wiring 9vdc relay

[Anonymous]

Being electronically challenged, I need help. I have a 9 vdc Radio Shack mini relay for a background sound project. Does anyone have a basic diagram on how to wire a relay?? It has 5 prongs--1 common, 1 NO, 1 NC, and 2 for coil. I cannot figure out what goes where. Thanks.

[Jacktal]

A relay is in fact an electrically activated switch.Most times it is used to power high amperage accessories with a very small swich as the relay does handle the heavy load through its secondary circuit.The power supply comes through the "Common" terminal and comes out the "NC"(Normally closed) terminal all the time the relay is not actuated.When you actuate the relay,the NC terminal becomes unpowered and then the power goes through the "Common" terminal to the "NO"(Normally open) terminal which is then powered.

This feature allows to either power or unpower different accessories,or both simultaneously, upon activation of the relay by applying power(9VDC in your case) to the coil terminals.Unless specified,polarity of current applied to the coil doesn't matter but voltage does.

A relay has two independant circuits,the primary(coil) that activates it and the secondary that handles the current from another source to any accessory you wi***o operate.The source may have a different voltage,even be AC,as long as the rated capacity of the relay isn't exceeeded.

[Anonymous]

QUOTE: Originally posted by elkman

Being electronically challenged, I need help. I have a 9 vdc Radio Shack mini relay for a background sound project. Does anyone have a basic diagram on how to wire a relay?? It has 5 prongs--1 common, 1 NO, 1 NC, and 2 for coil. I cannot figure out what goes where. Thanks.

elkman,

Sounds like you have a SPDT (Single Pole Double Throw) relay.

1) To energize the coil and throw the switch (relay), connect DC power to the 2 coil connections (the electro-magnet). Polarity shouldn't matter.

The other three connections are for the circuit you want the relay to control. (This circuit is independant of the coil and may be AC or DC and of a different voltage and/or amperage than the coil):

2) If the coil is not energized, an internal spring in the relay will keep the switch set for the NC (Normally Closed) path. This will be between the common connection and the NC connection.

3) If the coil is energized, the electromagnet created by the electrical current running through the coil will overcome the internal spring and throw the switch (relay) to the NO (Normally Open) path. This will be between the common connection and the NO connection. When the coil is de-energized, the internal spring will return the switch (relay) to the NC path.

If your unsure, you can always use a battery and a small low-voltage lightbulb to the relay to see which connections you have a circuit for, and which you do not. Then energize the coil and test again, de-energize the coil and test again. The bulb will light whenever you have a circuit through the relay.

Hope this helps.

Dale B.

[Anonymous]

Thanks for the help. Intend to experiment today. Radio Shacks 20 sec. sound module works great in trackside industries, just needed continuous running. Plans on internet show a relay to make it continuous. Am learning as I go.