Op Amp Schmitt trigger

The Op Amp comparators sometimes works well under some conditions but not always. If there is a slow wave form or some noise on it, sometimes the output switch back and forth many times. So for stable operation, Op Amp comparator can be designed as a Schmitt trigger.
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Power status LED

Two LEDs indicate the power on and off status of bread board power . So it helps to confirm whether the positive and negative rails of the bread board are getting power. Green LED lights at power on and turns off after 3 seconds. Red LED turns on at power off and turns off after 3 seconds. Let us see the circuit

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It is easy to light an LED by directly connected to 220 volt AC. It can be indicator in AC devices or Bed lamp if White LED is used. If used as a Bed lamp, the circuit can be enclosed in a plug  with LED projecting out. Caution : The circuit is directly connected to high voltage that can give a fatal shock if handled … Continue reading LED in AC