Electronic schematics, circuit designs
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 schematic.
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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 receiver schematic
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 is relative directional and can be improved by placing the leds in different angles and placing reflectors behind them.
The optimal input audio level is 100 - 200mV for 1.2 - 2.4 m coverage of this head phones ir transmitter.
On the site we provide the infrared receiver schematic for this infrared headphones tx.
