A question hehe

[Mad Mick]

The transponder in a key bow is an active device, but only transmits a signal when placed near the induction loop of the vehicle ignition.

Not being nit-picky, but these are passive devices. The proximity to the induction loop/ring antenna/whatever, induces the working voltage required by the transponder chip via a coil winding contained within the device itself.

[fixer]

The transponder in a key bow is an active device, but only transmits a signal when placed near the induction loop of the vehicle ignition.

Not being nit-picky, but these are passive devices. The proximity to the induction loop/ring antenna/whatever, induces the working voltage required by the transponder chip via a coil winding contained within the device itself.

Hmm, well, it depends on your viewpoint.

The resistor chips in the older GM keys are passive devices. They don't do anything with or without power.

Transponders are active devices since they transmit a signal. However, they only get power when within range of an induction loop. But they are still an active device.

[kodierer]

It is possible to duplicate keys which have transponders in them, so that the engine will start. As some keys require the transponder, so that people can't go to ace hardware or something with the key they "borrowed" and duplicate it, and start the car.
However a locksmith with the proper equipment can duplicate not only the cuts on the key, but the transponder chip in it as well, but walmart for instance can't.
The equipment for the duplication is possible, but a device which can work on all cars doesn't exist. There is more than likely a way to rewire a vehicle so not to require the transponder at all, but thats a completely different topic.
Perhaps we should cease before we get into trouble with this topic.