555 timer

303

05:10:53

So I was looking at this simple 555 timer circuit in a book called "The Art of Electronics" and I converted the output to a sin wave with a LC oscillator and well this happened. Can someone explain why this happened? I am aware this simulator has limits but its just funny. XD

published 5 years ago

BillyT

5 years ago

The 555 likes some type of resistive output to ground, if you put any square wave source thru an LC filter to ground you will get a similar result.

Robert_Kidd

5 years ago

As BillyT says, it’s been shown that you need (at least) a 15 Ohm resistor in series with the output pin. Note that EC inductors are ‘perfect’ in that they possess no resistance. Add in a bit of resistance and note how output changes.

pieshower

5 years ago

AHA that fixed it well. Thank you! I see since there was no resistance the Voltage kept swinging up each oscillation until the simulation couldn't keep up.

Robert_Kidd

5 years ago

Pleasure :-)

Beaker651

5 years ago

The values of L and C are wrong, does not match frequency of your square wave, not in resonance. Second simulators suck. Use breadboard not this simulator. don’t need resistor at the pin. The output is located between the inductor and capacitor.

Robert_Kidd

5 years ago

Which resistor at which pin?

Robert_Kidd

5 years ago

Do you know?

pieshower

5 years ago

I guess I could of calculated it but I just kept changing the resonant frequency of the tank until it gave me a smooth sinusoidal output.

pieshower

5 years ago

And I would use a breadboard but I currently do not own a 555 timer. Was just looking at different types of oscillator circuits. I’m still fairly new to electrical engineering but it is what I am going to school for. And I enjoy this very much.

pieshower

5 years ago

There I adjusted the output frequency. I just noticed that the scope showed the estimated frequency of the square wave. It’s just fun to change the inductance and capacitance of the tank and see how it affects the output signal.

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