Phase Locked Loop (PLL) Oscillator Circuit 860 MHz

Phase Locked Loop (PLL) Oscillator Circuit 860 MHz

This 860 MHz Phase Locked Loop (PLL) oscillator circuit is for 1200 MHz transverter's local oscillator with 435MHz rigs. The oscillator circuit uses PLL synthesizer IC's of Toshiba for PLL circuit. TC9122P is easy to use preset counter for determining request frequency value by patching. TC5081AP is phase comparator and TC5082P is binary counter for 2048 dividing. TC5082P has also been consited of Xtal oscillator circuit. 12.8MHz is divided by 2048 into 6.25Khz.

MB501 is a 64 dividing prescaler You must patch the input of TC9122P for 2150, and 6.25kHz*2150*64 comes to 860MHz. Parts VCO made by MURATA as MQC-302-856.

Circuit Diagram

The loop filter is simple lag-lead filter The output RF signal is boosted by MMIC. The uPC1675G is not suitable for this level, you may use MAR-3 instead. Because the uPC1675G's PiMAX is 0dBm and then Po:4dBm, MQC-302-856's output of 1dBm.is over power. If you use MAR-3 instead you will get 11dBm of RF output.

I would like to use this LO for 1200 MHz to 435 MHz converter and combining with TUF-5 DBM. TUF-5 asks +7.5dBm LO input for MAX conversion gain. And on the input of DBM there should be placed PAD for decreasing distortion. 11dBm output level is adequate, so I think.

Assembled Circuit

Printed Circuit Board

Local Oscillator Parts

Motor Speed Control Using PWM

Pulse width modulation or familiarly known as PWM is used to control the delivered power to load without loosing the efficiency. The speed of an electric motor is controlled by controlling the power source of the motor. The simplest method to provide a variable power supply is by providing a variable series resistance between the motor and the supply, and this is common in AC motor since the series resistance can be replaced by a series inductance that doesn’t dissipate any power. In DC motor system, this method can be done but unfortunately the inductance cannot work and we should go with a resistance that dissipate a lot of power. This power dissipation is too bad for the power efficiency since the power is wasted as heat. By using a PWM, the controller acts like a switch that is turned on and off rapidly to mimic the variable power supply without wasting the power.

Here is an example of PWM controller for DC motor, taken from freecircuitdiagram.com

Although the circuit shows a voltage range of 3-18 volts for the LM555 IC, it’s a good thing to keep the voltage range for this IC between 9-12 Volts. Below 9V, the MOSFET would not be maximally switched on, while above 12 Volt the 555 IC would be normally suffer an overheating. If the DC motor voltage is specified between 9-12 Volts then we can use the same voltage source for both 555 IC and the motor, but if the DC motor operating is higher then you sould use a separate power supply for the Motor (only the ground line is connected together). Up to 50 Volts DC motor voltage can be safely driven by this circuit