Need some guidance in wiring up relays, please.

[ubersam]

I am designing a circuit where I need to switch four contacts simultaneously. Because there seems to be a scarcity of 4PDT footswitches, I started looking into relays. I have read up what I could find re: using relays and I've drawn up some ideas of how I think the relays should be wired up. I am aiming for the best click/pop/thump performance, using a mechanical switch to activate the coils, and I think that option A or B would give me that, maybe a combination of the two. I'm not sure about option c. So, could someone let me know if I am going in the right direction with this?

[oldrocker]

I will be watching this thread.  Would adding a pull down resistor in this bypass pedal help with clicks and pops?  What does the cap do?
Can I add this to my circuit?  Sorry I'm not much help here.  I have a Strato Blaster as a buffer in this bypass pedal.  I used three 9 volt relays pictured below.  Also the circuit and a pic of the bypass pedal.
http://www.logmonster.com/images/full/?pic=Passthrough_1155588965-422-13155.jpg
http://www.logmonster.com/images/full/?pic=pRS1C_2110707w345_1155462600-422-13146.jpg
http://www.logmonster.com/images/full/?pic=Pass_1155507154-422-13147.jpg

[Transmogrifox]

This may give you some ideas using latching relays:
www.geocities.com/transmogrifox/relay

I prefer latching relays because they don't require so much continuous juice to operate.  The NEC relays I have specified are particularly low power.

Your ideas above are moving in the right direction.  A and B are about the best, while D would be optimal if you got rid of the resistor to ground....as long as you use a resistor that can handle the power dissipation.  If you get two 5V relays you can usually wire the coils in series and operate them as low as 7 volts like that.  Most 5V relays will snap at 3-4 volts.  One last thing you'd add to your diagrams is a diode in parallel with the relay coil to dissipate inductive flyback when the relay was switched off. I wouldn't recommend a non-latching relay if you intend to use a battery as your primary source of power.

[R.G.]

Relays click for two reasons:
1. like the mechanical switches they are, they will click when connecting two circuits which would each prefer a different DC level
2. the coil switching voltage may be capacitively coupled into the signal line. This is worst when the signal line is high impedance, as it is when opening a line into an amp.

To avoid 1., make sure your connections on each side of the relay switch contacts are at the same DC level before and after you switch. This usually means a capacitor into and out of the relay if there is not already one on the circuits being connected, and a pulldown resistor to keep those caps at 0Vdc when the relay contact is open.

To avoid 2., slow down the rate of change of the coil voltage when you switch the coil. Mechanical switches to control the coil are worst for this because the switching is both instantaneous and bounces, making several clicks if it makes any. Most setups will put a BFC right across the coil contacts to slow down the rate of change of the coil voltage. If you driver it with a semiconductor driver, slow down the semiconductor so the relay coil voltage changes over about 50mS.

You can read about audio uses of relays at GEO. That might help.

[Dragonfly]

heres some basic relay info as well...though Trans and RG cover things well...this is more for anyone looking for a basic tutorial...

http://www.uoguelph.ca/~antoon/gadgets/relays/relays.html