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Over-speed Alarm

Has anyone tried building the ‘ Over- speed Alarm For Two Wheelers’ circuit published in May 2011 edition of EFY? I am facing some problems. The output of IC LM2917N at pin 10 is not coming as desired. The circuit is working only up to the output of LM358.

Bhuvan Raj EFY: If you are checking the output with a multimeter, it will not display proper voltage level at pin 10 of IC3. You will get only pulses which you can observe from an oscilloscope. Here are some tips to troubleshoot the problems:

1. Ensure proper power supply.

2. Adjust VR1 such that LED1 glows bright.

3. Feed 6 Hz at pin 2 of IC2. You can also generate 6Hz signal using 555 timer. As per relationship, 6 Hz equals 40 kmph.

4. Adjust VR2, VR3 and VR4 such that you hear sound from the speaker.

Hall sensor on the front wheel of the bike as described in the article.