I designed this project for another boy who had a much bigger box of electronic scrap than me so he supplied most of the bits for it. I made it in few evenings besides doing my homework. We wanted it to play a bit of a tune so we looked through the Maplin Catalogue and on page 1200 there is a silicon chip type M66T which will do just this. The chi
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p is available in several versions, playing different tunes and we settled on the M66T-02B playing twinkle twinkle little star. The cost of the chip was £0. 49 and needs no added output stage to drive a small loudspeaker. There was a typical sample circuit in the catalogue so I built it to this circuit and I found that the volume was high enough but the silicon chip played continuously as long as the supply was maintained. The problem was how was I going to get that to be a doorbell A lazy way of doing it would be to put the bell push in series with the battery supply but since most people press a bell push in the same way that they press the keys on a computer keyboard, this would only give one or two notes of the melody so I decided that a timer circuit was needed which would trigger when the push switch was operated and would hold the circuit on for the few seconds of the tune. I looked through the junk box again where I got the loudspeaker from and found a 1000 µf electrolytic capacitor which would hold its charge for a few seconds and keep the relay RLA1 operated for the time of the tune. The relay needed 9 volts at low current but the loudspeaker circuit needed only 3 volts at a higher current so I decided to have separate batteries to operate the different parts of the circuit. Also if the transistor switches the current to the IC directly it gives an odd effect at the end of the tune as if the musician playing it...
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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