Roff
Well-Known Member
This is in respose to Tickled Pink's question about relays in the General forum.
A relay is basically a mechanical switch, controlled by an electromagnet. Picking one on short notice is tough. I see one in the Jameco catalog, their p/n 187240CP, that appeals to me because it is small and only requires 30ma to activate it. It is probably not the best, but it would probably work.
If you use a higher current relay, you should use a lower value for R1.
The diode protects the transistor from the flyback pulse that would otherwise occur when the relay turns off.
A relay is basically a mechanical switch, controlled by an electromagnet. Picking one on short notice is tough. I see one in the Jameco catalog, their p/n 187240CP, that appeals to me because it is small and only requires 30ma to activate it. It is probably not the best, but it would probably work.
If you use a higher current relay, you should use a lower value for R1.
The diode protects the transistor from the flyback pulse that would otherwise occur when the relay turns off.