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In the bowels of: TV IR Sensor


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In the photography is the remote control receiver module from a VIZIO television.
At the lower center is IR sensor and to the right of the sensor marked by red is the power on white LED.

This photography shows the output from the module  when a remote control button is pressed
and held. The burst of pulses identifies which button was pressed. Following this burst
are the Keep Alive Pulses (KAP) - my designation.

As long as a button is held down this train of pulses are produced.
Used for example when changing the audio volume. The KAP are 10.5ms wide and spaced every 107ms.


A simplified overview of a circuit I used to control a small gearhead motor. The KAP are feed to
a 555 timer (as a monostable) that produce larger positive pulses. A leaky capacitor integrates
the pulses that drive a transistor to power a DPDT relay.

The relay's NC contacts powers the motor CCW until a mercury switch switches the power off.
When a signal is received the relay switches the NO contact to closed, then the motor rotates
CW until power is switched off by a second mercury switch.

When the remote button is released the relay transitions and the motor rotates back CCW to its
starting position. The mercury switches are mounted 90 degrees apart on a disk being rotated
by the motor.


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