This symmetrical unregulated power supply is used to feed the audio amplifier based on LM1875 amplifier module National Semiconductor. With symmetrical 30V DC source the amplifier capable of delivering up to 30W of power using 8 ohm load.
This lm317 variable power supply can supply a voltages from 1.2V to 30V with a current 3 amperes, just as the title of this series based on LM317T voltage regulator, the LM317T regulator provide around 1.5 amperes on the heatsink, so by installing a parallel two or three of them will get a voltage source capable of providing 3 amperes. Obviously this also depends on the transformer used.
This power supply circuit shows a steady source of continuous power supply combined with an output of +5 VDC and +12 VDC to ground, it is estimated for designing a current of about 900mA Max, enough to power any digital circuit with a relay output,that must be taken into account is the cascade design makes total consumption is the sum of the currents provided by the two outputs. Please note that the regulator should be equipped with a heat sink.
Here is a power supply circuit for sega game gear for the additional collection of your circuit. For a more complete explanation can be found on the website http://hardware.speccy.org.
Note: The value of the supplies provided by this sega power supply circuit, only take from the game gear and can not measure the value of the original circuit.