, flux-caps.....

You may not have a 13-pole finger-switch.

You might not be able to bring all those signal onto one switch without intolerable sneakage, leakage, and oscillation.

Some things may be far away from where the switch should be. Routing a wire all over the chassis invites treble-suck and contamination.

Yes, many fine amps don't use relays. They are for tricky-stuff.

[tubenit]

The other thing he mentioned was to turn on/off reverb or trem. Why not just use a switching jack and a footswitch?

I wouldn't use a relay for reverb or tremolo. A traditional ft switch that shorts the signal would work just fine.  I was simply listing ideas and that was just one of 19 possibilities.

PRR's comment about a relay switching numerous things is an excellent point. Geezer (genius that he is,IMO) does that with his psuedo channel switching that switching several pots in and out simultaneously.

This forum has some remarkably creative ideas and thinking on it, so I hope others will post more thoughts on how relays could be used.
 

with respect, Tubenit

[kagliostro]

The list posted by Tubenit is very large and I think complete

however, give a look to this post, you can find some particular use of relays that can be interest to know

they are intended for uses different from amps, but also in amps you can find situations that can have benefit using one of this solutions, like the Constant to Momentary Output as an example

http://www.el34world.com/Forum/index.php?topic=14407.0

K

[tubenit]

they are intended for uses different from amps

Some very interesting and creative ideas.

With respect, Tubenit

[EL34]

so what is the advantage of a relay?

As the guys said above

One footswitch can activate 4 relays at the same time
That's the same as flipping 8 SPST toggles switches one at a time

[Stankfut]

sorry if I seem dense....its only because I am This is uncharted territory for me....so it's taking a while to get my head around it. There are some great ideas mentioned and I am eager to try some, time and finances permitting.

[EL34]

see this post

http://www.el34world.com/Forum/index.php?topic=14598.new#new