From: "gert baars"
Subject: Re: battery-operated anti-burglar circuit
X-Newsreader: Microsoft Outlook Express 5.00.2919.6600
Date: Sat, 02 Nov 2002 07:56:02 GMT
NNTP-Posting-Date: Sat, 02 Nov 2002 08:56:02 MET
Organization: Chello Broadband
This is very easy to do with a transistor or FET. Tie the detectionloop (to
be cut) between the base and emitter
of a NPN transistor. Tie the emitter to the - of the battery. In series with
the collector of the transistor put the
coil of the relays and tie the loose end of the coil with the plus of the
battery. Put a resistor of app. 10 Kohm
between the base and the collector. Put a diode in parallel with the coil of
the relais with the anode tied to the collector side.
Now you are finished.
"itshardtogetone" schreef in bericht
> I wish to design a simple battery-operated anti-burglar circuit.
> if someone cuts the wire, the alarm will sound. This is quite simple to
> build and I have the following :-
> When the circuit is closed, it energises the relay which then cut out the
> supply to the alarm, and if the circuit is "opened" (wire cut by burglar
> eyc.) , the relay de-energise and the alarm sounds. However, in this kind
> design, it consume my battery.
> Could someone help me to think of a better design whereby if the wire is
> cutted by burglars, the alarm will sound. I need to operate this device
> about 9hrs per day, therefore consumption of battery should be as little