Ramsey Electronics FM25A Bedienungsanleitung PDF herunterladen (Seite 4)

Circuit Description

Power Supply

The AFeL DC power supply is originally provided as a part of the

Ramsey™ FM-25A kit.

While a DC power source is provided with the

FM-25A, the DC isn’t proper enough to provide us with the low-noise,

stable supply that we would like for a good audio quality. The Voltage

Regulator VR3 provides us with the means to take the raw DC output from

the wall transformer and smooth it out, keeping it at a constant 12 volts.

USB

The USB provides the communication between the PC User interface

(software) and the PIC microcontroller (hardware). The USB tells the PIC

which hardware component to turn on/off and what frequency to use. The

USB returns a ‘go’ or ‘no-go’ information form the PIC to the PC. The USB

has four Pins: Power, ground, D1 & D2 used to pass and receive data.

Microchip™ PIC16745

The Microchip™ PIC16745 microcontroller is the brains of the transmitter

and receiver. The PIC tells the transmitter and receiver when to turn on or

off and what station to transmit or receive. Without the PIC, the transmitter

and receiver would do nothing. The PIC, upon power-up, sets the PLL of

the transmitter then configures and initiates the USB. The frequency is set

to the Transmitter and transmission will begin. Please refer to the PIC

schematic for input/output specific pins.

Receiver

The Receiver is used to scan the licensed FM band (88-108 MHz) in order to

detect an open, or unused frequency. The components in the diagram

consist of the front-end chip, receiver chip and the PLL chip.

Note: Technical/Use information concerning FM25A kit taken directly from Ramsey™ User Manua

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Ramsey Electronics FM25A Bedienungsanleitung Seite 4