LM317T Voltage Regulator with Pass Transistor

Using an audio transformer to boost up the audio signal and using a laser diode to transmit audio signal to a solar cell. The laser diode has it's own voltage regulator built from LM317. Audio signal originally change in term of voltage( and frequency) becomes changing in term of current( and frequency) before entering the laser diode. Current is propotional to the laser beam intensity. Subsequently, the solar cell reveicer the laser beam with a varying intensity( and frequency) and produce a audio signal change in term of voltage( and frequency). This improved version has a adjustable pre-amp which amplifier the audio signal before it reach the speaker. Using a low power Op amp LM324 instead of LM741 which only need a power supply of minimum 4VDC only. The improved version has enough power to drive a large variety of headphones and speakers wihout addition power needed. Pre-amp: Ultilizing a non-inverting amplifier configuration to prevent loading effect.



http://www.youtube.com/watch?v=jrIvOVPhtts&hl=en