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Welcome to the CyBENCH Project Pages - 4bit RF remote


Part 3 - Adding power leads and Test leds

The alarm used to have an internal voltage regulator circuit - until we ripped it out.
This used to generate an interal power supply rail of about 10V.

We will directly provide a 9v supply from a PP3 battery.

To do this:

1. Connect Pin 8 of IC4 to +9v of the battery, red wire on a PP3 battery snap.

2. Connect Pin 4 of IC4 to 0v of the battery, black wire on a PP3 battery snap.

Power wires

Test leds

If you wish, you can build a simple tester using four 1k resistors and 4 led's








I needed to do this to prove the system as I hacked it together.

An alternative solution would by to use the 5mm red led that is provided on the flying lead.
Simply connect the black wire to a suitable 0v connection (picture below)
Then use the striped wire to probe the data output pins of the decoder.

NOTE: This is a flashing led with an internal resistor in the cable assembly


0v connection for the test led (black wire)


Test Led in use



TESTING:

When you first power the alarm unit up, no leds should illuminate.

When you press the Disarm button on a keyfob, two leds should light:

br>When you press the Arm button, three leds should light:


When you press both buttons together, all leds should light:


At this stage, there is no way to control the two leds connected to pins 12 and 13 of the decoder.