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A simple solar panel regulator by TLC271
Solar panel regulators come in many flavors. The plainest flavor is the simple on-off type shunt regulator. It has the advantage of simplicity, extremely small power dissipation, low cost, high reliability, but in exchange for these advantages one has to accept that the voltage on the battery is always [...]

Stereo Decoder with TDA1591 IC. [....] Link

As you probably know, to enable stereophonic broadcasting, audio channels LEFT and RIGHT have to be specificaly encoded in such a way that FM receivers can reconstruct stereo. This is a low cost, but powerful, stereo coder. Since the schematic is very ‘clean’ there’s no full documentation available. Just note that : * Trimmers adjust [...]