2B-ADJUSTABLE TIMER WITH ON/OFF
The OFF and ON time of this project can be set as per your requirment. The OFF time can be more or ON time may be less and vice – versa. You can attach this project to your ALL-OUT Mosquitto repeller to control the comsumption of liquid. By this you can save more than Rs. 300/- per year.
TECHNICAL DESCRIPTION AND WORKING
This project has been developed and tested O.K. in our TV Engineers Technical Lab. The components and PCB used in the projects published in our books are available for sale at resonable price.
This project, based on timer IC 555, is a simple and economical one. We can control its ON/OFF time through the preset connected to the circuit. A discharge capacitor is connected across pin no. 2 and 6 of the IC 555 and these pins are connected to pin no. 7 through two presets and two diodes are connected in forward and reverse mode. When the information at the output pin no 3 is in high state, the discharge pin remains cutoff. The relay remains ON as the capacitor is charged. When the output again become low, the capacitor starts discharging and the relay becomes OFF. The ON/OFF timing can be adjusted by the pre-set.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT:-
*Check polarity of electrolytic capacitor while mounting on PCB otherwise reverse connection may damage it.
*Check the polarity [ Anode & Cathode] of Diodes before fitting.
*Clean PCB after soldering, so that the component or print do not short.
*While mounting transistor, you should connect collector , base & emitter properly.
*First of all check all the components as per circuit.
4.7K = 1
1K = 1
2.2M = 2
IN4148 = 2
IC 555 = 1
RELAY 9V = 1
BC148 = 1
2200MFD/25V = 1