Dilshan R Jayakody’s Web Log

The 1750Hz tone bursts are often used to trigger repeaters. There are several methods to build 1750Hz tone generators which including TC5082 divider , using MCUs, etc. In this post, I present another 1750Hz tone generator which I built using 74HC4060 high-speed 14-stage binary ripple counter and 7.168MHz crystal. In this design, 74HC4060 is used to drive the crystal and divide its output by 4096. By using 7.168MHz crystal, this circuit produces 1750.0Hz square wave output with a 50% duty cycle. A prototype version of the 1750Hz tone generator. This circuit is extremely simple to build, and I construct my prototype using a breadboard. I tested this generator by connecting its output to my Baofeng UV-5R handheld transceiver and it gives an excellent result. The key motivation to build this generator using 74HC4060 is, because of its common availability. Most of the tone generators which I found on the internet are built using MCUs or by using rare ICs, because of that rea...

Dual-tone multi-frequency ( DTMF ) is a common signaling system used in telephone networks and other communication devices. It uses a mixture of two sine waves to generate tones which represent ten digits, the letters A to D , and the symbols # and * . While I’m examining other Arduino based DTMF generators I noticed most of the designs are based on Holtek HT9200 DTMF generator IC. After a couple of experiments, I figure out that Arduino itself is capable enough to generate DTMF tones without using any external IC or generator. Prototype assembly of the ladder circuit. The design which I explained in this article is based on R-2R ladder DAC. I did this design using Arduino Uno board and still this library support only for this board. But it can easily extend to other AVR MCU based Arduino boards. Schematic of the DTMF generator. The R-2R ladder is attached to the PORTD of the MCU which is Digital out 0 to 7 in Arduino Uno board. In this design, I used 100 Ω and ...

" Musical trees " is a part of creative art installation and this project is capable to produce different audio tones by detecting a human touch to its attached plants. The existing version of this driver is capable to monitor 8 plants and produce different sounds for each plant. A prototype version of "Magic Tree" project with 2 plant samples. This project is built around PIC16F628A 8-bit microcontroller and PT2399 echo processor IC. To drive the sensor electrodes we use pair of CD4011 quad 2-input NAND gate ICs. This prototype uses TDA7052 1W audio amplifier IC to drive the speaker(s). The existing firmware of PIC16F628A is designed to produce tones in between 155Hz to 1244Hz and this range can be changed by modifying the supplied firmware source code. In this design, the PT2399 echo processor IC is used to get the more natural (/ deep) sound effect by adding some reverberation to the output. Schematic and firmware of this project are available to ...