Showing posts with label Police. Show all posts
Showing posts with label Police. 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.
Friday, October 24, 2014
Police Sirine Circuit with IC 555
The series of police sirens with 555 ic this is a series of sirens that utilizes two IC 555 as a pulse generator and producing shrill voice.
Both ic 555 respectively build the astable multivibrator circuit and generate output signals with different frequencies. It is intended to be used as one of the high frequency generator or a screeching sound and the other as a regulator of the swing from last shrill voice. If we observe the working principle of this circuit is very similar to a series of modulation fm. Where the shrill sound signal likened to a high frequency signal from the oscillator circuit and control signal swing is the wail of the information signal or input signals that will transmit. This is consistent with the shape of the output signal associated with the loudspeaker, which has an output signal frequency changes in the form of regular meetings wave tenuous.
Actually a series of sirens could be simpler than if you use a 556 IC which is a dual multivibrator or equal to two pieces of IC 555. IC 556 has two multivibrator circuit menfaatkan so you can meet the workflow of this siren sound-producing circuit. Or you can also make it by using a combination of multiple transistors. And it could be you do remember the oscillator circuit can be easily made with transistors.
Appropriate image above then:
R1, R2, and C1 is a determinant of the frequency of the signal generated by IC1
R3, R4 and C3 is a determinant of the signal frequency whine
Signals generated by IC1 IC2 pin 5 connected to the control signals intended for the resulting shrieks
Screeching sound signal will swing to follow the control of the output signal IC1
You can do experiments in order to gain more understanding of police sirens this circuit by changing the value of some critical components such as the frequency of R1, R2, R3, R4, C1 and C3.
Subscribe to:
Posts (Atom)