This circuit can switch two or more devices on and off in response to a series of rapid handclaps. The claps are picked up by an electret microphone and amplified by a 741 op amp (IC1). IC1 is configured as an inverting amplifier, with its gain and hence the sensitivity of the circuit adjustable via trimpot VR1. Its output is then fed into a pulse
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-shaping stage based on a 555 timer (IC2). The 555 is configured as a monostable multivibrator, with its trigger input (pin 2) normally biased to about 0. 4VCC by the 150kW and 100kW resistors. When a loud enough sound is detected, pin 2 will be pulled below 1/3VCC, triggering the monostable. The output (pin 3) will immediately swing high, causing transistor Q1 to conduct. The result is a 250ms low-going pulse at the collector of Q1. The output from the pulse-shaper stage is fed into a missing-pulse detector based on a second 555 timer (IC3), which is also configured as a monostable multivibrator. However, this monostable circuit differs from the first because it includes a "retrigger" function. Retriggering is made possible by transistor Q2, which acts to rapidly discharge the 10mF timing capacitor should a pulse arrive when the timer is already running. This means that once triggered, IC3`s output will remain high as long as additional trigger pulses are received within its set timing period. Pulses from Q1`s collector are also applied to the clock (CP0) input of a 4017 decade counter (IC4). In the initial state, output 0 (pin 3) of the counter is high, illuminating LED1. The first pulse advances the count and lights LED2, indicating that the circuit is active and ready to receive a handclap "command". Each time another pulse (clap) is received before IC3`s timing period expires, the process repeats, incrementing the...
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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