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Annunciator - Beeper & Buzzer Schematics

24V DC Powered Beeper with 4 Separate Inputs - 24v DC is a very popular voltage used in industrial settings.  The circuit below was designed to accept four different 24v DC alarm input signals, which are then used to drive a single low power beeper.  The beeper is a magnetic type with its own oscillator/driver.  The four diodes form an “OR” gate so any one of the four inputs will cause the beeper to make noise.  A CMOS version of the popular 555 timer is used to strobe the beeper on and off at about 1Hz..

3V Sweeping Siren Alarm - The circuit uses a LTC1799 precision frequency generator from Linear Technology.  A 74HC14 hex Schmitt trigger from Texas Instruments is also used to perform several other functions.  One section is wired as a simple 7Hz square wave oscillator.…

555 Tone Generator 8 Ohm Speaker - This is a basic 555 square wave 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....

American Police Car Siren (linscott) - Scroll down to locate this circuit. The 555 on the right is wired as an alarm tone generator and the second 555 timer on the left is wired as a low frequency astable timer which generates a ramp waveform of about 6 seconds that is buffered by the transistor and again used to frequency modulate the tone generator. The transistor is used to help strengthen the signal to the speaker..

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 piezoelectric device to more than 200 volts peak to peak. It cranks out an ear splitting 120db when measured at 12 inches.

Assortment of Siren Circuits

Audio MilliVoltmeter - For Testing Amplifiers (etc), An analogue design, 3mV to 30V with dB scale

Automotive & Household Siren Driver Circuits: Zsd100 & Discrete 'H'-Bridge Minimum Parts Count Solution - Zetec Semiconductors  Applications Notes A solution is provided that uses a minimum number of components by utilizing an application specific signal generation IC, and a high efficiency 'H'-bridge effected with 3A DC rated Super-δ TO92 style switching transistors.

Basement Doorbell - This circuit will activate a beeper in the basement, whenever the front doorbell is pressed.

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 main door chime is activated.

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…

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…

Bells Ring Generator - Three circuit options.  Can be synchronized to Christmas tree flashing lights.

Birdie Doorbell Ringer

British Police Car Siren - The first circuit simulates the siren of a British police car. It uses two 555 timers in the circuit. The 555 on the right is wired as an alarm tone generator and the second 555 timer on the left is a 1 Hz astable multivibrater...


Check Engine Beeper - When wired into a car’s indicator light panel, this circuit will turn on a loud beeper when the “check engine” light turns on.

Click Sound Generator - Often in computer controlled systems, you would like to generate a “click” sound whenever a button is pressed.  This provides the user with audible feedback that the pushbutton press has been acknowledged.  The two circuits below generate such a sound.  A click sound is generated each time the logic input swings from a logic low to high condition.....

Continuity Buzzer is Frugal with Power - EDN-Design Ideas: [Note: File contains multiple circuits.  Scroll to find this one]  The continuity detector in Figure 1 is based on W Dijkstra's "Fleapower circuit detects short circuits" (EDN, July 2, 98, pg 122). The buzzer indicator allows you to devote full attention to making the connection without having to observe an LED. The circuit also consumes less....

Controller Provides Multiple Alarm Driver Formats - EDN-Design Ideas: DC/DC converters for use inside the telephone handset require operation from the high-source-impedance phone line. Additionally, the CCITT specifications call for maximum on-hook power consumption of 25 mA. The dc/dc converter in Figure 1 is 70%-efficient at an input power of 25 mA, providing 5V at 3.4 mA. Controlled, low-peak switch current ensures that the ­48V input line experiences no excessive voltage drops during switching...

Counter with Doorbell

Cuckoo sound Generator - This circuit generates a two-tone effect very much alike the cuckoo sound. It can be used for door-bells or other purposes thanks to a built-in audio amplifier and loudspeaker.  Used as a sound effect generator it can be connected to external amplifiers, tape recorders etc. In this case, the built-in audio amplifier and loudspeaker may be omitted and the output taken from C8 and ground.

Curious C Beeper - The Curious C-Beeper uses the two-transistor flasher in conjunction with a darlington transistor to make a most unusual capacitance beeper probe. When a capacitor is touched to the probe, the probe beeps at a frequency that varies with capacitance.

Destroyer Whooper Alarm - If you've ever watched any TV at all and seen those old WWII navy movies, you've heard that distinctive "whoop-whoop-whoop" as a destroyer sliced through the waves, guns blazing, and everybody yelling "battle stations!"

DIN Audio Pinouts -

Ding-Dong Bell

Door chime Privacy Sentry ATtiny12  - An ATtiny12 controller as a timer and some switching circuitry turns the doorbell off for 10 hours at the same time each day…

Door Knock Beeper - In some apartment buildings and homes, not equipped with a door bell, it may be hard to hear someone knocking on the front door.  The circuit below provides a means to activate a loud beeping sound inside, whenever someone knocks on the door from the outside.  The circuit is powered by a 9v battery, which should provide years of service.  An on/off switch allows the device to be turned off if desired..

Doorbell Chime

Doorbell for the Deaf (Andy Collinson) - This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words "Please Wait" for anyone with walking difficulties..

Doorbell Indicator-Remote

Doorbell with Counter
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