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IR Heart Pulse Monitor :  Reverse engineered circuit diagram of a pulse sensor circuit board out of a treadmill. Notice that the output is level shifted for use by CMOS logic running on 4.5V regulated down from the 6V battery. The CMOS logic also controlls the power to the analog circuitry and infrared LED. I do not gaurantee the accuracy or safety of any information herein.
(added 2/05)

IR Link #2:  A basic Imfra Red Link for audio communication for distances upto 3 metres (added 6/03)

IR Link:  (electronic circuit added 7/03)

IR Localtalk Link has Superior Range and Ambient Rejection:  DN118  Design Notes (Linear Technology) (app note added 1/06)

IR Modulation Detector:  A circuit to extract and measure the modulated carrier of an Infra Red remote control. Note that the circuit does not physically separate control pulses from modulation, but amplifies the completereceived signal allowing the waveform to be displayed ideally on an oscilloscope or a frequency counter. Modulation frequencies between 1kHz and several MHz may be measured.  (added 10/05

IR Remote Control Extender Circuit (Mark 2):  (electronic circuit added 7/03)

IR Remote Control Extender Circuit (Mark 3):  (electronic circuit added 7/03)

IR Remote Control Extender:  (electronic circuit added 7/03)

IR Remote Control Jammer:  (circuit / schematic design added 11/06)

IR Remote Control Tester #3:  (electronic circuit added 7/03)

IR Remote Control Tester:  (circuit / schematic design added 6/06)

IR Remote Control:  (electronic circuit added 4/05)

IR Remote Switch:  (electronic Circuit / Schematic added 10/04)

IR 'Slotted Switch' Sensor:  ASCII format (added 4/02)

IR Transmitter Circuit:  (electronic circuit added 4/05)

IR-Linked Temperature Sensor:  App Note 3457: Maxim IC  (application note added6/06)

IR-Related ASCII Schematics V1.00:  (circuit / schematic design added 6/06)