Wiring Schematic Diagram

Saturday, November 7, 2009

600 WATT HI-FI Power Amplifiers PA600

Attached is the schematic of a PA or subwoofer power amplifier capable of delivering about 650W RMS into 4 loads. The original design was called ’PA 600’ and was first published in the German magazine ’Elrad’ in 1990.
Towards the end of 1995, a scaled-down version of this circuit appeared in ’Elektor’ as ’PA 300’.
It is virtually the same circuit except for a less powerful output stage (now two complementary
pairs instead of five with additional driver stage) and minor changes in component selection and values. However, as ’Elektor’ is much more popular, many people built a ’PA 300’ without knowing it was scaled down from a bigger amplifier.

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Wednesday, November 4, 2009

ONE CHIP FM RADIO ( KA22429 )

The KA22429 is a monolithic integrated circuit designed for Portable FM radio.
It is consistng of RF input stage, Mixer, IF, Mute control and Loop (earphone drive) AMP.
It is suitable a pocket - size radio.

FEATURES

Minimum number of external parts required
It is able to a single trimmer tuning
No FM det coil
It is FLL detect system (76KHz)
Operating voltage: Vcc= 1.8V~6.0V

[read here...]

Thursday, October 22, 2009

STEREO FM TRANSMITTER WITH I.C. BH1417

This is the latest BH1417 Stereo Encoder design from RHOM that includes a lot of great features in one small package. It comes with pre-emphasis, limiter so that the music can be transmitted at the same audio level, low pass filter that blocks any audio signals above 15KHz to prevent any RF interference and crystal based stereo encoder for stereo transmission.

BH1417 can be supplied with 6 - 15V voltage, consumes only around 25mA while providing very sound quality and improved 40dB channel separation. BH1417 is only available in SOP22 IC case and this may be an inconvenience for some folks.

On the other hand, because the chip is smaller than regular DIP-based ICs it is possible to fit the entire stereo coder on a small PCB.

BH1417 requires 7.6MHz crystal oscillator which is pretty hard to find. The good news is that you can use 7.68 MHz crystal instead. In fact our BH1417 stereo encoder prototype uses 7.68 MHz crystal.

This has absolutely no effect on stereo encoding process, we have tested it and stereo sound is crystal clear.

Specifications:
Supply Voltage: 9 - 16V
Transmission Frequency: 87.7 - 88.9MHz, 106.7 - 107.9MHz (200kHz steps)
Output RF Power: 20mW
Audio Frequency: 20 - 15KHz
Separation: 40dB
Power Consumption: 30mA

Frequency Selection / Calibration
Frequency selection is very straight forward. Simply select transmission frequency at which you would like to transmit, set the combination for 4-DIP switch and BH1417 will immediately tune to that frequency. If you can't hear the transmitted audio signal on your FM receiver then re-adjust 2.5 turn variable coil until you can hear the signal. If you have a laboratory power supply you may try to vary the voltage supply from 9 to 16V. While doing that BH1417 will automatically vary the voltage for MV2109 or ZMV833ATA varicap diode making sure that there's no frequency drift.