Showing posts with label ne555. Show all posts
Showing posts with label ne555. Show all posts
Friday, November 14, 2014
POLICE SIREN USING NE555
A lot of electronic circuits using NE555 timer IC are already published here and this is just another one. Here is the circuit diagram of a police siren based on NE55 timer IC. The circuit uses two NE555 timers ICs and each of them are wired as astable multivibrators. The circuit can be powered from anything between 6 to 15V DC and is fairly loud. By connecting an additional power amplifier at the output you can further increase the loudness.
IC1 is wired as a slow astable multivibrator operating at around 20Hz @ 50% duty cycle and IC2 is wired as fast astable multivibrator operating at around 600Hz.The output of first astable mutivibrator is connected to the control voltage input (pin5) of IC2. This makes the output of IC2 modulated by the output frequency of IC1, giving a siren effect. In simple words, the output frequency of IC2 is controlled by the output of IC1.
Circuit Diagram
Notes
- The circuit can be assembled on a Perf board.
- I used 12V DC for powering the circuit.
- Instead of using two NE55 timer ICs, you can also use a single NE556 timer.
- NE556 is nothing but two NE555 ICs in one package.
- Refer the datasheets of NE555 and NE556 to have a clear idea.
- Speaker can be a 64ohm, 500mW one.
Saturday, September 13, 2014
Fire Alarm using NE555 and temperature sensor
This is a simple series of fire alarms. In this series used NE555 timer and temperature sensor to detect high temperatures. The working principle of this temperature sensor that is when the temperature is high around the sensor then there is resistance on the sensor to be small.
However if the low temperature then the resistance will be high. If the resistance of small sensors, the voltage supply will be able to flow past the sensor and activate the transistor.
IC1 NE555 as a regulator of the audio frequency. Transistors 1 and 2 are used as a driver IC1. Output (pin 3) of IC1 would trigger a transistor base T3 (SL100), which drives the speaker to produce sound the alarm. Frequency NE555 depending on resistance values of R5 and R6 and the capacitance sensor C2 temperature. When the temperature gets hot, would provide a low resistance so that supply voltage can flow into the base of transistor T1 through a diode D1 and R2.
Capacitor C1 will charge a positive voltage so that it will increase the time when the fire alarm. The greater the value of C1, the greater the positive bias applied to the base of transistor T1 (BC548). T1 collector coupled to the base transistor T2, transistor T2 provides a positive voltage to pin 4 (reset) from IC1 (NE555). Resistors R4 will make IC1 NE555 continued to be active despite no positive voltage flowing.
Wednesday, August 20, 2014
Touch Switch using NE555
The series of touch switch or touch switch is built by IC NE555, a series of touch switches can be used to turn on lights, alarms or other electronic equipment.
This circuit uses 2 pieces of metal plate media as touch, MP1 (Metal Plate 1) and MP2 (Metal Plate 2). Touch switch circuit is equipped with a visual LED indicator for relay status (load active). To enable (Relay ON) can be done by touching the surface of MP1 and to turn it off by touching the surface of the MP2. MP1 and MP2 in touch this switch can use a small piece of copper (diameter 5mm) was enough.
This circuit uses 2 pieces of metal plate media as touch, MP1 (Metal Plate 1) and MP2 (Metal Plate 2). Touch switch circuit is equipped with a visual LED indicator for relay status (load active). To enable (Relay ON) can be done by touching the surface of MP1 and to turn it off by touching the surface of the MP2. MP1 and MP2 in touch this switch can use a small piece of copper (diameter 5mm) was enough.
Touch Switch series with NE555.
Component List 555 touch Switch
R1 = 3.3M
R2 = 3.3M
R3 = 10K
R4 = 1K
C1 = 10nF-63V
D1 = 1N4007
D2 = Red LED
Q1 = BC547
IC1 = NE555
RL1 = 12V Relay
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