Alternatives for relays?

[Tirefryr 1,742]

I remember reading about this somewhere, but I can no longer find the information. I'm wondering if any of the EEs we have can give me some insight as to the benefits other than cost and how to implement them into my system. This will mainly be used for control of alarm accessory channels. Thanks!

[ANeonRider 3]

I think what you read before is in this thread:

http://www.soundsolutionsaudio.com/forum/i...?showtopic=4685

[Tirefryr 1,742]

No, it wasn't on a forum. I'd come across an article somewhere. Can you go into detail for me, or is it even feasible?

Cheapest I'm finding any SPDT relays for is $2.99 and that's for cheap ones. I don't like cheap relays. Bad luck with them.

[///M5 2,833]

What is wrong with a non-cheap relay?

[Tirefryr 1,742]

What is wrong with a non-cheap relay?

It's not cheap. I haven't been able to find a good quality one for less than $6. Personally, I think that's a little on the high side, then add into the fact that they are rather bulky in comparison. Trying to keep this as cheap as possible.

[Supa_c 1]

junk yard ?

[Tirefryr 1,742]

Nope. New, not used. I have a bungh of Potter&Brumfield 24V relays, but they're over 3" tall once plugged into the socket.

[Supa_c 1]

Tad large.

[///M5 2,833]

Big 'uns

[thch 0]

transistors can be used. each device has a different benefit or flaw.

Relay = slow switching, allows current in both directions, requires current to the coil

FET = fast switching, current pretty much in 1 direction (not entirely true), no need for current to control the device

BJT = fast switcing, current in 1 direction only, small contol current.

SRC/TRIAC = application specific. for DC the issue is that they don't turn off...

A PFET would be the best alternative to a relay. applying a voltage to the gate would cause the FET to turn off. removing the voltage at the gate would cause the FET to turn on. has a few milliohms of impedance through the device. probably should not go over 50A with a single device.

NFETs would also work, but you'd have a 2V or so drop across the device, limiting current to under 10A.