Although you may well be the proud owner of the very latest NiCd battery charger, you may still come across the odd `incompatible` battery, for example, one having a rare voltage or requiring a much higher charging current than can be supplied by your off-the-shelf charger. In these cases, many of you will resort to an adjustable mains adaptor (sa
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y, a 500-mA type) because that is probably the cheapest way of providing the direct voltage required to charge the battery. Not fast and not very efficient, this `rustic` charging system works, although subject to the following restrictions: You should have some idea of the charging current. In case you use an adaptor which is adjustable but of the unregulated, low output current type, you can adjust the current by adjusting the output voltage. You have to know if the current actually flows through the battery. A current-detecting indicator is therefore much to be preferred over a voltage indicator. To prevent you from forgetting all about the charging cycle, the indicator should be visible from wherever you pass by frequently. Using the circuit shown here, the LED lights when the baseemitter potential of the transistor exceeds about 0. 2 V. Using a resistor of 1 as suggested this happens at a current of about 200 mA, or about 40 mA if R1 is changed to 4. 7. The voltage drop caused by this indicator can never exceed the base-emitter voltage (UBE) of the transistor, or about 0. 7V. Even if the current through R1 continues to increase beyond the level at which UBE = 0. 7 V, the base of the transistor will `absorb` the excess current. The TO-220 style BU406 transistor suggested here is capable of accepting base currents up to 4A. Using this charging indicator you have overcome the restrictions 2 and 3 mentioned above.
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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