Cheap Bicycle Alarm Schematics Circuit Diagram


The author wanted a very cheap and simple alarm for some of his possessions, such as his electrically assisted bicycle. This alarm is based on a cheap window alarm, which has a time-switch added to it with a 1-minute time-out. The output  pulse of the 555 replaces the reed switch in the window alarm. The 555 is triggered by a sensor mounted near the front  wheel, in combination with a magnet that is mounted on the spokes. This sensor and the magnet were taken from a cheap bicycle computer. 

Circuit diagram :
Cheap Bicycle Alarm-Circuit Diagram
Cheap Bicycle Alarm Circuit Diagram

The front wheel of the bicycle is kept unlocked, so that the reed  switch closes momentarily when the wheel turns. This  triggers the 555, which in turn activates the window alarm. The circuit around the 555 takes very little current and can  be powered by the batteries in the window alarm.  There  is just enough room  left inside the enclosure of the window  alarm to mount the time-switch inside it. 

The result is a very cheap, compact device, with only a single cable going to the reed switch on the front wheel. And the noise this thing produces is just unbelievable! After about one minute the noise stops and the alarm goes back into standby mode. The bicycle alarm should be mounted in an inconspicuous place, such as underneath the saddle, inside a (large) front light, in the battery compartment, etc.
Hopefully the alarm scares any potential thief away, or at least it makes other members of the public aware that something isn't quite right. 

Caution. The installation and use of this circuit may be subject to legal restrictions in your country, state or area.


http://streampowers.blogspot.com/2012/07/cheap-bicycle-alarm-schematics-circuit_06.html 

Comments

Post a Comment

Popular posts from this blog

Simple Active crossover Circuit Diagram with TL074

Image
This is a Simple Active crossover Circuit Diagram with TL074. An audio source, like a mixer, preamp, EQ, or a recorder, is fed to the input of the Electronic Crossover Circuit. This signal is either AC or coupling, depending on the setting of switch 51, the non-inverting input of buffer amplifier Ul-a, a section of a quad BIFET, low amp TL074 noise made by Texas Instruments op. This stage has a gain of 2, and its output is distributed to both a low pass filter made by R4, R5, C2, C3, and Uld op-amp, and a high-pass filter made by R6, R7, C4, C5, and op amp ULC.  These are12 dB / octave Butterworth filters. The response of the Butterworth filter was chosen because it gives the best compromise between the damping and phase. The values of capacitors and resistors varies depending on the selected connection that your device works. The filter outputs are fed to a balancing network made by R8, R9, RIO, R14 and potentiometer RLL balance. When the potentiometer is at its center position, t...
Keep reading

Build a Curve Tracer Circuit Diagram

Image
How to Build a Curve Tracer Circuit Diagram ? This is the simple Curve Tracer Circuit Diagram. This circuit Useful for checking diodes, transistors, triacs, SCRs, resistors, and LEDs, this curve tracer should prove useful in the experimenter`s lab.   Curve Tracer Circuit Diagram It displays the volt-ampere characteristic of a two-ter-minal device on an oscilloscope. This is a simple block diagram of the EZ-Curve. Current-limited AC signals are passed through both the device under test and a precision resistor to yield current and voltage readings.
Keep reading

Making an RIAA phono preamp

Image
Before we start today's blog post, I think I really need to clarify what we’re discussing. I’ve recently got back into vinyl in a big way. Part of the reason for this is the fantastic “Vinyl Decision” in Taipei, run by a couple of very fine gentlemen by the names of Mark and Terry ( https://www.facebook.com/VinylDecision / http://www.vinyldecision.com/ ). If you're in Taipei, and like music, pay them a visit. A recent purchase from there brought back memories of trying again, and again (and again) to play guitar like my guitar heroes as a teenager in the 1980s. In fact, vinyl is making quite a comeback worldwide. A lot of people are realizing that digital versions just lack some of the personality that vinyl can provide. Many of them are buying old record players/turntables and wiring them up to their modern amps. However, they are often disappointed to find that the output audio is very quiet and lacking bass. This is because records are/were recorded using a very specific f...
Keep reading