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Um...Me123

Car Alarm

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Just Installed a car alarm for my friend and saw that the basic way in which is works is very simple.  I want to build a simple system for my own car, which happens to be wayyyyyyy more prone to a break in than his anyway, using some shock sensors and possibly door detection (using dome light wiring and a hood pin)  Has engine imobilizer (sp?) so I don't know if it's worth the trouble.  I just don't want kids at school to be messin around with my car.

Below is where I'm at in my basic concept of transistors.  Please let me know if in the instance either button is pushed the light (marked alarm) will illuminate.

The program gave me an error with the PNP and I just attempted to grasp their concept today so I don't know.

Thanks all!

post-11508-14279142927804_thumb.jpg

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Your circuit has the collector-base diode of the PNP transistor forward biased and shorting the battery.
Transistors always have the collector-base connected with reverse bias voltage.

Your NPN transistor is connected correctly as an emitter-follower, however the transistor might fail because a light bulb draws about 10 times its normal current when cold.

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just curious why you chose transistors for a car alarm instead of digital gates, like OR gates and AND gates to make some logical choices of when and why an alarm is set.

MP

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