Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

Stereo Test Tone Generator

Stereo Test Tone Generator

It seves the purpose of aligning an FM Stereo Modulator used in low power FM stereo transmitters. Two tone outputs are available, the low tone has a secondary output that is 180 degrees out of phase with the primary output.
Specifications

Operating Voltage: 12V DC (should work ok on 9V)
Operating Current: 15ma max.
Low Output Frequency: approximately 600 Hz
High Output Frequency: approximately 800 Hz
Output Levels: approximately 0.5V – 5V P-P

Theory

IC U3B is wired to produce a virtual ground at half of the power supply rails (6V). This is used elsewhere in the circuit as a reference. The power supply is filtered with the 220uF capacitor. The 3A diode offers some protection against reverse polarity on the power inputs. For full protection, place a 1A or smaller fuse in series with the +12V input.

The circuit has two nearly identical stereo sine wave generator circuits. U1 is the heart of the low tone oscillator, U2 is the heart of the high tone oscillator. The two op-amps on the left of each oscillator chain produce square and triangle waveforms at fixed frequencies. The frequency is set with the 10n and 6n8 capacitors.

The triangle waves are passed into low-pass filters, which remove most of the harmonic energy and produce relatively pure sine waves. The two 27K and two 33K resistors set the low pass frequency.

The sine waves are each fed into an output amplifier which can be adjusted for fixed level outputs. The low tone output is also fed into IC U3A which produces an inverted copy of the low tone signal.

Visit Here for more.







 

More Articles to Read

Design for a Wideband, Differential Transimpedance DAC Output
Design for a Wideband, Differential Transimpedance DAC Output
Wrist thrusters let you fly through the water effortlessly
Wrist thrusters let you fly through the water effortlessly
Bertan/Spellman 225-20R HV power supply teardown
Bertan/Spellman 225-20R HV power supply teardown
Blinking Christmas Lights
Blinking Christmas Lights
Adjusting clock with alarm, hygrometer & thermometer on 1.8″ ST7735 display
Adjusting clock with alarm, hygrometer & thermometer on 1.8″ ST7735 display
Adding an “extra sense” with rangefinders
Adding an “extra sense” with rangefinders
This wireless game controller looks like a rug
This wireless game controller looks like a rug
How to run your ESP8266 for years on a battery
How to run your ESP8266 for years on a battery
Calibration of a 3-Phase Energy Meter Board on the ADE7754
Calibration of a 3-Phase Energy Meter Board on the ADE7754
Making beats on a tiny Arduino DJ controller
Making beats on a tiny Arduino DJ controller
Qinsi-QS5100 Sn63Pb37 solder profile
Qinsi-QS5100 Sn63Pb37 solder profile
Water Detection System
Water Detection System
Professional Hi-Fi 15W Tube Amplifier circuit
Professional Hi-Fi 15W Tube Amplifier circuit
This Arduino machine will judge how sick your ollies are
This Arduino machine will judge how sick your ollies are
Turn an old payphone into a boombox for ’90s hits
Turn an old payphone into a boombox for ’90s hits
Big F’n 3D printer build
Big F’n 3D printer build
Temperature alarm for boiling milk
Temperature alarm for boiling milk
QuadBot is a 3D-printable walking robot for everyone
QuadBot is a 3D-printable walking robot for everyone
MicroConverter I2C Compatible Interface
MicroConverter I2C Compatible Interface
An Arduino tachometer for your older vehicle
An Arduino tachometer for your older vehicle

Top


Shares