A common piezoelectric alarm, such as the Murata (Smyrna, GA) PKB5-3A shown, has many valuable attributes. It is compact, lightweight, efficient and reliable. However, the loud, high-pitched sound output can be quite irritating in many applications. The simple and inexpensive circuit provided here transforms this obnoxious little buzzer into a ple
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asantsounding bell ( see the figure ). At the heart of the circuit is the popular 555 timer U1, which is configured as an astable multivibrator. The output low time is a short pulse that initiates the bell strike. The strike time is 0. 693 †” R2 †” C1. For the component values shown, the strike time is 6. 93 ms. The output high time is the sustain time during which the amplitude of the bell tone decays continuously. The high time is 0. 693 †” (R1 + R2) †” (C1). For this circuit, the high time is 236 ms. When the output of U1 is low, the series transistor switch Q1 turns on through bias resistor R3 to energize the piezoelectric alarm AL1 and charge capacitor C3. When the output of U1 is high, Q1 is off and the output of AL1 decays until C3 is discharged. When C3 is discharged again, the cycle is repeated. The values of timing components R1, R2, and C1, along with decay capacitor C3, aren`t critical; various sound effects can be produced by experimenting with them.
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.....
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