Flip-Flop control using LDR. Sensor Circuit 10

IC 555 has an internal Flip-Flop and its working determines the output state of the IC. The discharge input of the IC has an NPN transistor with open collector. The On/Off of this transistor also depends on the state of the Flip-Flop. The Flip-Flop is under the control of the lower and upper comparator of the IC which can be independently controlled by external voltage. Here two LDRs are used for controlling the comparators.

Continue reading “Flip-Flop control using LDR. Sensor Circuit 10”


Corridor Lamp. Sensor Circuit.7

A Simple White LED Lamp to give light in Corridor or Staircase during night. It saves energy considerably since Zero watt (Not Zero but 15 watts) or CFL (minimum 5 watts) is usually used in such places. The White LED lamp automatically turns on when the ambient light reduces below the set level. It can give sufficient light in a confined area. The circuit is provided to familiarize the working of AND gate IC 7407.

Continue reading “Corridor Lamp. Sensor Circuit.7”

Movement Detector. Sensor Circuit.4

Here is an LDR based movement detector for day time use. It is highly useful in shops, banks etc to confirm the entry and exit of persons. It uses two LDRs and the popular timer IC555.

Continue reading “Movement Detector. Sensor Circuit.4”

Morning Alarm. Sensor Circuit.1

This LDR based alarm can be used as wake up alarm. The Alarm turns on in the morning automatically and turns off only when manually switched off ,so you will have to wake up. It is a simple LDR based light sensor circuit.

Continue reading “Morning Alarm. Sensor Circuit.1”

Automatic Porch Light. Utility Gadget.14

Here is a simple Automatic Porch light controlled by an LDR and Triac. It automatically turns on in the evening and turns off in the morning. The circuit is too simple and uses Mains voltage directly. It can be enclosed in a plug in type adapter box.
Continue reading “Automatic Porch Light. Utility Gadget.14”

Night Active Relay. Utility Gadgets .13

Now you can light your home premises with this Automatic lamp. It turns on in the evening and turns off in the morning. No switch and no manual operation. So it can light the premises even if the inmates are not in home. A simple security measure.

Continue reading “Night Active Relay. Utility Gadgets .13”

Peak Hour Timer. Utility Gadgets.3

This is one of my most attracted Circuit published in Electronics for You Magazine September 2008 issue. The circuit is doing a great job. It automatically cut off the Fridge during the Peak hours from 6 pm to 9 pm saving lot of energy and money. After the peak hours, the Fridge will turn on automatically. Try it and  avoid the task of manually switching off the Fridge every day during peak hours.

Continue reading “Peak Hour Timer. Utility Gadgets.3”