# How to build a delay circuit?

Discussion in 'General Electronics Chat' started by dbroadberry, Oct 25, 2010.

Oct 25, 2010
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I'm a final year physics student and as part of my final year project I need a circuit that can provide me with two sine waves ∏/2 out of phase with equal maximum/minimum.

I will be using a signal generator to provide me with a steady sine wave input with constant magnitude but varying frequency.

My knowledge of electronics is very basic but I imagine I need something like a two branch circuit that has a capacitor in one branch and another branch that allows the input signal to pass through unchanged.

Basically I need two output signals ∏/2 out of phase from a single input signal.

Can anybody help?

Dan

2. ### Ron H AAC Fanatic!

Apr 14, 2005
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It is very difficult to do with purely analog circuits, unless you generate the signals with a quadrature oscillator instead of a signal generator with a single output.

3. ### atferrari AAC Fanatic!

Jan 6, 2004
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Last edited: Oct 26, 2010

Oct 25, 2010
2
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Thanks for the replies. I'm not 100% certain of my frequency range yet as it will depend on the physical geometry of the system for which the circuit is going to be used to control (a linear synchronous motor) but I imagine it will be between 0 and 100Hz.

That document seems to be quite detailed but also suggest that I'm going to have issues with the output voltages as I vary the frequency of the input. I really need to have a constant voltage across all the frequencies I use.

It occurred to me earlier that I may be over complicating the situation. As the 1st derivative of sine is cosine, is that a circuit that essentially take the derivative of an input signal?

5. ### Ron H AAC Fanatic!

Apr 14, 2005
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The derivative of sine(ωt) is ωcos(ωt), i.e., the amplitude rises linearly as a function of frequency.

Apr 14, 2005
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7. ### Ron H AAC Fanatic!

Apr 14, 2005
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As Agustin suggested, the best solution is probably DDS (direct digital synthesis), but it is not simple for a novice.

8. ### atferrari AAC Fanatic!

Jan 6, 2004
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Yes, it seems that THAT could be a problem.