i need a power supply +/-5 volts. After , i was thinking what should o do if i need 12 or 9 or 15 volts.
So i make a symmetrical adjustable power supply +/- 0-20 volt
Positive/Negative Adjustable Voltage Regulator Module.
Based on LM317 / LM337 Regulator IC Design, AC Input, DC Output.
Complete Series of Protections (IC Function), Current Limiting, Thermal Shutdown and SOA Control. With Protection Diodes Circuit.
You can adjust separate the positive or the negative voltage.Voltages can be added or abstract and the output voltage in my situation that is used +/-15 volts transfomrer , can be reached to 40 volts
The power supply is based on the LM317 and LM337 variable 3-terminal regulators ICs, and while it is no powerhouse, it is quite satisfactory for testing most power amps, as long as there is no speaker connected.
The transformer does not need to be especially large – typically a 60VA unit should be sufficient, although a larger one will do no harm. Likewise, the 4,700uF caps will be quite large enough for the intended purpose,so you could use 2200. The bridge rectifier should be rated at about 5A for continuous operation.