Beeper & Buzzer

This box is a portable “transfer standard” to maintain and carry with you a ‘local’ time signal of 59 short beeps (pips) plus a long 0.4 sec beeeeep on the full minute. At the start of the job, the box is started by manually synchronising it “by ear” with a reputable time signal (GPS, WWV/H, or Telstra 1194 on a fixed landline telephone). The box then keeps bleeping, can be taken to an observation site, and can be used there for an hour or so, before the time slowly ‘drifts’ too far out of calibration.

Beeps 7.5 seconds after a preset time Adjustable time settings: 15 s. 30 s. 1 min. 2 min. & others This circuit is intended for alerting purposes after a certain time is elapsed. It is suitable for table games requiring a fixed time to answer a question, or to move a piece etc. In this view it is a modern substitute for the old sandglass. Useful also for time control when children are brushing teeth (at least two minutes!), or in the kitchen, and so on.

Beeps when hears your whistle A gadget suitable for key-holders, games etc. These devices contained a special purpose IC and therefore were not suited to home construction. The present circuit is designed around a general purpose hex-inverter CMos IC and, using miniature components and button clock-type batteries can be enclosed in a matchbox. It is primarily a gadget, but everyone will be able to find suitable applications.

The simple circuit in Figure 1 latches on an LED and an audio sounder when an appropriate new audible e-mail signal occurs. The method replaces the normal e-mail sound.wav file with a .wav file of any valid recorded dual-tone multifrequency (DTMF) sound. The circuit listens for the DTMF tone and latches on LED D1 and the piezoelectric buzzer, P1.

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 maximum efficiency.

For some medical equipment it is important for an operator when power is lost to the machine. The beeper is powered from a 9v battery and requires the machine to have a power switch with a third set of contacts.

Pushbutton Activated Service Request Beeper, A single press of a pushbutton switch turns on a beeper for one second but can’t be activated again for 60 seconds.

This circuit produces a short beep once each minute. It is powered directly off the 120vac power line to remind you that a device connected to the circuit is turned on. It is simple enough to be packaged inside a small plastic box. It might be ideal for computers, printers or some test equipment that shouldn't be left on all night.

Two different switch circuits are shown. One sources current and the second sinks current. Both switches are connected to a piezoelectric wafer. When the wafer is tapped, the switches are activated.

An inexpensive piezoelectric wafer is used to detect vibration and when the vibration is sufficient a switch is activated.

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.

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.

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

This circuit produces the sound of a beeper like the one in pagers which produces a "beep-beep" sound. Basically the circuit consists of a 555 timer oscillator which is turned ON and OFF periodically. The first IC(left) oscillates at about 1Hz. The second IC is turned ON and OFF by the first IC. The first IC determines how fast the second IC is turned ON/OFF and second IC determines the tone of the final output.

Three circuit options Can be synchronized to Christmas tree flashing lights This circuit generates a dual-tone bells ringing similar to most door-bell units. It can be used in many applications other than door-bell. In the Notes below several options will be given in order to suit different needs.

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.

The signal generation circuit is often built around standard 555 timers, although other systems may use discrete transistor circuits, op-amp derived circuits or even small microcontrollers. The 555 configuration will consist of a slow running astable multivibrator, generating a ramp signal, which modulates a second multivibrator causing it to sweep over a range of frequencies.

An AC millivoltmeter - calibrated in dB - with a range of 30V down to 3mV full scale (80dB range) would be extremely useful. Attach a microphone (electret mic capsules are quite good), and you have a relative sound level meter, even better if you have some way of calibration. The meter presented here has a very wide frequency range, and uses a switched attenuator for range adjustment. The attenuator uses the 30-10-3 sequence, which provides 10dB steps between ranges. The standard attenuator provides an input impedance of over 2M Ohms,

This circuit provides an audible and visual low voltage warning for 12V battery powered devices. When the battery voltage is above the set point (typically 11V), the circuit is idle. If the battery voltage should fall below the set point, the LED will light and the speaker will emit a periodic beeping sound to warn of the impending loss of power. The circuit was designed for monitoring solar systems, but it could also be useful for automotive and other 12V applications.

BASEMENT BEEPER TURNS ON WHEN DOOR CHIME IS ACTIVATED