Mixed circuit "Timer"

Mixed circuit project "Timer"

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Timer based on capacitors charging time, with a transistor logic.

Scheme

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  • C1, C2 - "charging elements", more capacitors will increase the time.
  • Q1 with role a logical "not", when capacitors charged, then voltage equal to 0, but with this transistor - voltage exist.
  • R2 placed for tests, in the experiment it is LED, visualizing the process.

Plot

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  1. [0, 4] seconds: slowly growing, this time possible to increase by adding more capacitors
  2. [4, end] seconds: regular grow of capacitor, but inverted by "not" transistor
  3. [11, end] seconds: enough voltage for LED, in this period of time the LED must emmit

Experiment

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Tested on a breadboard. ~14,15 second is starting to emit, -1,2 sec for connection.

Result

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How to make better

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LED is starting slowly, like a curve, but for time important the straight point.

Read more:

Schmitt trigger

References

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https://www.dummies.com/article/technology/electronics/circuitry/electronics-projects-how-to-create-a-transistor-not-gate-circuit-179357/