need help with cdm1250 accessory connector

pmppk · Post by **pmppk** » Tue Apr 20, 2004 12:22 am

Hi all. I have a strobe system in my car, along with a CDM1250. In the interest of space and convenience I'm trying to set everything up so that I can turn the strobes on and off using one of the programmable buttons on the radio. I have the radio programmed to toggle pin 12 as Aux 1, and I have verified that it correctly switches about 4.8V (using pin 7 or the chassis as ground) on and off at this pin when I press the button assigned to switch it. The strobe pack expects 12V on the switch, so I built a little relay assembly using a 5V reed relay from radio shack. My problem is, I cannot get the radio to trip the relay. I have tried two different types of relays with the same result, and I know that my soldering and such is good, as I am able to successfully trip the relay (and turn on the strobes) using a 2.5V battery. What could be my problem? Do I need a different type of relay, or am I doing something else wrong? Any advice would be greatly appreciated.
THanks,
Pete

jim · Post by **jim** » Tue Apr 20, 2004 5:39 am

Use a 2N2222 transistor to switch the relay. Program the button to provide 0VDC when depressed. Provide a slight positive bias on the base of the transistor with a 100-150K transistor to +12V to ensure it shuts down when it should. Don't forget to put a 1N1007 diode across the relay in reverse polarity.

jim · Post by **jim** » Mon May 03, 2004 6:03 pm

Ooops! I just re-read this and saw that I wrote "100-150K transistor." Of course, that should read "100-150K RESISTOR!"

What a schmuck.

thebigphish · Post by **thebigphish** » Mon May 03, 2004 10:07 pm

yeah, you're fired.

pmppk · Post by **pmppk** » Mon May 03, 2004 10:20 pm

Heheh I realized what you meant from the context of the sentence, thanks. I haven't had the chance to try it out yet, hopefully I will in the next day or two. I'll let you know how I make out.

pmppk · Post by **pmppk** » Wed May 05, 2004 9:27 am

Success! I went with something slightly different from your suggestion to avoid having to repogram the radio. I put the emitter of the transistior to pin 7 on the radio (ground), the collecter to 12V, and put the programmed pin to the base. And of course, a diode in reverse across the relay.Works like a charm! Thanks again for your help, I had really hit a dead end until I posted here.
Pete

werdnuts · Post by **werdnuts** » Thu May 06, 2004 8:40 am

the two pins with aux output ability vary in output power. one puts out something like .1 amps. the other puts out a small fraction. it is made to work with data control type stuff... (other sophisticated hardware, not dumb relays.) the trick would be to use some sort of sensative relay or some sort of transformer... either way, you want to be careful how much juice you pull through the radio. it wouldn't be cool to fry a radio just because you didnt want to buy a 50cent switch.

i found a workaround for the the aux1 output for a relay. i used a radio to control a commercial garage door on a temporary basis. we used mdc to open and close the door -- one code for open and one for close. i wired the open stage of the standard relay to trigger the close button, when you applied voltage it would close the relay and trigger the open button. by setting the aux pin to toggle, it would remain open until you sent the close cold. incase of radio failure, the door would automatically close.

simple, dirty, and very last minute, but it worked like a charm.

hope this helps!

-werd