Door Bell Circuit

circuit diagram of door bell

This project describes the constructional and working details of a door bell circuit. The door bell circuit presented here is of 2-notes (modulated sound) type and delivers about 4-watt Musial power at 12 volt. While using it as a door bell circuit, 6V DC supply is enough, which can be derived either from dry battery cells or a battery eliminator. The door bell circuit is flexible enough to work off right from 6V to 18V supply, without change of any component in the circuitry. However, it is important to use…

Read More

Toy Siren Circuit Using CD7400

circuit diagram of toy siren using cd4700

Various sound generating project is posted in Alarm and Sound Generation Section. Now here is very simple an easy to construct electronic project called Toy Siren using CD7400 (IC1). Circuit Description of Toy Siren Circuit Using CD7400 The heart of the project toy siren circuit is quad-2-input NAND gate IC CD7400 (IC1). IC1 (CD7400) is a cheap easily available IC and it consist four NAND gate. Two NAND gate out of four is configured as low frequency oscillator and another two NAND gate as high frequency oscillator. When output of…

Read More

Beeper Circuit using Timer IC 555

circuit diagram of beeper using timer ic 555

Here is a beeper circuit employing two timer ICs NE555 (IC1 and IC2). The beeper circuit using timer IC NE555 can be used in various circuits that require an alarm or a ‘beeping’ signal. Description of Beeper Circuit Using Timer IC NE555 Timer IC1 is  used here  in astable mode in such a way that square-wave output at about 1 Hz is obtained. IC2 is also configure  in astable mode, but it gives an output with about 1 kHz frequency. The output if IC1 (pin 3) is connected to ‘Reset’…

Read More

Multi Tone Generator Circuit

multi tone generator circuit

Here one another sound generator project is added is section of alarm and sound generator projects. We have tested and posted dozens of sound or tone generator projects. Now, here is multi-tone generator circuit which produces eight different types of tones. The tones produced by the circuit multi tone generator are of Bell, Ambulance Siren, Whistle, Machine gun Sound, Jingle, Police siren, Birds and Dual sound. Circuit Description of Multi Tone Generator Circuit The heart of the circuit multi tone generator is UM5561 IC (IC1) and the entire circuit is…

Read More

Low Power Alarm with Automatic Timer

low power alarm with automatic timer circuit

Various types of alarm and sound generator circuit is already published in bestengineeringprojects.com. Now here is a alarm circuit which draws very low quiescent current and also does not need any type of power on off switch because this offers automatic switch-off after fixed time. Circuit Description of Low Power Alarm with Automatic Timer The heart of the circuit low power alarm circuit is 4060 IC, which is here configured as timer. The advantage of using IC 4060 (IC1) is the wide music range instead of UM series musical IC.…

Read More

Charging Reminder for Emergency Light

charging reminder for emergency light

When the battery is kept in the discharge state for a long period, irreversible chemical reaction takes place reducing the capacity of the battery so that eventually the battery becomes useless. No protection circuit can stop self discharge of the battery and only trickle charging on compensate for it. Here is a circuit charging reminder for emergency light to inform the user that the battery has discharged itself below the safe level. The discharge characteristics of a dry battery, as supplied by its manufacturer indicate that the battery should not…

Read More

Miniature IC Organ Circuit

miniature ic organ circuit

Here is a circuit for an miniature IC organ using 3-volt AF amplifier IC TDA2822. Frequency of the AF sound generated depends on the capacitor between pin 1 and pin 7 of IC. When switch SW1 to SW10 are pressed, different audio tones are heard from the speaker. SW1 to SW10 are small push-to-on switches. Pin 2 of IC is connected to positive terminal of 3-volt battery. Two pen cells connected in series can be used to power this circuit. Satisfactory loud sound will obtained at 3-volt supply. Note: Capacitors…

Read More

Light and Touch Operated Music Door Bell

light and touch operated music bell

The novel circuit light and touch operated music bell used a photo transistor (T1) with an npn transistor in emitter-follower mode to increase sensitivity of the circuit. So even if very little light fall on the photo transistor, it gives a triggering pulse to SCR gate and the SCR starts conducting. Circuit Description of Light and Touch Operated Music Bell When SCR conducts, IC UM66 starts producing music. After the music has halted, no current flows through the SCR and the SCR switches off till the light falls again on…

Read More

12 Tones Doorbell

12 tone doorbell circuit

Every day addiction of people towards technology is growing deeper and deeper, even before entering into someone’s house we press doorbell which is a clear example to support our belief. Listening same doorbell always might be boring, this circuit 12 tones doorbell help us to avoid this dull situation. Music doorbells, music horns, touch-sensitive doorbells, etc are not new projects electronics hobbyists, especially for BEP readers. But, this music producer (twelve popular tones in sequences) gives a new dimension to musical doorbells. Whenever a switch is pressed, a popular tone…

Read More

Electronic Siren Circuit using OP-Amp 741

Electronics siren circuit

Here is an inexpensive electronic siren circuit built around the most popular and low-cost IC 741. The circuit is basically a square wave generator that is used here to produce the tone of a siren. Circuit Description of Electronic Siren Circuit using OP-Amp 741 The IC1 is used as a low-frequency multivibrator, the output of which modulates the high-frequency tone produced by the IC2 multivibrator. The final output is amplified and converted into a loud siren by transistor T1 and the speaker. Various interesting tones can be obtained by changing the…

Read More