what type of relay/transistor should I use for a 9v 9 mA piezo transducer??

I need to know asap for school!!

framistan7 years ago
USUALLY a relay or transistor is used as a SWITCH. Just like in your CAR. when you turn your car key, ---that is a TINY little switch that turns on a BIG relay. The big relay can handle the MANY AMPERES, but the little KEYSWITCH can not. So, unless you have a reason to use a relay or switch in the circuit, I would say you just need a PUSHBUTTON... no relay, no transistor. If you insist on using a transistor, I would go with a very SMALL one like a 2n3904 type. The reason is because the piezo only uses 9 milliamperes. that is only point zero zero nine amperes. so no relay is needed. If you insist on a relay, i would use a SMALL relay called a REED relay. they are availab e in various voltages. FRAMISTAN