When the IR detector on the RRW1A (transmitter board) “sees” a 38 kHz IR signal, the output of the detector goes low (it is inverted). When there is no 38 kHz signal present the output idles high. On the output of the IR detector you won’t see the 38 kHz, just the data that the 38 kHz represents from your IR remote control. This data from the IR detector is then used to switch on and off a 433.42 MHz oscillator. Instead of switching an LED on and off at 38 kHz, we are now switching an electrical field on and off at a rate of 433.42 MHz. This acts as our new carrier frequency for the wireless part of the kit.
The oscillator section is a Colpitts style oscillator formed by Q2, C7, C8, R6, and X1. The oscillator is turned on and off by Q3 through resistor R4 in accor- dance with the received IR data. When a data pulse is detected by U1, its out- put goes low pulling the base of Q3 low to turn it off. When Q3 turns off, the collector (R3, R4, and Q3 junction) is pulled high so the needed bias voltage is applied to R4 causing Q2 to turned on and begin oscillating with the surround- ing parts. Turning Q2 on and off performs the
The RRW1B (receiver board) has a specialized receiver chip which is also set at 433.42 MHz. The receiver detects whether or not a 433.42 MHz field is being broadcast and only sets its data output high if a signal is present. The RRW1B will replicate the transmitted data by turning its data out pin on and off at the received data rate. To
By using this method with a
Once the
Wow! There’s a lot going on here!
RRW1A • 6