Circuit-Zone.com - Electronic Projects

SAA1057 PLL Synthesized FM Transmitter
Posted on Friday, April 30, 2010   •   Category: FM Transmitters

SAA1057 PLL Synthesized FM Transmitter

The functioning of all is provided by a microcontroller from MICROCHIP "PIC16F84" which provides support for buttons, LCD 2 lines of 16 characters and the circuit pll "SAA1057. The VCO is entrusted to the transistor Q8 associate of his two diodes varicaps "BB109, a floor buffer Q7 separates the VHF signal obtained in two ways, on the one hand to Q9 to enslave loop phase and on the other hand to the Q5 and Q6 together which takes care to amplify the signal before attacking Q11, a "BFR96" which plays the role of HF switch via a timer "NE555" which receives information from the push and "SAA1057" ensuring HF cutoff in the event of failure of a locking or unlocking of the pll.

40MHz Frequency Counter Module
Posted on Friday, April 30, 2010   •   Category: Test and Measurement

40MHz Frequency Counter Module

This circuit is ideal for adding a low cost frequency display to a function generator or other design. I doubt if it is possible to get a cheaper design using off the shelf components!. In fact, I challenge anyone to make a cheaper design using garden variety components!. The upper frequency limit is dependent upon the upper limit of the 74HC390 chips which is roughly 40MHz.

USB RDS Coder Board using ATmega32
Posted on Friday, April 30, 2010   •   Category: AVR

USB RDS Coder Board using ATmega32

This board is a RDS coder using an ATMEL AVR ATmega32. This board can be controled by a RS232 link, USB interface or SPI. TA data is displayed wiyth a LED and can be controled by : - Hardware input - RS232 - USB - SPI (not yet implemented)

Low Pass Filter For FM 88-108 MHz
Posted on Friday, April 30, 2010   •   Category: FM Transmitters

Low Pass Filter For FM 88-108 MHz

Filter used for eliminate unwanted harmonic frequency at second and third. Notch filter, Band Pass Filter (BPF), and High Pass Filter (HPF) sometime combined in constructing LPF design. Schematic below for FM Broadcast Lowpass Filter 88-108 MHz. It has been tested with a good result. Note : Make the coils at 74 nH and trim them to adjust exact value.

FT232 USB Interface Adapter
Posted on Thursday, April 29, 2010   •   Category: USB Interface Adapters

FT232 USB Interface Adapter

Control up to three devices from a PC with FT232 IC (USB to Serial UART) from Future Technology Devices International FTDI. Circuit is simple and does not require external microcontroller or any type of firmware programming. PC control software written in VB6 is included.

USB DS1820 PC Thermometer
Posted on Thursday, April 29, 2010   •   Category: PIC

USB DS1820 PC Thermometer

This is a digital thermometer based on USB PIC16C745 microcontroller from Microchip and DS1820 sensor from Dallas Semiconductor. Temperature readings are sent over USB port in HIDCOMM USB mode to VB6 program on a PC. Hex program and sample Visual Basic 6 application is included.

MC145170 PLL FM Transmitter
Posted on Thursday, April 29, 2010   •   Category: FM Transmitters

MC145170 PLL FM Transmitter

In order to simplify the transmitter design, we've used the new pll circuit from Motorola :the MC145170. This PLL includes the prescaler and a serial standard bus called SPI.

Temperature / Light Brightness Meter with LCD
Posted on Thursday, April 29, 2010   •   Category: PIC

Temperature / Light Brightness Meter with LCD

Circuit measures the temperature and ambient brightness of the surrounding environment at the location it is placed. The data from the ADC is the calculated and displayed on the LCD. The main CPU unit on board the device is the PIC16F873.

Infrared Remote Volume Control
Posted on Thursday, April 29, 2010   •   Category: Remote Control

Infrared Remote Volume Control

This is a true 'minimalist' remote, having but three functions: Volume Up, Volume Down and Mute Volume is controlled by a motorized (motorized for US readers) pot rather than any of the 'digital' pots that now abound, and this was done for a number of very good reasons.

19 KHz MPX Low Pass Filter
Posted on Wednesday, April 28, 2010   •   Category: FM Transmitters

19 KHz MPX Low Pass Filter

This map, armored also enables automatic MONO / MPX through a low-pass filter, even with a multiplex on its entry by using an ON / ON, panning, the whole spectrum MPX more RDS is sent to the synthesizer, on the other hand when it is in a position MONO, the low-pass filter is activated and share its cutoff frequency at 15 KHz, only modulation G + D is sent to the synthesizer, as 19 KHz. 19 KHz carrier, the signal multiplex and subcarrier 57 KHz is thereby eliminated, which provides ease of use for example in a string of issue relay tuner, if the link between the issuer Departure and receiver re-issue was not of good quality stereo, you sufficient to switch to mono to improve sound quality, you can then connect the RDS encoder at the re-issuer.

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