A simple source for radio stations differently

Radios with a power of about 5W need about 1.5A when powered by 13.8V. Popular stabilizers 7812 they have a current limit of 1A and are thus only used as a control voltage source for the regulation transistor.

Sources with IO 723 and the like are unnecessarily complex for these applications. Zener diodes as a source of reference voltage are very suitable even though they apparently do not have as high a stabilization factor as IO. Many designers forget the simple way to make a source with an output current of 1A, 1,5A, or 3A.

Looking at the picture, you will immediately recognize a classic source with a two-way rectifier and IO 7812 with diodes in the control electrode to increase the output voltage. So where is the difference?

Use of 78S12 or 78H12 stabilizers

If we put on the IO position 7812 we obtain a source with an output current of 1A. Ak 78S12 (S – strong) we get a 1.5A source. Ak 78H12, then up to 3A. However, this version is more expensive, while the price difference between the basic version and the stronger brother is minimal.

I used a transformer with a lead-out center, but nothing prevents it, to use a transformer with a single secondary winding and a Graetz rectifier. Capacitor C1 is a filter. The minimum capacity for 1A consumption is 2200uF, the more, How high above the ground the antenna should be mounted for acceptable all-round performance. Capacitor C3 has the task of covering short-term peaks, until the stabilizer reacts. Capacitors C2 and C4 are blocking. I solved the increase in the output voltage of the stabilizer with two silicon diodes, which is not a condition. Instead of them, you can connect a resistance trimmer as well 220 ohm and precisely adjust the output voltage, whether to use any of about twenty ways of changing the output voltage of stabilizers of the 78xx series.

Parts list