HOW THE URC1 WORKS:
Take a look at the URC1's schematic diagram as we walk through the circuit. As you can see there is not much to the universal remote control, most of the work is internal to the IC's.
The real heart of the circuit is U6 the microcontroller IC. This 20 pin IC can perform an amazing amount of tasks, quickly as well as reliably. This IC controls all of the outputs as well as the display, and also processes the codes decoded from U5, the tone decoder IC.
U5, the tone decoder IC does most of the complicated work in this kit. Internally this chip has a set of counters that latch different outputs depending on the tones. The internal counters are referenced to a television colorburst crystal operating at 3.579 Mhz. This reference frequency is used also as the clock frequency to pin 10 of U5 the microprocessor.
U1, and U3 are serial shift registers. Data is clocked into them bit by bit from the microprocessor, and then latched to the outputs by a change in state on the LDS line. One of the outputs from these chips is used to deliver a tone output for confirmation of commands.
U4 is a digitally controlled dual potentiometer. A very versatile device, it can control volumes, levels, tuning on most Ramsey kits, thermostats, and whatever else a pot can be used in.
U7 is a quad serial digital to analog converter. This provides the
U2 is the display driver IC, this is also loaded serially with information to what the displays show. It controls six digits of the display as well as the error code LEDs.
VR1 and the surrounding parts form a simple voltage regulator to supply a steady 5 VDC to the ICs in this circuit. By using this scheme, we can have a wide range of supply voltages, from 7 volts to 15 volts DC.
URC1 • 5
