|
3v Powered Loud Beeper - Getting a high sound intensity from a piezoelectric type beeper is not easy when the available DC supply is only 3v. The circuit below is not only efficient but produces a very intense sound. The circuit combines a voltage boost section with a resonant. . . Circuit by David A. Johnson P.E.-February, 2009
3v Sweeping Siren Alarm - A while back I was challenged by a visitor to the website. He needed a very loud sweeping siren type audio sound generator powered by 3v. He tried some of the commercial sirens but they were not very loud when powered by 3v. He also said that those. . . Circuit by David Johnson P.E.-June, 2008
555 Siren Generator - a simple design from 2 555 timersthis is versatile and loud. __ Contact: P. Townshend EduTek Ltd
555 Tone Generator 8 Ohm Speaker - This is a basic 555 squarewave oscillator used to produce a 1 Khz tone from an 8 ohm speaker. In the circuit on the left, the speaker is isolated from the oscillator by the NPN medium power transistor which also provides more current than can be obtained directly from the 555 (limit = 200 mA). A small capacitor is used at the transistor __ Designed by Bill Bowden
A Simple Circuit electronic buzzer - This very simple circuit just uses a couple of resistors, a capacitor and the easily available 555 timer IC. The 555 is setup as an astable multivibrator operating at a frequency of about 1kHz that produces a shrill noise when switched on. The frequency can be changed by varying the 10K resistor __ Designed by Radioland.nt.au
AC Power Loss Alarm - I’ve been having a problem with my instant hot water system lately. This system circulates electrically heated water throughout my house using a small pump. The pump is wired into a ground fault interrupter (GFI) module. Every now and then, the GFI trips, leaving me without hot water. . . Circuit by David Johnson P.E.-March, 2009
Add a door-chime repeater - 05/13/99 EDN-Design Ideas Electromechanical door chimes can enhance your home, but they are vulnerable to costly repair problems. A defective pushbutton switch or a careless visitor can maintain the chime in an energized state for a prolonged period, thereby damaging the chime. The circuit in Figure 1 prevents damage to the chime and improves the chime's effectiveness by repeating the chime strike for as long as the pushbutton remains depressed. The circuit controls both front and rear chimes. The heart of the circuit is timer IC2, which you configure as an astable multivibrator. The timing components, R1, R2, R3, and C3, provide the required pulse widths. Design by Dennis Eichenberg, Parma Heights, OH
Alarm Beeps when the “Check Engine” Light Turns On - When wired into a car’s indicator light panel, this circuit will turn on a loud beeper when the “check engine” light turns on. . . Circuit by David A. Johnson P.E.-July, 2006
Ambulance Siren - This siren circuit simulates police, fire or other emergency sirens that produce an up and down wail. __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Another Game Show Timer - Several Game Show timers included, scroll to find this one. Here is a somewhat more complex version that uses easily found bipolar transistors. Note that it requires only two wires between stations and base and those wires can be connected anywhere on the "buss". (You can wire each station back to the base unit or "daisy chain" the stations from one to the next with only one set of wires going back to the base unit.) __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Another Very Loud piezo Alarm Beeper - This is yet another beeper circuit that really draws attention. It sweeps the drive frequency slightly to produce a very annoying sound. It uses a transformer to increase the drive voltage across the piezo device to more than 200 volts peak to peak. . . Circuit by Dave Johnson P.E.-June, 2000
Appliance Unplugged Alarm - I received a call from an administrator at a large prison. He told me that he was having problems with inmates who keep unplugging refrigerators, vending machines and microwave ovens in a commons area. He wanted a battery-powered device, which could be mounted to the outside of the power cord of an appliance. . . . Hobby Circuit designed by David A. Johnson P.E.-April, 2010
Audio MilliVoltmeter - For Testing Amplifiers (etc) , An analogue design, 3mV to 30V with dB scale __ Designed by Rod Elliott ESP
Automatic Heat Detector - This circuit uses a complementary pair comprising npn metallic transistor T1 (BC109) and pnp germanium transistor T2 (AC188) to detect heat (due to outbreak of fire, etc) in the vicinity and __ Electronics Projects for You
Basement Doorbell Beeper - If you can't hear your doorbell when you are in your basement try this circuit. This circuit takes advantage of the 24vac power source located near the furnace. Using a simple current transformer technique, the circuit sounds a beeper whenever the. . . Circuit by Dave Johnson P.E.-June, 2000
Basement Remote Doorbell - This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac . . . Hobby Circuit designed by David Johnson P.E.-July, 2006
Battery Low Voltage Beeper - This circuit provides an audible and visual low voltage warning for 12V battery powered devices. Idle current: 6ma Low Voltage Warning current: 15ma. __ Designed by G. Forrest Cook
Beeper Bug - This bug can be attached to anything from a glider to a plant and you can track it with a radio. Why track a plant? The Beeper is the result of many requests for a mini tracking device and introduces a new world of tracking __ Contact: Collin Mitchell
Beeper indicates Check Engine - When driving down a busy road, you may not notice a “check engine” indicator light that suddenly turns on within the car’s instrument panel. You could drive for many miles before noticing the light. To provide an audible indication of trouble, the hobby . . . Hobby Circuit designed by David Johnson P.E.-July, 2006
Beeper that is Very Loud - This circuit generates a continuous tone instead of a pulsing one. The circuit delivers about 110db (12 inches away) from a 9v battery using a single inexpensive C-MOS IC. An off-the-shelf piezoelectric beeping device is driven at resonance to insure maxim. . . Circuit by David Johnson P.E.-June, 2000
Bell-Cum-Light Controller - This bell-cum-light controller circuit is equipped with four switches labelled S1 through S4. While S4 is the mains ‘on’/‘off’ toggle switch for powering the timer circuit for lighting up a bulb __ Electronics Projects for You
Bells ring Generator - Three circuit options; Can be synchronized to Christmas tree flashing lights __ Contact: Flavio Dellepiane, fladello @ tin.it
Birdie Doorbell Ringer - P1 is of experimental value. Start with 220 Ohms or so and modify to suit your needs. The transistor is a general purpose kind and is not critical, almost any PNP type will work. L1 is a bell-transformer which is usually already present in the house. If you wish, you could use a battery instead of the bell transformer. Just hookup a 9-volt battery (or wall adapter) to points 'A' and 'B' (A=+) the diode (D1) is to protect the circuit from accidental polarity reversal and is optional, but required as a rectifier for use with the bell transformer __ Designed by Tony van Roon VA3AVR
Blown-Fuse Indicator Sounds an Alarm - 10-Jul-08 EDN-Design Ideas A simple blown-fuse-indicator circuit sounds a buzzer and flashes an LED when a fuse blows Design by Vladimir Oleynik, Moscow, Russia
Buzzer for use as a doorbell - How often on average do you have to call members of your family each day to tell them that dinner is ready, it’s time to leave, and the like? The person you want is usually in a different room, such as the hobby room or bedroom. A powerful buzzer in the room, combined with a pushbutton at the bottom of the stairs or in the kitchen, could be very handy in such situations __ Learning Electronics
|
