Thread: usb cutoff switch

your connection methodology is correct, but i don't think it will work at all then. most typical audio signals are around 0.5v in amplitude. with the relay dropping 1.5v between the input and the output terminals, i don't think the signal will ever make it out of the relay..

I'm a little lost with that. What does the voltage coming from the battery (source) being dropped by 1.5 have to do with the audio signal passing through the closed circuit? Or am I reading it wrong?

sorry, it's the other way around.

solid state relays are literally a very large transistor.

the easiest way is to first explain how a transistor works-- http://www.satcure-focus.com/tutor/page4.htm

i believe this is the most applicable line:

Imagine a pool of water near the edge of a table. It rests there with surface tension holding it in place. Now put one tiny drop of water on the table edge and let it touch the pool of water. Suddenly, the pool drains onto the floor as gravity takes over! Your tiny drop provided the catalyst to get it moving. So the base electrons do a similar job for the "pool" of electrons in the emitter - helped by the "gravity suction" of the power supply voltage on the collector.

now what lacks in these definitions is how some of the voltage is getting lost to turn the circuit on.


and because that amazon link is so hard to read with everything thrown together, here the mfg's site with everything in nice little chart:
http://www.opto22.com/site/pr_detail...=4&item=DC60S3

the specs show 2 different voltage drop figures. 'forward voltage drop' and 'signal dropout voltage'

'forward voltage drop' is referring to the amount of voltage that is 'lost'(voltage can never just disappear-- this 1.5v is converted to heat due to the way the relay is made) going from terminals 3-4--the wires that interrupt the audio circuit.

'signal dropout voltage' is referring to the amount of voltage that is being 'lost' from terminals 1-2--the wires that activate the relay.

both figures are at or above 1v loss. for a audio application like that, the loss is nearly double of what the expected source voltage will be..

I guess I'm out of luck b/c all the relays by them seem to do the same thing. Is this a common thing with solid state relays, or just their products?

i assume it would be common across all solid state relays, as they are all made very similar..

you can always try some smaller relays-- being that you really only need 0.5A or so of current-carrying capacity..