Relay Source Question

I need this relay, as cheaply as possible. Any ideas what the proper term for it is, and a source? Thanks much for your time!

I need this relay, as cheaply as possible. Any ideas what the proper term for it is, and a source? Thanks much for your time!

Ah. It's a "Double Pole Change Over" relay. Not having much luck searching for it.

It is called a DPCO, "Double Pole Change Over" relay. No luck in finding one yet.

Single Pole Double Throw = SPDT with a 9Volt coil.

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Catalog # RLY-419 from Allelectronics

It will give you an extra set of contacts, and has a better (higher resistance, 540 ohm) coil rating.

Or part number G6E-134P-ST-USDC9-ND from Digikey

if the extra contacts and higher resistance of the Allelectronics relay are objectionable, and if you want to pay a whole bunch more for the Digikey relay.

Ed

The relay in your drawing is single Pole, Single Throw (SPDT)

A "Double Pole Changeover" would more often be called "Double Pole Double Throw" (DPDT), and would have two sets of contacts.

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I think he meant "Single Pole, Double Throw (SPDT)".

--
James T. White

Geez - look in the thread, one post above. I gave you two part #'s for what you asked for - an SPST 9V 400 ohm coil relay. NOT a DPCO as you now state.

Ed

I'm pretty sure that's what I wrote - some electrons must have gone astray....

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Why are you multiple posting???

DPDT stands for Double Pole Double Throw. All DPDT relays have *two* NC positions.

Are you sure these are

You can read it for yourself. I posted the links.

No. You need to satisfy the current requirement of the relay. Adding resistance will lower the current.

However, if you use a relay with a lower voltage rating than the circuit provides, you can add resistance so that the current through the relay coil is correct. It is not necessary in this case with the relays I specified.

Ed

SOP for Google posters lately.

Bobscar

What you drew was a single coil, SPDT relay....If you need two coils, you need two relays.

Not in this case. The coil produces a magnetic flux necessary to pull the contact plate. The amount of flux needed is determined by the number of turns on the coil and the cross sectional area of the wire. The resistance of a lenght of wire is (rho)L/A, where rho is a constant that depends on the metal of the wire. If you add more resistance in series to a relay coil, you will reduce the current. This will in turn reduce the amount of magnetic force which will not allow the relay to operate. Also, it depends...what else is in the ckt of the coil? If you use a coil with less resistance, you need to make sure that the circuit driving the relay coil can support or supply the additional current.