The halogen or krypton bulbs in modern torches (USA and Canada: flashlights) have a limited life and are not particularly cheap. A simple modification in the torch lengthens the life appreciably. It is a fact of nature that any incandescent bulb has anite life. However, the bulbs in modern torches (US and Canada:‚ashlight) have a less-than-
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average life. The reason for this is that the halogen or krypton bulbs used are operated at over-voltage to give as bright a light as feasible. The life of these bulbs may be extended simply by connecting a resistor in series with the bulb. For instance, when the battery voltage is 6V and the bulb is a 500mA type, a series resistor of 1 will reduce the voltage across the bulb by about 0. 5V. This will certainly lengthen the life of the bulb, but it will also cause a reduction in the available brightness. Also, energy is wasted in the resistor (evinced by heat production). Clearly, this is not a very good solution to the problem. A better one is shunting the bulb with a transistor in series with a resistor. Another well-known fact is that incandescent bulbs normally burn out when they are being switched on. This is because the resistance of the cold filament is significantly lower than that during normal operation. This results in a switch-on current that is much higher than the normal operating current. Clearly, much is to be gained by damping the switch-on current. The switch-on current may be limited by a simple circuit that is small enough to allow it to be built into most types of torch. As the diagram shows, such a circuit consists of nothing more than a metal-on-silicon-field-effect-transistor, or MOSFET, and a resistor. The transistor may be almost any current n-channel type that can handle the requisite power. 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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