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Single Chip Two-Tones Siren
Kids like the police or fire-brigade cars siren sound. This circuit can generate dual tone like Police or Fire-brigade cars siren sound. This circuit usually..
This LM3909 circuit produces a rapidly rising wail upon pressing the button, and a slower "coasting down" sound upon release. If it is desirable to have the tone stop sometime after the button is released, an 18-k © resistor can be placed between pins 8 and 6 of the LM3909. The sound is then much like that of a motor-driven siren, National Semicon
10 W AUTO ALARM SIREN
Generates force field of high-intensity sound inside car, painful enough to discourage thief from entering car after tripping alarm switch by opening door. Circuit produces square-wave output that sweeps up and down in frequency. Modulation is provided by triangle waveform generated by R1, D1, and C1. If sweep-frequency siren is prohibited, remove
FIRE SIREN USES FLASHER
Low-drain circuit operating from 1. 5-V cell uses National LM3909 flasher IC to simulate fire-alarm siren. Pressing button produces rapidly rising wail, with tone coasting down in frequency after button is released. Sound from loudspeaker resembles that of motor-driven siren. Volume is adequate for child`s pedal car. -P. Lefferts, Power-Miser...
Circuit used in Dietz siren-light police-car system gives distinctive tones. Position t of S1 produces slow continuous rise and fall. Position 3 produces fast rising and falling tone. Position 2 rises slowly to full pitch when point 1 is grounded, then decays at same rate when point 1 is ungrounded. Position 3 gives most noticeable tone for break-
LOUD BIKE SIREN
Uses 5558 dual opamp and four general-purpose NPN transistors to generate triangle wave that can be distorted by 10k symmetry control to give either fast or slow rise for sawtooth applied as base bias to astable MVBR Q1-Q2. Drain is reasonably low with 9-V radio battery, Repetition rate can be varied from long wail to rapid warble, and volume...
Tone is made adjustable by using multiposition switch to change capacitors in oscillator circuit. Speed (rate of change in frequency) of siren is adjusted with R3. 4700-ohm resistor in series with R3 keeps siren op-erational when R3 is rotated to minimum-resistance position. Siren is operated by pressing switch to produce rising wail, then releasi
POLICE SIREN USES FLASHER
Low-drain circuit operating from 1. 5-V cell uses National LM3909 flasher ICs to simulate "whooper" sounds of electronic sirens used on some city police cars and ambulances. Two flashers are required for generating required rapidly rising and falling modulating voltage. Transistor is connected as diode to force ramp generator of IC to have longer O
TWO TONE SIREN
Two NAND gates are used for the oscillator, and two as the control. If the two-tone speed needs to be altered, the 220 F capacitors can be changed (larger for slower operation). If the frequency of the oscillator is to be changed, the 0. 2 and 0. 1 F capacitors can be varied and the value of R1 can be increased. To change frequency range between
SIREN ALARM SIMULATES STAR TREK RED ALERT
The signal starts at a low frequency, rises for about 1. 15 seconds to a high frequency, ceases for about 0. 35 seconds, then starts rising again from a low frequency, and so on ad infinitum.
HIGH POWER SIREN
IC1a and IC1b are wired as a slow astable multivibrator and IC1c-IC1d are wired as a fast astable. Both are "gated" types, which can be turned on and off via PB1. The output of the slow astable modulates the frequency of the fast astable, and the output of the fast astable is fed to the external speaker via the Q1 VMOS power FET amplifier stage.
HEE HAW ELECTRONIC SIREN
The oscillator based on IC2 is responsible for producing the sound. Its output is connected to the base of TR1, which amplifies it to drive the speaker. Resistor R4 is included in the circuit to limit the current through TR1 to a safe and reasonable level. The oscillation frequency of IC2 is partially dependent on the values of R3 and C2. Another
For normal wailing tone, short D1 and open R2. For fast rise and slow fall in frequency, include D1 and R2. Use of a CD4046B with a diode-RC network as shown produces a siren tone, using a VCO.
SIREN GENERATOR CIRCUIT
An adaptable siren generator circuit with a multitude of uses is shown. It is based around a 556 twin-timer chip, IC1. An audio tone is created by one timer section and is directly coupled to the driver transistor, TR1. The other half of the timer is used to modulate the frequency of the audio tone using the CONTROL VOLTAGE pin terminal of the...
dub siren circuit
The aim of this project was to have a bespoke object made using local manufacturing. At the time I was in dire need of a Dub Siren. I found a circuit diagram, with the help of an electronics engineer (Stephan), we drew a schematic, to which he added some space invaders. We then convinced the Imperial college to print 4 circuit boards for me. I ass
A Battery Powered Burglar Alarm With A Timed Siren Cut-Off
This is a single zone alarm - with independently adjustable Exit, Entry and Siren Cut-Off timers. It will accommodate the usual types of normally-closed input devices - such as magnetic-reed contacts, foil tape and PIRs. If you wish - you can use a mains power supply. But the extremely low standby current makes battery power a realistic option. I`
Surveillance Bug Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
DIY HV Variable Capacitor
DIY PMA Alternator Plans
Digital Signal Integrity