Implementing a relay in a hand-wired amp

[hamfist]

I'm in the process of trying to implement a relay for channel switching in my hand-wired amp.
Now, pretty much all the appropriate relays I've seen are designed for PCB.
I'm interested in gutshots of how others have sited and firmly fixed relays in their amps.

At the moment, I've just used some silicon to stick it down (the back of the relay stuck to the inside of the chassis). The PCB pins are sticking up at me, and I have simply soldered each wired straight to the pins. However, the pins are pretty small and fragile, and the leads leading in/out of the relay are quite long and heavy. I am concerned about fatigue in those joints, what with all the weight of the long leads flapping around inside.
The very natue of what we use relays for often will mean that there are long leads going to it. It seems almost impossible to avoid
I've tried to secure these leads as best I can but I'm not convinced I've done a great job of it. I think I may need to secure them near the relay as well, maybe with some silicon holding them to the chassis wall.

So how do some of you guys do it ?

[Enzo]

They make plenty relays with solder lugs, but they are a lot larger than the little PC types. I often glue them to the circuit board legs up and run jumpers down to the board. Nothing says you can't take a wire from each leg and glue it to the chassis or otherwise anchor it. Are you using like #18 wire? DOn;t need to. Smaller wire has less mass and will flop around less. Use like #26 or something small and solder on, then draw down alongside the relay and glue it right to the body. The loose half inch of wire won't be flapping very much.

Circuit boards are a convenient way to connect spindly legged little parts to wires.

Radio Shack stock 276-159 sells for $2.49. (And they have others) It snaps into two. Park a pc relay in the middle and run wires to the pads as appropriate. There is space for the diode across the relay coil and even a resistor or something if needed. Or maybe a small part or two to implement a power supply for it. You can use the holes in the corners for mounting or get creative.



One I use a lot is this one, 276-170 at $3.49. The foil is on the reverse side in this picture. The holes and foil patterns are exactly the same as their wireless breadboard. If you dummy up a circuit on the breadboard and it works, you can transfer the parts over to this board in the same pattern and solder it together. You could mount several relays end to end on it for example. Whe I need just a single IC or something, I cut off a piece and save the remainder for another project.



Your amp may be hand wired, but it won't hurt your rep to use a small board to mount a relay.

[hamfist]

Haha, I don't think I have a "rep" yet, apart from being a bit of an amp-doofus !

THanks for the ideas and advice Enzo.

Due to the layout of my amp, and the nature of what I'm doing, I'm having to have reasonably long wire lengths internally. For this reason, I'm actually using shielded cable for all the inputs/outputs of the relay (not the power, obviously). I have a lot of shielded cable in this amp and it has paid dividends as I have a very low noise floor (looks a bit of a mess inside, but I love the quiet between notes !). BUT, the big issue is that the shielded cable is heavy and can flop around if not secured.

I've just put in an order for a couple of small terminal strips, which I intend to put close up to the relay on either side. I'll then run the shielded cable to the terminal strips and then the very short run from the terminal strip to the relay. Should be a pretty good long-term solution I think. It won't be pretty, but it'll be effective I think.

[Enzo]

Well, give 276-159 consideration. Relay will drop in the holes, your cAbles would solder to the surrounding pads. Tie wrap the cables in a bundle. Stick the thing anywhere. When you have like half a dozen conductors all grouped in a bundle, they don;t move relative to one another very much, which is what they'd have to do to break off the board.

[Steve Conner]

I used similar little boards to mount relays in my amps.

In my last build I actually used some relays that I salvaged from an old broadcast TV camera controller, and they were already mounted on pieces of that stuff. You probably don't get those exact Radio Shack boards in the UK, but Maplin have something similar.

[hamfist]

This is how I did it in the end. The relay was superglued and siliconed to the chassis, in a convenient spot. All the shielded wires leading to and from the relay were secured to the chassis using two small pieces of aluminium (superglued to the chassis) and more silicone.