Thread: Sinusoidal Phase Shift

Originally Posted by meastwood98

Hi,

I am trying to phase shift a sinusoidal signal by a small amount (a degree or two), I am aware I could do this with some ADC and microprocessor. However I would like to do it with some simpler analogue electronics, I have been looking at an "all-pass filter", however my signal will have a varying frequency and therfore this will not work as an "all-pass filter" will only work for a certain frequency. Any ideas?

Any help would be much appriciated?

Thanks,
Mark

hi Mark,
What are the frequency limits, min/max and how 'accurate'.??

hi,
This very simple circuit accepts a 0.5Vpk sinewave signal and shifts it a few degrees.

Over the range of 100Hz thru 1KHz the phase shift does vary a little.

Do you use the LTspice simulator.?

Originally Posted by meastwood98

No, i use NI multisim to simulate circuits. Would it be possible to modify the circuit to run it from a 5v supply?

It should be OK at +5V, the output swing will be reduced.

Give it a try,,, the value of the 820R changes the amount of shift, try a few different values.

Lets know how it goes.

Originally Posted by meastwood98

Sorry, I fogot to mention my signal is a sinusoid that has an offset, its magnitude is 1.2v pk-pk and is offset 2.5v. That circuit works fine for a signal with no offset, can it be modified to work with my signal?

Thanks,
Mark

hi Mark,
Is that a 'dc' offset of 2.5V.? , ie: its a 1.2Vppk superimposed on +2.5Vdc level.?

Can you post your Sim circuit.?

Originally Posted by meastwood98

Yes so the peak value is 3.1v and the trough is 1.9v, I dont have a sim circuit, I just built up your circuit to test it.

hi,
OK, I'll re-look at it.

hi Mark,
Just sims OK.
The images are for 1KHz, 500Hz and 100Hz[ with the cct].

The 2nd stage is bring the output to the same level as the input, if required.

Note the fairly high output impedance.

Originally Posted by meastwood98

From my simulation of the circuit the phase shift is dependant on frequency, are you sure you didnt adjust the value of R when testing it at different frequencies?

No I didnt.

Originally Posted by meastwood98

Ok. Any ideas to where im going wrong?

hi,
I have just re-run the sim, this time using a sweep freq, same results as the ones I posted.

Please post the simulation details and circuit that you are using, also with some details of the changes being observed.