Elk Dry Contact relay

Hi,

I need to control some items that require dry contact relays. My elk appears to only have output voltage capabilities (unles I'm missing something) onboard. I need 6 relays.

Will the ELK-M1RB work for this? Or is there another option? Is there a cheaper option?

Thanks,
W

english_1969 said:

Will the ELK-M1RB work for this? Or is there another option? Is there a cheaper option?

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Don't know about cheaper, but the M1RB is a solid choice. Plugs right in to the M1, cable included.

The M1RB has transistor drivers on board to switch the relays properly. Driving an individual relay coil directly from Output 7 to 16 may or may not turn on the coil of a relay properly according to the current requirements of the relay coil.

Should you use an individual relay, make sure you put a reverse diode across the relay coil to kill the kick back transient of the coil. The reverse diode is also built into the M1RB.

Spanky - Does the Elk912 also have the reverse diode on it? Just curious, since I'll be using outputs 9-16 to drive the Elk124, and figured I may some day use the 912's to give me 2 more relay outputs in the box...

English - for your purpose, Lagerhead is right - that'll give you 2 more than you need, but it's about the price of 6 individual relays, and it's by far the cleanest solution. Otherwise, if you want to locate the relays more spread out near what they're controlling, the 912 seems to be a useful little relay - I bought a few just to have spares.

FYI, I believe in past posts Spanky recommended the 924 instead of the 912 relay as it has a lower voltage trigger threshold.

Interesting - that's a DPDT instead of an SPDT... all I needed was SPDT, so I didn't look much further. But, the fact that it only draws 1ma vs. 30ma could be important when running a bunch off the main panel. Ironically, the M1RB consumes up to 250ma, so it looks like that uses the 30ma relays. Good info though - made me look at the options a little closer.

Todd B said:

But, the fact that it only draws 1ma vs. 30ma could be important when running a bunch off the main panel.

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Without checking, I think you are confusing the "trigger current" with the "draw current". The sensitive relays may trigger with only 1 mA, but they still draw a decent amount when energized.

Well that answers my question! Thanks guys.

The ELKM1RB it is. it's not that it's that expensive, but I'm already fighting with a budget

W

english_1969 said:

but I'm already fighting with a budget

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Ha - my way around that... keep the initial order small, and tell the wife about the cost of that one... then just not tell her about the subsequent orders. As far as she knows, all our home automation and security was accomplished for under $1K!

The ELK-912 SPDT Relay does have the reverse diode built onto the PCB.

The ELK-912 draws about 40ma at 12 VDC. Outputs 7 to 16 on the M1 generally will pull the 912 relay coil in, but it is at the outputs current limit due to current limiting resistors in the drive circuit of the M1.

The ELK-924 will trigger with 1 ma of current because it has the driver transistor built in. The coil current is supplied from a separate set of 12 VDC terminals that connects to the M1's Aux power supply.