Trying to fix manufactures problem.

Trying to fix a automotive Bluetooth mute circuit that will not trigger a automotive relay.
The unit output is very high impedance - 1meg so I try is a simple relay driver with a TIP42 PNP (all I had laying around at the shop). This seem to work, but some times not release the relay. So try put a 1K on the base but this will not trigger relay.
I contacted the manufactures tech and they recommend a reed relay to trigger the automotive relay. As I read reed relay I cringed for fear of it locking up or worse in the bumpy car ride, triggering randomly.
So if any one help a guy out, I would much appreciate it.
I can build anything if given instructions.
Almost forgot the coil is about 90ohms on the automotive relay
**broken link removed**

Reed relays are not any more sensitve to bumps than automotive relays. the little wires used in them will only move with a magnet, you can not bump them on.

Hi,

the TIP142 is an NPN-darlington transistor and you used the wrong symbol for it.

The transistor to be used should be a PNP-darlington transistor, such as the TIP145 (TIP146 and TIP147)

I doubt that the base current will be high enough to saturate a PNP darlington. It can stand a collector current of 10A!

Why not use a P-channel MosFet like the BS250 to drive your relay? The gate voltage has to be low in order to make it switch and uses almost no current.

Boncuk

suspect the added resistor of 1K might be an open or developed high resistance
.