Domelight Supervision Not Triggering Relay

The TIP42 in Pic 1 is a PNP transistor. Pic 2 shows a circuit for an NPN transistor so won't work with the TIP42.

eguru wrote: The TIP42 in Pic 1 is a PNP transistor. Pic 2 shows a circuit for an NPN transistor so won't work with the TIP42.

How is 2 positives and a single negative a npn circuit? Pic 2 is based off of the data sheet images I dug up. I'm new to this level of circuitry so I don't doubt I did it wrong I'd just like some more explanation as to what it is I goofed up. Edit: Do I need to reverse the collector and emitter?

Have you tried contacting the seller to swap out the unit?Steve G

iskidoo wrote: Have you tried contacting the seller to swap out the unit?

I already cut all the unused wires so it's not really an option. Not to mention, based on what my dmm says, the alarm is functioning just fine. Yet something is amiss.

That diagram works. It has been used many times. Take a picture of your setup and post it.

rooney77 wrote: eguru wrote: The TIP42 in Pic 1 is a PNP transistor. Pic 2 shows a circuit for an NPN transistor so won't work with the TIP42. How is 2 positives and a single negative a npn circuit? Pic 2 is based off of the data sheet images I dug up. I'm new to this level of circuitry so I don't doubt I did it wrong I'd just like some more explanation as to what it is I goofed up. Edit: Do I need to reverse the collector and emitter?

NPN and PNP are used to describe the fabrication (the doping of the individual silicon structures) of the transistor and do not refer to the polarity of the external connections. In Pic2, the Base needs to be positive wrt the Emitter so that current can flow from the Collector to the Emitter. Since the alarm feed to the Base is ground when active, the NPN transistor won't turn on. Pic 1 with the TIP42 (PNP transistor) should work - although I would like it better if there was a 120 ohm resistor in series with the Base lead.

So I connected the transistor in the same manner as pic 1. It's ghetto I know but I'm trying to be sure it all works before I final wire it. Also, you're looking at the backside of the transistor. After connecting the transistor I put the black lead of the dmm on the signal into the relay (85) and the red on the constant 12v (86). When the alarm is unlocked I got voltage (2v for some reason, straight from battery) and it was there for 30s as expected. Relay did not trigger though. With the 12v constant and signal connected only to the dmm I'm seeing the full 12v.looks like there's a significant voltage drop in the resistor. Yes I know it all looks like crap right now but the 3rd pic shows what it will look like, that's my door lock replays.

Checked my other resistors and I see that same voltage drop so I assume it's normal.

The trunk release lead does trigger the relay. Is there a way to measure the strength of the signal from the alarm?

eguru wrote: rooney77 wrote: eguru wrote: The TIP42 in Pic 1 is a PNP transistor. Pic 2 shows a circuit for an NPN transistor so won't work with the TIP42. How is 2 positives and a single negative a npn circuit? Pic 2 is based off of the data sheet images I dug up. I'm new to this level of circuitry so I don't doubt I did it wrong I'd just like some more explanation as to what it is I goofed up. Edit: Do I need to reverse the collector and emitter? NPN and PNP are used to describe the fabrication (the doping of the individual silicon structures) of the transistor and do not refer to the polarity of the external connections. In Pic2, the Base needs to be positive wrt the Emitter so that current can flow from the Collector to the Emitter. Since the alarm feed to the Base is ground when active, the NPN transistor won't turn on. Pic 1 with the TIP42 (PNP transistor) should work - although I would like it better if there was a 120 ohm resistor in series with the Base lead.

Thanks for the info. I appreciate you explaining it.