Development in electronics has played a major role in today world. Due to this we are able to utilize the Electricity properly and saving of the Electricity also is possible. Present project can be used for toilet light or Tares Light because there are chances that we forget to putoff the light at such places.


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 is a new edition of Electronic world. The main attraction is that it is transformerless and you have to put switch ON only once. Where as normally we have to use two way electrical switch. One in the lower floor and second on the upper floor and if light remain ON unnecessary, electric energy is wasted. With this project all these problems are solved. In this project IC 555 is used as monostable oscillator. In this IC No 2 is a trigger pin and output is available at pin No 3. Pin No. 7 is the discharge Pin whereas pin Nos. 6 is threshold Pin . Control Voltage Pin No 5 and Pin 4 is the Reset Pin which is normally kepts high . When anybody put the switch ON a Negative going Pulse flows pin No 2 and timer is trigger. Due to this Capacitor connected at Pin no. 6 & 7 get charged. When Charged Capacitor voltages reaches about two third of positive supply’ the timer gets off. To increase the period of timer ,the value of capacitor is increased.  A condenser of 0.1 mfd is connected to the pin no. 5 and earthed . It gives the control voltage.  Power supply unit consists of 10K \ 10W resistance ,diode IN4007 and a 12V Zeener diode, It converts the AC into DC. A triac is employed to operate the load .

When gate of triac gets triggering voltage then a bulb used as load gets lighted and timer is off after the fixed period.


Precautions while ASSEMBLING THE PROJECT :-

This project operates on AC mains , so don’t touch with bare hands when power is on .

Do’not use load more than 100Watts in this project, for more load use triac of higher capacity

Take care of polarity of condenser soldered at Pin no.6 of IC 555

Do’not solder the IC directly on PCB. There is possibility of parts getting spoiled due to leakage current from the soldering iron


PCB [Code 5TP10]=1


10K=1, 10K/10WATT=1, 220E=1, 1MEG Tone=1


1000mfd/25V =1, 220mfd/16V=1, 0.01mfd=1


IC555 =1, BT136=1, IC Base [8 pin]=1, 12 Volt Zeener =1, IN4007 =1, Push To ON Switch=1


Cabinet =1

Bulb 60 Watt =1