Here is a circuit of simple, inexpensive and very useful project beeper and visual indicator, used to visual indicator lights up with each beep having the same time period.

Circuit description of beeper and visual indicator

This entire circuit of beeper and visual indicator is build and fabricated around two timer ICs and is configured in an astable multivibrator mode. The frequency generated by IC₁ is controlled by capacitor C₁. The output from pin 3 of IC₁ is given to input pin 4 of IC₂ and base of voltage amplifier transistor T₁ through resistor R₄. Flashing light is connected to collector of switching transistor T₂ and grounded through resistor R₇.

The output of IC₂ is obtained from pin 3 and is given to base of power amplifier transistor T₃ used to drive 8-ohm speaker connected to the collector.

NOTE: LED can be replaced with 3V to 12V DC bulb after eliminating resistor R₇.

PARTS LIST

Resistors (all ¼-watt, ± 5% Carbon)

R_1, R7 = 330 Ω

R₂ = 6.8 KΩ

R₃ = 5.6 KΩ

R₄ = 47 KΩ

R₅, R₆ = 22 KΩ

Capacitors

C₁ = 100 µF/10V electrolytic

C₂, C₄ = 0.1 µF ceramic disc

C₃ = 0.01 µF ceramic disc

C₅ = 1000 µF/25V electrolytic

Semiconductors

IC₁, IC₂ = NE555 (Timer IC)

T₁ = BC148B Replacements: BC141 , BC140, 2N2222

T₂ = = SK100 Replacements: BEL100 , 2N5401, BC177 If using replacement proper management for heat dissipation is advised.

T₃ = SL100B Replacements: 2N4922 , 2N4921,2N4238, FCX1053A

Miscellaneous

SW₁ = Push-To-On switch

LS₁ = 8-ohm loudspeaker

LED₁ = Flashing LED

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