This PLL has been designed with an old Motorola circuit :the MC145151. The VCO is based on a "Colpitz" oscillator equiped with a Fet Transistor.(J310) Two varicap Diodes are used in order to reduce the global noise of the VCO. In addition,these two diodes allow the PLL to keep the lock status through a large range of climatic conditions. An another J310 is used in order to match the impedance between the oscillator and the fist amplifier stage. A MSA1105 from Minicircuits increases the RF power level coming from the VCO to +14dBm. A simple low pass filter rejects the second harmonic to -20 dB.(Worst case) Finally, a 7 dB attenuator and a second amplifier stage (BFR96S) achieve this radio design.

The encoder/decoder parts are to be connected to a transmitter/receiver module which takes care of the transmission of digital signals by radio or infra waves. The communication signal format is designed to be used for radio transmission (it has a constant 50% signal/silence ratio), but it can work with infrared devices as well.

Voltage range: 0.7 - 24V Current limiting range: 50mA - 2A A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist's workbench. This circuit is not an absolute novelty, but it is simple, reliable, "rugged" and short-proof, featuring variable voltage up to 24V and variable current limiting up to 2A. Well suited to supply the circuits shown in this website. You can adapt it to your own requirements as explained in the notes below.

You can construct your own long range infrared (IR) wireless remote using Motorola's MC145026 emitter and MC145027 detector chips. With your remote you can control devices up to 20 feet (7 meters) away. It operates similiarly to a TV remote. You just point the emitter at the detector, push a transmit button. The detector then interprets your data signal. You can use this circuit to remotely turn on/off devices (like a motors, relays, home appliances).

This small realization, based on one of the most common IC (MAX232) is designed to create a small and convenient TTL to RS232 and vice versa converter. All you need is 4 caps, one IC and 2 connectors. If you want to add a small regulator on the board (already foreseen on the PCB) you just need to add a 78L05 regulator and a cap.

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