The electronic bicycle lock is a worthwhile alternative for bicycle owners who want to make their bicycles ‘intelligent’ at reasonable cost. The circuit can be used for any make of bicycles.

In the Electronic Bicycle Lock circuit, input jacks (J1 and J2) which are two standard RCA sockets are used. A security loop (made in-house) is used to link these two input points, it is about 50cm long and is a basically a standard 14/36 flexible wire with one RCA plug per end. The circuit of the Electronic Bicycle Lock is powered by a compact 9V battery (6F22). Key lock switch S1 and smoothing capacitor C2 are used for connecting the power supply. When the loop is connected, UM3561 (or IC1) remains deactivated and therefore the speaker does not sound. When the loop is broken, zener diode ZD1 (3.1V) receives operating power supply through resistor R2 and enables the tone generator UM3561 (IC1). IC1 remains enabled until power to the circuit is turned off using switch S1 or the loop is re-plugged through J1 and J2.

Click here to access the pdf.