A simple Zenner diode tester circuit, when coupled with a PWM generator it can be used to measure the breakdown voltage of Zener diodes. Or more generically, it can be used to measure the breakdown voltages (e. g. BVceo, BVcbo) of BTJ transistors. As you can see, the circuit is consisted of a simple flyback converter to generate the high voltage needed for the breakdown condition and a constant
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current source to limit the current flowing through the device under test. The transformer is modified from the inductor in a CFL bulb. Since a CFL typically switches at around 25, 000 Hz, we can tune our voltage converter to operate at roughly the same frequency to minimize the converter loss. In order to use the flyback configuration, a separate winding must be made as the primary. This can be easily done by using magnet wire to wind a few dozen turns outside the inductor coil. The exact number of turns needed is dependent on the desired output voltage. In my example, the ratio between the primary and secondary windings is roughly 1:25, and the DC output is around 150V. We could have just used a resistor to limit the output current. The main issue of this approach is that the current flowing through the device to be tested depends heavily on the breakdown voltage of the device. In order to make this current constant, two high-voltage BJTs are used to form a constant current source. The output current is determined by the value of Vbe (typically around 0. 7V) and the resistor between the base and the emitter. For the components value given, the current is approximately 1mA. Since the hFE of BULT118 is rather small, the performance of the constant current source is relatively poor, but it is still magnitudes better than the simple resistor current limiting approach. To improve the current source performance, you can use...
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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