555 Circuits


Infra-red Light Barrier Using 555

This is a short-range light barrier for use as an intruder alarm in doorposts, etc. The 555 in the transmitter (Figure 1) oscillates at about 4.5 kHz, supplying pulses with a duty cycle of about 13% to keep power consumption within reason. Just about any infra-red LED (also called IRED) may be used. Suggested, commonly […]


Light Gate With Counter Using 555 And 4033

The circuit described here counts the number of times that an infrared beam is interrupted. It could be used to count the number of people entering a room, for instance, or how often a ball or another object passes through an opening (handy for playing shuffleboard). The heart of the circuit consists of – you […]


Voltage Controlled Switch using 555 Timer

Description: In this circuit the 555 timer is used in a novel way, as a voltage controlled switch.The old and omnipresent NE555 can be very good at something it was not meant for: driving relays or other loads up to 200 mA. The picture shows an example circuit: if the input level rises over 2/3 […]


555 Timer Clap Switch

This 555 timer clap switch circuit electronic project is designed using some common electronic parts. This 555 timer clap switch circuit electronic project operates from a distance of up to 10 meters from the microphone . Signal from microphone is amplified by transistors T1, T2 and T3. Diode D1 detects clap signals and the resulting […]


Alarm Circuit for Snoring Prevention by 555 Timer

The circuit was designed to produce a circuit that will alarm a sleeping person to prevent snoring by using a vibrator instead of an audio alert so as not to affect the whole household. It contains a trigger indicator, peak display indicator, a level control and a variable trigger threshold. A small motor enclosed in […]


555 Touch Switch Circuit

This circuit uses a 555 timer as the bases of the touch switch. You can learn more about 555 timers in the Learning section on my site. When the plate is touched the 555 timer is triggered and the output on pin 3 goes high turning on the LED and the buzzer for a certain […]


555 Timer Circuit With Variable On/Off Times

This circuit enables the on/off times of a 555 timer to be independently varied over a wide range. This is not possible with a conventional 555 circuit with the RC network being charged from the positive supply rail and discharged via pin 7. Instead, the capacitor at pins 2 & 6 of IC1 is charged […]


555 DC/DC Converter

It is all too often necessary to augment the power supply of an existing electronic circuit because exactly the voltage that you need is missing. The circuit presented here may provide a solution in a number of cases, since it can be used to convert a single-ended supply voltage into a balanced set of supply […]


555 Police siren

The Police Siren circuit uses two 555’s to produce an up-down wailing sound. The first 555 is wired as a low-frequency oscillator to control the VOLTAGE CONTROL pin 5 of the second 555. The voltage shift on pin 5 causes the frequency of the second oscillator to rise and fall.


Automatic Hand Dryer Circuit

Now and again ardent hobbyists looking to add something special and individual to their rest room/bathroom want an automatic hand-dryer. This design guide exhibits that you need barely anything more than a handful of inexpensive components and the right enclosure. Here is how to build a versatile hand-warmer at a low cost! Before you start […]