An interesting hobby circuit of a crank door bell! The circuit is built around a timer 555 and a musical piezo-buzzer. The circuit works off 9 volt battery supply. One 9volt PP3/6F22 compact battery is enough for powering the whole gadget. Timer IC (NE555) is wired in monostable mode to produce a time out o some seconds. The output of t
Click here to download the full size of the above Circuit.
he timer is fed to the input of the piezo sounder through a diode D1. Capacitor C2 works as a buffer. RC components R2, C1 sets the monotimeout of the timer IC NE555. An ordinary low voltage small dc motor is here used as the crank switch. In prototype, one small disc motor from a discarded cd drive (optical deck) was used. Even a slight rotation of the motor shaft will produce sufficient counter emf to enegize the LED(S) inside the ac opto-coupler PS2505. As a consequence, phototransistor inside PS2505 conducts and there by it pull down the trigger input (pin2) of IC NE555. The result is a loud but pleasing musical tone output from the piezo sounder for a finite duration, here around seconds. One can easily replace the musical buzzer with an EM relay for switching external loads. A 9 volt/600 Ohm relay is preferred for this modification. The circuit can also be used as a two wheeler security aid which senses the wheel rotation of a parked vehicle and sounds an alarm to alert the owner. With a little skill, one can easily attach the crank mechanism (like the dynamo-wheel assembly) to any vehicle. However, for burglar alarm application, a latching output circuit is highly recommended.
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: