Categories: AlarmFun CircuitsMisc

Adjustable Analog Timer


This is a very simple adjustable analog timer circuit diagram. You can build this circuit just for fun, for newbie project or may be…, this circuit could be used to set a time limit when playing games or as an egg-timer in the kitchen.

The circuit will start timing when switched on. The green LED lights to display that timing is in progress. Once the period of time is finished the green LED gets off, the red LED gets on and therefore the bleeper sounds. The interval is set by altering the potensiometer and it could be altered from 1 to about 10 minutes (approximately). Please note that the range of time intervals is only approximate. With ideal parts the maximal time period ought to be 4? minutes, but this is usually extended to about 10 minutes since the 220uF timing capacitor gradually leaks charge. This is actually a problem with all electrolytic capacitors, but some leak more than others. Additionally the real value of electrolytic capacitors can vary by as much as ?30% of their rated value.

Component needed for this adjustable analog timer:

  • resistors: 470, 33k, 100k
  • variable resistor: 1M
  • capacitors: 0.1uF, 220uF 16V radial
  • LEDs: red, green
  • 555 timer IC
  • 8-pin DIL socket for IC
  • on/off switch
  • battery clip for 9V PP3
  • bleeper 9-12V

Download this project in PDF file:
Adjustable analog timer project

circuit schematic

Share
Published by
circuit schematic

Recent Posts

Switched ON Bike Lamp

Do you have a bicycle..? why don't try to build this circuit..?. Powered using battery…

54 years ago

3A Switching Power Supply Regulator

This is the circuit diagram of 3A switching power supply regulator: Simple and cheap, the…

54 years ago

Remote Control Tester

Here is the remote control tester circuit. This circuit is really a simple and easy…

54 years ago

Current Output Multiplier for 78xx Regulator

This is the circuit diagram of current output multiplier designed for regulator IC LM78xx. By…

54 years ago

4 Transistor FM Tracking Transmitter

The following diagram is the FM tracking transmitter based on 4 transistors. No additional notes…

54 years ago

White Line Follower

This is the circuit diagram of white line follower toy. The actuator of the toy…

54 years ago