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CDM1250 as a station alerting base

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RT145
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CDM1250 as a station alerting base

Postby RT145 » Fri Nov 04, 2016 6:13 am

I'm currently building a station alerting system for our firehouse and its going to be pretty much a carbon copy of this design: http://www.rayvaughan.com/recall.htm

The only thing I'm not 100% on and it doesnt seem to touch on in the schematics, where do the pins from the CDM attach on the relay and timer? I assume that based on the screenshots and schematic that pins 3 & 4 go to 3 & 6 on the relay and 8 & 14 go to 6 & 5 on the timer, however I'm not 100% sure which one goes where. Does anyone have any insight?

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jackhackett
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Re: CDM1250 as a station alerting base

Postby jackhackett » Sat Nov 05, 2016 8:44 am

It looks like pins 3 & 6 on the left relay are for audio from the radio. The text states that it is balanced audio so they probably used the CDM speaker outputs, pins 1 & 16. If you're driving a PA amplifier that isn't balanced input or you are not sure, you should use an audio isolation transformer.

Pins 5 & 6 on the timer go to a switch closure to trigger the timer. On the CDM this would probably be pin 4 (Ext Alarm Output) and pin 7 (ground). I'm not sure which way they connect though, if you wanted to be safe you could use a small 12V relay with it's coil connected to accessory pin 4 and +12V, and then use the contacts from that to trigger the timer.

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SteveC0625
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What radios do you own?: CDM's, CP's, CM's, and more

Re: CDM1250 as a station alerting base

Postby SteveC0625 » Sat Nov 05, 2016 8:50 am

RT145 wrote:I'm currently building a station alerting system for our firehouse and its going to be pretty much a carbon copy of this design: http://www.rayvaughan.com/recall.htm

The only thing I'm not 100% on and it doesnt seem to touch on in the schematics, where do the pins from the CDM attach on the relay and timer? I assume that based on the screenshots and schematic that pins 3 & 4 go to 3 & 6 on the relay and 8 & 14 go to 6 & 5 on the timer, however I'm not 100% sure which one goes where. Does anyone have any insight?

Post #17 in this thread has a schematic showing the pins to use on the CDM for what you want. His design is much different, but the pin-outs for the radio are the same. http://forums.radioreference.com/indust ... ystem.html

On the Radio, pins #1 and #16 are audio out. You may or may not need a matching transformer. DO NOT GROUND either of these pins - you will kill the audio amp in the radio. Plenty of detail on that for the easy searching here and on RR.

CDM1250 pin #13 is Switched B+ and Pin #4 is the Alarm Output which is programmed to go low when the alarm is activated.

Check Ebay seller mre1032. He sells little kits with the 16 or 20 pin accessory connector and wires with the pins already crimped on. He is well respected in the Motorola hobby community and beyond. I keep a stock of his stuff here for installs.

RT145
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Re: CDM1250 as a station alerting base

Postby RT145 » Sat Nov 05, 2016 9:27 am

As luck would have it I actually just purchased one of the connector kits from mre1032. Our existing CDM has a connector but only one pin for the ignition sense pin.

So just to make sure I have it correct, does the pin programming shown in this picture have any correlation to what pins I have to use for which part?
http://www.rayvaughan.com/images/projec ... ecall2.jpg

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jackhackett
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Re: CDM1250 as a station alerting base

Postby jackhackett » Sun Nov 06, 2016 5:06 am

RT145 wrote:So just to make sure I have it correct, does the pin programming shown in this picture have any correlation to what pins I have to use for which part?


Other than pin 4, external alarm out, no.

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SteveC0625
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What radios do you own?: CDM's, CP's, CM's, and more

Re: CDM1250 as a station alerting base

Postby SteveC0625 » Sun Nov 06, 2016 6:17 am

RT145 wrote:So just to make sure I have it correct, does the pin programming shown in this picture have any correlation to what pins I have to use for which part?

I thought I clearly answered that in my earlier post.

Pins #1 and #16 are audio out. They are not on the list of programmable pins that you posted in a screen shot and therefore are not programmable.

Pin #13 is B+ and is also not on the list of programmable pins and is also not programmable.

As I said in my previous post, Pin #4 has to be programmed to go Low when activated. It does show in the list of programmable pins and therefore it must be programmed as such.

You can look on the batlabs.com reference pages for the complete info on the accessory connector for the CDM's. It's been there for over a dozen years, and the info is still correct.

RT145
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Re: CDM1250 as a station alerting base

Postby RT145 » Sun Nov 06, 2016 12:30 pm

My apologies, I just wanted to make sure I was understanding it correctly.

RT145
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Re: CDM1250 as a station alerting base

Postby RT145 » Fri Nov 18, 2016 11:44 am

So I wired it up but I can't get the radio to trip the system. When I initially hook up the wires the tone generator will go off, but not when I set the tones off on the radio frequency. I put a voltmeter on pin 4 and it shows voltage when the tones drop, pin 13 seems to show constant voltage. I've tried reversing the wires and that doesn't help. Any thoughts?

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jackhackett
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Re: CDM1250 as a station alerting base

Postby jackhackett » Sun Nov 20, 2016 7:46 am

What model timer are you using?

Pin 4 should have around 12-14V on it. When the radio receives the correct tones the voltage should drop to around a volt or so for 2 seconds (if you programmed the radio like the pictures in the article show).

Use the radio to trigger a 12V relay (Bosch/Tyco automotive type, max coil current <200mA). Connect the relay coil to pins 4 & 13 of the Acc. connector. If the relay has a built in diode you have to make sure pin 13 goes to the cathode side of the diode. Then connect the normally open contacts of the relay to the timer pins 5 & 6. When the radio receives the tones you should hear the relay active for 2 seconds, and the timer should start.


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