Device for testing any transistors
This is another article dedicated to the novice radio fan. Testing the transistors is probably the most important thing, since it is a non-working transistor that causes the entire circuit to fail. Most often, novice electronics lovers have problems with checking field-effect transistors, and if you don’t even have a multimeter on hand, then it’s very difficult to test the transistor for operability. The proposed device allows for a few seconds to check any transistor, regardless of the type and conductivity.The device is very simple and consists of three components. The main part is a transformer. For a basis it is possible to take any small-sized transformer from impulse power units. The transformer consists of two windings. The primary winding consists of 24 turns with a tap from the middle, the wire is from 0.2 to 0.8 mm.The secondary winding consists of 15 turns of wire of the same diameter as the primary. Both windings swing in the same direction.The LED is connected to the secondary winding through a limiting resistor of 100 ohms, the power of the resistor is not important, the polarity of the LED is also, because the output of the transformer alternating voltage is generated. There is also a special nozzle into which the transistor is inserted in compliance with the pinout. For direct conduction bipolar transistors (type KT 818, KT 814, KT 816, KT 3107, etc.), the base goes to one of the terminals (left or right terminal) of the transformer through a 100 ohm base resistor, the middle point of the transformer (tap) is connected to the power supply, the emitter of the transistor is connected to the power supply minus, and the collector to the free output of the transformer primary winding.For reverse-conducting bipolar transistors, you only need to change the polarity of the power.The same with field-effect transistors, it is only important not to confuse the pin of the transistor. If after the power supply the LED starts to light up, then the transistor is working, if not, then throw it in the garbage, because the device ensures 100% accuracy of the transistor check. These connections need to be done only once, during assembly of the device, the nozzle allows to significantly reduce the time for testing the transistor, you just need to insert the transistor into it and supply power. The device in theory is the simplest blocking - generator. The power supply is 3.7 - 6 volts, only one lithium battery is perfect - the ion battery from a mobile phone, but you need to remove the board from the battery in advance, because this board cuts off the power consumption of more than 800 mA, and our circuit may consume such current in peaks. The finished device is quite compact, you can put it in a compact plastic case, for example, from tick-type candies, and you will have a pocket-sized device for testing transistors for all occasions.
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