CAR ALARM
INSTRUCTION SHEET
Schematic Diagram
PCB Layout
WIRING INFORMATION
W1
12V Positive. Connect to a terminal that remains live with the ignition and accessories switch off - eg. the electric clock, a point on the main fuse block, the starter solenoid pole that comes direct from the battery. Do not connect the alarm direct to the battery poles as drop in voltage needed to activate the system will not register.
W2
0 V. Any earthing point on the metal frame or chassis willdo - eg. a bolt or screw that attaches to the body. W3 External Trigger. Touching this wire to Ov (earth) will activate the alarm. This could be wired to the door switch (for the interior light). When the door is opened, interior light switched on or off, the trigger will go low and activate the alarm. A mercury switch could be located to the boot lid or the engine compartment hood so, if either is opened the trigger will operate.
W4/W5
A and K wires to the blinking LED, mounted where it can be easily seen.
W7/W8
Relay output.
1. If the alarm is to operate the car's horn then run a wire from the -ve
horn terminal to W7 and another from W8 to earth. This assumes that the horn is
normally activated by pressing the horn switch which closes the horn circuit to
earth. Most operate this way.
2. If a screecher is used a l2v + wire is
connected to w7. The Piezo screecher is connected in series with the red (A)
wire to W8 and the black wire to an earth point. The 12V + wire can be an
extension of the 12V+ wire to Wl.
SWITCH
The on/off switch should be accessible from outside the vehicle but concealed from view. A key switch is an inexpensive way of adding to security. The 12V + supply to the alarm unit must pass through the switch. The alarm is switched on after the vehicle is locked. If the alarm senses even a minute Voltage drop caused by a light going on, radio switched on, starter operated etc. it will squeal. The alarm will continue for a cycle of about 45 seconds and reset itself. The sound can be stopped at any time by switching the power off to the unit. The unit is extremely sensitive to voltage drop. If the location of the on/off switch is carefully planned this unit will give a very high order of security. No amount of care or stealth will fool the system. Assoon as the electrical system is used in any way, the alarm will sound.