Thread: Windows Service that raises DTR on powerup

can i use my 12v ignition wire as the base and then seral port at the collector..
if u say the emitter is a diode drop lower than the baese then it should come out as 11.5v?

Originally Posted by djmickyg

what does it mean by flipping the dtr line?

I meant inverting.

Originally Posted by djmickyg

can i use my 12v ignition wire as the base and then seral port at the collector..
if u say the emitter is a diode drop lower than the baese then it should come out as 11.5v?

Nope. Go read how transistors work, you want your control signal at the base, that is what it is for.

Wow, this worked great for me - I'm using a usb-serial converter, with the DTR wire triggering my amp. Finally I have a way to power the amp without EVER hearing thump - standby, hibernate, full-shutdown. Thanks a lot DaTeach!

Originally Posted by Hark

Wow, this worked great for me - I'm using a usb-serial converter, with the DTR wire triggering my amp. Finally I have a way to power the amp without EVER hearing thump - standby, hibernate, full-shutdown. Thanks a lot DaTeach!

did u connect it straight to the amp from pin 4??

I can say I hooked up the serial cable right up to the amp remote line and it works. I have changed it though and I have it now so it goes through a relay. That if the the Accessory is on then it jumps the relay to enable DTR from the serial port to go to the amps but if the accessory is off it cuts that.

DTR will ditch the startup speaker pop by itself but I was also having a turn off speaker pop so that fixed that and its perfect now.

dam why wouldnt it work for me directly in
i was only geting 6V out the dtr line.. grr

doesnt mater i dont have the car anymore so nowhere to put the pc

Some amps can't handle the lower voltage maybe yours had a problem or maybe you shorted it slightly. Your problem would of been easily fixed with a relay that was triggered by the DTR and kicked on 12v from the accessory to the amp.

I'm testing this on my laptop to make sure it works before I tear into my car stereo wiring. Can somebody confirm that how I'm testing it and what I'm seeing in my testing is correct?

I installed the AmpCtrl.exe service and configured it to work on port 3...my USB port. I plugged this USB-Serial converter into my USB port. When I turn on the computer, I connect my multimeter to pins 4 and 5 of the male-terminated serial cable like this:



The multimeter shows a constant 9.06V. Just before the Windows boot screen appears, it swings between -1V and -4V for a second or two...then back to a constant 9.06V. Is this about what I should expect?