Parametric stabilizer on a transistor and a zener diode

As you know, no electronic device works without a suitable power source. In the simplest case, a normal transformer and a diode bridge (rectifier) ​​with a smoothing capacitor can act as a power source. However, it is not always at hand there is a transformer at the desired voltage. And even more so, such a power source can not be called stabilized, because the voltage at its output will depend on the voltage in the network. The solution to these two problems is to use ready-made stabilizers, for example, 78L05, 78L12. They are easy to use, but again not always at hand. Another option is to use a parametric stabilizer on a zener diode and a transistor. Its diagram is shown below.

Stabilizer diagram

The parametric stabilizer on the transistor and the zener diode
VD1-VD4 on this circuit - the usual diode bridge,converting AC voltage from transformer to DC. Capacitor C1 smoothes the ripple voltage, turning the voltage from pulsating into a constant. In parallel with this capacitor, it is worthwhile to put a film or ceramic capacitor of a small capacity for filtering high-frequency pulsations, since at high frequency, the electrolytic capacitor does not do its job well. Electrolytic capacitors C2 and C3 in this scheme are for the same purpose - smoothing any ripple. The chain R1 - VD5 is used to form a stabilized voltage, the resistor R1 in it sets the stabilization current of the Zener diode. Resistor R2 load. The transistor in this circuit extinguishes all the difference between the input and output voltage, so a decent amount of heat is dissipated on it. This scheme is not designed to connect a powerful load, but, nevertheless, the transistor should be screwed to the radiator using heat-conducting paste. The voltage at the output of the circuit depends on the choice of the Zener diode and the value of the resistors. Below is a table that lists the values ​​of the elements to get 5, 6, 9, 12, 15 volts at the output.
Parametric stabilizer on the transistor and zener diode
Instead of the transistor KT829A, you can use imported analogs, for example, TIP41 or BDX53. A diode bridge is acceptable to put anyone that is suitable for current and voltage. In addition, it is possible to assemble it from individual diodes. Thus, by using a minimum of parts, an efficient voltage regulator is obtained, from which other electronic devices that consume a small current can be powered.


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