Controlling 10 mA Relay with Opening/Closing Switches

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SUMMARY

The discussion centers on controlling a 10 mA relay using opening and closing switches. Participants agree that a proper circuit configuration, including a PNP transistor and a parallel power diode, is essential for effective operation. The relay coil, being an inductor, requires a diode to prevent damage from inductive reverse voltage spikes. Misdrawn circuit diagrams were identified as a common issue, emphasizing the need for accurate schematic representations.

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  • Understanding of PNP transistor operation
  • Knowledge of relay circuits and inductive loads
  • Familiarity with diode functions in electronic circuits
  • Basic circuit diagram interpretation skills
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  • Research proper circuit configurations for controlling relays with transistors
  • Learn about the role of diodes in protecting against inductive kickback
  • Explore common relay types and their specifications
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Electronics enthusiasts, hobbyists, and engineers interested in relay control circuits and transistor applications will benefit from this discussion.

John1397
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Can opening and closing switch turn on and off 10 ma relay
213876-37ca1887f27360392fe41e7e88c748a7.jpg
 

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John1397 said:
Can opening and closing switch turn on and off 10 ma relay
View attachment 230796
Not as drawn, but with a couple more resistors (or just a different configuration) and a diode, it can work. Have you tried using Google Images to find such circuits? Where did you get this one?
 
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berkeman said:
Where did you get this one?

I think it's just misdrawn. NPN is supposed to be a PNP. I personally wouldn't do it that way but with the correct PNP it should work...
 
eq1 said:
I think it's just misdrawn. NPN is supposed to be a PNP. I personally wouldn't do it that way but with the correct PNP it should work...
Ah, interesting thought! At least it will work once with the PNP (and no diode)... :wink:
 
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The relay coil is an inductor so it needs a parallel power diode to prevent the inductive reverse voltage spike that will otherwise destroy the transistor when the switch turns off and the magnetic field collapses.
 

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