We can check any mechanical watch by hear tick – tick sound whether it is working or not but to check any electronics quartz watch which does not have second needle is quite tedious work because no sound is produce. To check this type of watch a circuit “Quartz Watch Tester” is used.

Circuit Description

The circuit of quartz watch tester utilize a amplifier IC a coil of few turn and a transistor. The pulse produced by watch is pick–up by coil of 30 – 50 turns made from 42 SWG copper wire over 45mm * 4 mm iron nail. The pulse from coli is given to base of transistor T₁ through capacitor C₉. Transistor T₁ is used as pre – amplifier. The output of pre – amplifier i.e. from collector of transistor T₁ is given to input pin 8 of IC₁ through capacitor C₇. IC₁ (TBA810) is a audio amplifier IC which further amplify the pulse up to desired level and fed to loudspeaker through capacitor C₆ for output.

PARTS LIST

Resistors (all ¼-watt, ± 5% Carbon)

R₁, R₂ = 100 Ω

R₃ = 100 KΩ

R₄ = 2.2 KΩ

R₅ = 390 KΩ

R₆ = 470 KΩ

Capacitors

C₁ = 220 µF/10V

C₂ = 0.001 µF

C₃ = 0.005 µF

C₄, C₅, C₇ = 100 µF/16V

C₆, C₁₀ = 1000 µF/16V

C₈ = 33 µF/16V

C₉ = 1 µF/50V

Semiconductors

IC₁ = TBA810 (audio amplifier)

T₁ = BC147

Miscellaneous

SW₁ = ON/Off switch

LS₁ = 8 Ω loudspeaker

L₁ = 30 – 50 turns of 42 swg copper wire over 45mm*4mm iron nail