Electronics... Anyone know thier stuff?

[MsDG]

I knew some advice on circuit over current protection....

I am creating a simple 5v relay circuit, incorporating several 5v relays, several micro switches - powered by a 5v low current DC power adapter knicked from a usb hub.

The circuit is simple...

5V+
wired to micro switch,
micro switch wired to 5v relay
obviously the otherside of relay will be wired to 5v-

I will have several of these running in paralle

My question... will i need some kind of over current protection on this circuit... and if so, what?

[Carterman]

I'm presuming the power supply is just powering the coils of the relay??

If so you need to fathom out the total current draw of all 5 relays as if they were all on at once, compare this to the supply. If they are below the supply rating then all is good. If not, find a more hefty supply.

The relays should be switching something other than their own supply....

Hope this makes sense!


EDIT.. Forgot to mention that the power supply will no doubt have its own current protection built in... Overload it and it should cut out....
Mike.

[MsDG]

That's brilliant... thanks

[Eazi]

On the circuit side, if you are trying to protect the supply, placing a 5v zener diode accross the supply legs will prevent surges as the relays operate..

http://en.wikipedia.org/wiki/Zener_diode

[braymond]

you need a diode across the supply pins of each of your relays to stop back emf
in4148 will do