LM317T Voltage Regulator with Pass Transistor

Read Here: I have several previous videos that lead up to this video about simple and cheap laser communication. The system up to this point shown in the video works great for transmitting audio/sound/music via a laser beam. Give your friends a reciever to put in their window and you can transmit some audio to them, as long as they are within range, line of sight and/or mirrors can "bend" the laser beam. Unlike other methods of communication, no transmission wires, license or other hassles come with this method. Disclaimer: There is no need to look into the direct laser beam since it can damage your eyes or someone elses. Still, if complete sound input isolation is needed from the laser communicator circuit, you can try a 1 to 1 transformer, or two 8 to 1000 ohm ones connected together to where the primary is 8 ohms and the final secondary is 8 ohms. If you cant find or contruct a 50K fixed resistor, you can just use a more common 47K resistor. I think it's better to have some adjustability to Rb for various reasons. So then, perhaps a 50K variable in series with say 33K (to prevent your pot from getting dammaged, etc) or something. The next step is to transmit and successfully receive digital computer data with the laser communicator system. I will try the KCS (Kansas City Standard) scheme, but there are others, and I'm not sure what would work the best, assuming at least one method will work though. The clothespin attached to the laser is to apply pressure like a clamp ...



http://www.youtube.com/watch?v=9QKgSeiBwdU&hl=en

Using a high power laser with a voltage regulator to performance a long range audio signal transfer. In the test, due to the limitation of my room, it is actually a short range. This is the first test for the circuit. I will make some adjustments on the circuit design and perform a long range test later. Enjoy. (?) ***** Notice, you may need to increase your headphone or speaker volume to hear the result. *****



http://www.youtube.com/watch?v=Y9Zez7Ypt8E&hl=en

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