Anyone who decides to go into amateur radio usually starts with a power source for their future circuits. This article shows the simplest options for stabilized feed sides.
The circuits are not complicated and it will not be difficult to assemble them even to a radio amateur without experience. All the parts are of general consumption, cheap and easy to find. The parameters of these power supplies fully satisfy the requirements of most practical electronic "homemade products".
Scheme N1
The first circuit is based on transistors. It has been widely known since ancient times and is presented here in the form in which it was originally published in various literature on radio electronics. Since at that time germanium transistors were widely used, they made it, as a rule, using transistors of the structure p-n-p.
In this circuit, for example, as a transistor VT1 used MP39 - MP42, and as VT2 - P213-P217. Therefore, for such a power supply unit (PSU), the output is the negative wire, and the "plus" of the circuit will be "common". But you can change the polarity of the PSU output by simply replacing the transistors with similar, but structures n-p-n. At the same time, it is also necessary to change the polarity of all diodes and electrolytic capacitors.
The output voltage of this PSU is determined by the stabilization voltage of the applied Zener diode D1. If, for example, put D814 with the letters G or D, then at the output we get the voltage 12... 14 volts. The maximum output current of this PSU depends on the type of transistors used. ("Powerful" VT2) and from rectifier diodes. Transistor VT2 must be installed on the heatsink.
The alternating voltage at the input of the PSU should be equal to the value of the output constant, or slightly more. Variable resistor R2 may be resistance from 10 to 50 kΩ, group "A" is better (in this case, the regulation of the output voltage will be more uniform). All other resistors must be at least 0.25 watts. Transistors can be installed in any suitable power. Their gain must be at least 15.
The adjustment consists only in the selection of a resistor R1. With its help, the current through the zener diode is set at the level 15 mA. To reduce the level of ripple at the output of the circuit, you can install an additional "smoothing" capacitor, with a capacity of 100 uF. It should be noted that this power supply circuit does not have protection against output short circuit (short circuit) and overload.
Scheme N2.
Second circuit assembled on a specialized microcircuit - voltage stabilizer. This could be ours KREN12 or imported LM317. This circuit is simpler than the first, but the microcircuit provides better performance, as well as protection against short circuit, overheating and overload. Shown here is a “step” setting for the output voltage. By selecting resistances R2-R6 you can set any voltage value at the output of the power supply unit.
This microcircuit is capable of issuing from 1.2 to 37 volts, therefore, the range of output voltages can be extended, in contrast to the values indicated in the diagram. The alternating voltage at the input is also selected depending on the required maximum output voltage. The microcircuit must be installed on the heatsink.
The ripple level of such a circuit will be at the level 10 mV. At the output of the power supply unit, you can install an additional capacitor with a capacity of 100 uF or more to reduce the level of ripple.
The operating voltages of all capacitors must be higher than the input voltage after the rectifier. All resistors can be of type MLT-0.125.
This power supply unit can be made with smooth output voltage regulation. In this case, the circuit is extremely simplified, as can be seen from the third figure.
There is no need to make any settings at all. For this option, all the recommendations that were given for the previous scheme with step regulation are correct.
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