How can a square wave generator be used in a resonance inductive circuit?

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Discussion Overview

The discussion revolves around the use of a square wave generator, specifically one built with a 555 timer, in resonance inductive circuits or inductive coupling applications. Participants explore how to integrate the generator into such circuits and address various technical aspects related to its operation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant describes their construction of a square wave generator using a 555 timer and seeks guidance on its application in a resonance inductive circuit.
  • Another participant suggests that the output can be taken from the negative terminal of the supply and the output pin (pin 3) of the 555 timer, and questions the definition of "resonance inductive circuit."
  • It is proposed that if the circuit is a series tuned circuit, the 555 timer can drive it directly, although concerns are raised about the low frequency outputs of the 555 timer and the size of inductors required for such frequencies.
  • A participant mentions that the 555 timer can be operated at higher frequencies (up to 500 KHz) with appropriate component values.
  • Clarification is provided regarding the output pin of the 555 timer, with a participant asserting that it is always pin 3.
  • Another participant suggests a circuit configuration involving a power transistor and a step-up transformer, indicating that the primary of the transformer should replace a lamp in the proposed circuit.
  • Concerns are raised about the absence of a power supply in a referenced image, indicating confusion about the circuit setup.
  • A participant notes that the 555 timer does not produce a true 50% duty cycle square wave, which may affect precision measurements, and recommends using a divide by 2 flip flop for better accuracy.
  • It is advised that when driving an inductor, high voltage spikes may occur when the transistor turns off, suggesting the use of a damping diode in parallel with the inductor.

Areas of Agreement / Disagreement

Participants express differing views on the specifics of using the 555 timer in inductive circuits, including its output characteristics and the necessity of additional components for accurate operation. The discussion remains unresolved regarding the optimal configuration and the implications of the 555 timer's output.

Contextual Notes

Participants mention limitations related to the frequency capabilities of the 555 timer and the potential need for additional components to achieve desired circuit behavior, but these aspects remain unresolved.

alpine2beach
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Square wave generator...what?

Okay, so I built a square wave generator using a 555 timer and schematics that I found off the internet. Upon completion, I dumbly realized that there is only an output. I wanted to use the square wave generator in resonance inductive circuit, but seeing as there is only an output, how would I be able to work it into the circuit? If not, how would it be used?
 
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You can take the output between the negative terminal of the supply and the "output" pin (pin 3) of the 555.

Could you explain what your mean by "resonance inductive circuit" ?

If you mean a series tuned circuit, then the 555 can drive such a circuit directly, although 555s normally generate quite low frequencies and tuned circuits for such frequencies would have large expensive inductors in them.

By using small value components in the timing for the 555, they can be operated up to 500 KHz or so. Maybe higher.
 


vk6kro said:
You can take the output between the negative terminal of the supply and the "output" pin (pin 3) of the 555.

Could you explain what your mean by "resonance inductive circuit" ?

If you mean a series tuned circuit, then the 555 can drive such a circuit directly, although 555s normally generate quite low frequencies and tuned circuits for such frequencies would have large expensive inductors in them.

By using small value components in the timing for the 555, they can be operated up to 500 KHz or so. Maybe higher.

Thank You! I know I didn't really word "resonance inductive circuit" correctly; I meant inductive coupling. I want to be able to create an inverting current using a 555 timer and dc current (such as a battery) to power an electromagnetic induction coil. And isn't the output pin pin#6? I guess it might depend on the manufacturer...
 


No, the output is always pin 3.

You probably need a circuit like this:

images?q=tbn:ANd9GcR97gDGJhcG4q3Y0sGJD40emIYouLU5DqvEGkqW5JXcy8CSb7JWIw.png


This shows a lamp in the collector circuit of a power transistor, but you would need the primary of a step-up transformer to be there instead.

This one is possibly more like what you would need:

images?q=tbn:ANd9GcRsmQlTqw9nt4OUYhcIiMqPGl_xfCSsxtejObVfUZ3_c9iHfEWbVQ.png
 


I think I must be misreading something... but where is the power supply (in image 1)?
 
Last edited:


The 555 will not give you a true 50% duty cycle square wave, which you need to do precision electrical measurements. The 555 output should be put through a good divide by 2 flip flop.

Bob S
 


Quick note: If you drive an inductor as shown in the first pic above, there'll be high voltage spikes just as the transistor turns off. So you might consider a damping diode (a diode in parallel with the inductor and pointing upward, in the circuit shown)
 

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