Two Relay-Based Motorcycle Alarm Circuits

Posted on Feb 6, 2014

These are two - easy to build - relay-based alarms. You can use them to protect your motorcycle - but they have many more applications. If you use relays with 6-volt coils - they`ll protect your `Classic Bike`. Both alarms are very small. The completed boards occupy about half a cubic-inch - 8 cc. The standby current is zero - so they won`t drain

Two Relay-Based Motorcycle Alarm Circuits
Click here to download the full size of the above Circuit.

your battery. Circuit Number Five uses a SPCO/SPDT relay - but you really only need to use a SPST relay. If you are going to use the veroboard layout provided - you`ll need to use the style of relay specified. But you can build the alarm using whatever style of relay you have available. Any number of normally-open switches may be used. Fit the mercury switches so that they close when the steering is moved or when the bike is lifted off its side-stand or pushed forward off its centre-stand. Use micro-switches to protect removable panels and the lids of panniers etc. When one of the trigger-switches is closed - the relay will energize and the siren will sound. You can choose what happens next. If you build the circuit as shown, the siren will continue to sound until you turn it off - or until the battery is exhausted. But, if you leave out D3 - the siren will stop sounding immediately the trigger-switch is re-opened. While you`re within earshot of your machine - the former configuration is best. You can always turn off the alarm yourself. But if you are going to be away from your bike for any length of time - and you don`t want to cause a nuisance - then the latter configuration is probably more suitable. If you include a SPST switch in series with D3 - you can select the behaviour that best suits the circumstances at any given time. Relay coils and some sounders produce high reverse-voltage spikes that will destroy sensitive...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    TV Modul½±tor
    Electric Heater Thermostat
    TPS3803G15 Single Voltage Detector
    Simple dimming lights circuit diagram
    1Hz clock signal generator circuit
    With a CD4011 CD4518 making colorful cycle decorative lights