9A3KB - DC power source, not stabilized, with output voltage adjustment


This power source is simple. As you can see on the schematic, transformer Tr1 primary is connected through heavy resistor 1k/25W. After 10 seconds resistor will be bypassed with relay timer contacts (5-6) . This time is enought to fill 150miliFarad filter capacitors through diode bridge. I used 60VDC timer with 6k8/7W because I have it. The second relay timer contacts (1-8) will power transformer Tr2. Its 24V secundary will activate 24V relay and its contacts will put the output power. If I need to regulate output potential, I can connect optional autotransformer - variac Tr3. With push buton I will activate another relay to disconect Tr1 from 230VAC main supply and connect it through Tr3. When the relay is activated its contacts (1-3) will bypased push button.

I planed to build another one power source. I need to increase output potential. To do it I need transformer with highest potential. The second diferent will be variac inside the box.

Some pictures and schematic: