Audio Kits
Automatic Gain Control - Volume AGC
The schematic we propose offers a less harmonic signal and a supplementary gain, so it get rid of those annoying variation between speech and music wich offen appears at radio and tv. This automatic gain volume control schematic need a +-15V power supply and 6mA.
Bellow you get the volume agc circuit pcb, graphic and [...]
Infrared headphones receiver
Use this infrared headphones receiver with the ir headphones transmitter.
Use 600Ω headphones. BPW41N and BP104 have a filter for visible light and are centered on 950nm at 250C. At normal light illumination and 3 to 4 meters distance the audio distorsion were 1 - 2%, wich is not bad for such a simple ir headphones [...]
Infrared headphones transmitter
The transmitter offers a optical link (infrared) for headphones. Three infrared leds (ir) are polirised by T1 current, P1 is used to adjust the current level . Current consumption of this headphones infrared transmitter is about 60mA at 9V. Maintain separated adapter ground and audio signal ground to prevent current reactions thru LED.
The optical link [...]
