Dilshan R Jayakody’s Web Log

This is contactless DTMF ( Dual Tone - Multi Frequency ) switch to control 16 channel relay boards. This module can turn ON/OFF relays based on DTMF singles which captured from its microphones. This project is building using 4 commonly available ICs which including TL084, TL081, CM8870, and 74LS154. TL084 is used as microphone preamplifier and LPF. TL081 act as combiner and CM8870 is used to decode the DTMF inputs. 74LS154, the demultiplexer is used as line selector. In this circuit TL084 and TL081 and replace with any compatible operational amplifier IC. During our prototyping, we replace TL084 with LM324, TL074, and TL081 with TL071 and got identical results. For the microphones, it is highly recommended to use omnidirectional condenser microphones. In our tests, we get good results when both the microphones are in the 90⁰ plane. This circuit is design to work with single rail 5V DC power source and its output terminal ( SV1 ) is compatible with most of the 16 channel relay bo...

This is an ATmega32 based Proteus simulation of 16 line connectivity tester. I mainly did this project to get familiar with the new Proteus 8 simulator (mainly the new Proteus  - ISIS module). The main functionality of this system is to detect open and short circuits in cables and connectors. This system can test maximum of 16 lines in each test cycle and it indicate the defective line(s) through LCD. This is customizable system and user can configure number of test lines through single push button (SW1). The ATmega32 firmware is developed using WinAVR toolset and it design to work with both simulation and real modes. Schematic of 16 Line Connectivity Tester I never test this system with real parts. If someone interested about real implementation make sure to change RN1 and RN2 to 22K and diode array with 16 - 1N4148 diodes. Recommended supply voltage for this system is 5V DC. This is an open hardware Project and this work is licensed under the Creative Commons Attr...