This is a rather old project I`ve done around 2005 but was not published on my website until now. The idea of building a torch using a glue stick came to my mind when I realized that an AA battery fits perfectly into the glue stick`s plastic case. To make a complete battery holder there is also the need to make contacts for the positive and negati
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ve connections on the battery. The negative contact is made by cutting the plastic worm gear inside the stick, making a hole in it and passing a wire through the hole. The positive contact is made with a metal wire folded on top of the battery and kept in place using a spring. This makes it easy to replace the battery. The wire of the positive contact ends close to the black "knob" on the bottom, so that when turning the knob it makes contact with another wire, resulting in a switch to turn the torch on and off. I wanted to use two white LEDs as light source for this torch, but this turned out to be a problem because a white LED requires ~3. 6V to operate, while an AA battery is only 1. 5V. So I had to come up with some sort of switching step-up circuit to provide 3. 6V (or 7. 2V if wiring the LEDs in series) from an input voltage that varies from 1. 5V down to less than 1V (because battery voltage decreases as the battery discharges). And the circuit needed to be small enough to fit into the tiny space available into the black knob of the glue stick. If the base of the transistor is kept at 0V Vout is just Vin-0. 7 (the voltage drop of D1) because the inductor acts as a wire. But if a square wave is applied to the base of the transistor, it acts as a switch opening and closing. When the transistor is closed the inductor is connected to Vin and ground, and the current in it increases linearly with time, while when 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....
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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....
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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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