2 Tone Gate Relay

[New2radios]

Hi,

The radios we use at work operate our electronic gates. From what I'v heard they operate via 2 tone?, but can someone please explain how this features works? How can a radio control a gate? Can you also program a radio to open/close a garage door?

 

[WA0CBW]

You key your radio and send a 2 tone signal. The radio at the gate receives the transmission and decodes the 2 tones and causes the radio to output a signal to trip a relay. The relay is connected to the gate open/close switch. The same thing could be done with a garage door.

 

[New2radios]

You key your radio and send a 2 tone signal. The radio at the gate receives the transmission and decodes the 2 tones and causes the radio to output a signal to trip a relay. The relay is connected to the gate open/close switch. The same thing could be done with a garage door.

Can you set this up to remote access pretty much any power device? If I'm setting this up do I keep the ground connected on the device and connect the positive lead to the device? What's the voltage or max amp sent from the mobile radio?

Could I use mdc or 5 tone instead?
Do you need dtmf options?
On the Mobil radio you are using decode or encode?

 

[WA0CBW]

It depends on the output of the radio. It would most likely be either a high or a low output and would sink or source only a few milliamps thus the need for the interface relay. Look at the radio programing to see how/which pins on the radio can be programed for detecting the proper 2 tone code and what is their voltage/current rating . The contacts on the relay would be chosen to handle the voltage and current rating of the device to be controlled.
Any signalling method can be used depending on the radio. You would need a radio that would encode the signaling and a receiving radio that would decode the signaling.
BB

 

[WA0CBW]

Additional information: There are several companies that have DTMF decoders that you hook up to the audio output of the radio to decode the DTMF tones and trigger a relay or multiple relays with different DTMF tones. This might be easier than building an interface to the radio accessory pins. Lookup DSchmidt Technologies. We use them for all kinds of things at our shop.
BB

 

[New2radios]

Thanks for the info: I want to use a Kenwood TK-8180 that we have as the receiver. I was thinking about using the ground to trigger instead of the positive since I don't think I can't get out the correct voltage from the back of the mobile radio. I think the max is 5v and would need 12v to trigger the device.

 

[mmckenna]

On the TK-8180 (and the TK-7180) you can pull 12 volts off pin 14 on the rear DB-25 connector.
It's switched on and off with the front power switch, along with the radio.
It's limited to 2 amps maximum.
Ground is available on pin 7 and 18.

You would need to use one of the AUX output or AUX I/O pins and a 5 volt relay to control a 12 volt device.

 

[New2radios]

Thanks everyone!

 

[ramal121]

Whoa, not correct. If you want to control an external device via a signalling scheme (selective call) of the radio, you would use the horn alert logic line. This line is only available on a connector inside the radio, not the 25 pin accessory connector. The horn alert line does not have enough poof to drive a relay directly. The best thing to do is get the Kenwood KAP-2 option board which has a 2 amp relay and its contacts terminate on a 6 pin molex connector that's on the end of a pigtail coming out the back of the radio. With that you could Rube Goldberg anything you'd want to control with the radio.

Sans the KAP-2, you could still tap into the horn alert line, but you'll have to invent a buffer circuit to be able to drive a relay.