Simple Phase Shifter

[@cooliocrib4409]

I used this circuit to set a tunable phase shift between 2 sinewaves at variablefrequency. I used 2 of these circuits one set +90 deg and the other set -90 deg. I now have a tunable phase shift via variable R and the phase shift is fixed across variable frequency 500KHz to 2.5MHz. Thank you much appreciate your video

[@thetuberoaster8321]

Awesome! Good to see that it's useful.

[@moses5407]

How did you combine the circuits and can you explain a bit more how this becomes frequency independent? Pardon my ignorance.

[@Richard-nt7dp]

Looks nice, what is the voltage amplitudes of the input and output signals? Peak to peak

[@thetuberoaster8321]

The input and output are approximately equal and are something like 550mV peak-to-peak in this video. It doesn't really matter though, as long as your peak-to-peak signal is within ~4.7V, it shouldn't clip.

[@magiclay]

hi...works with any kind of waveform?

[@thetuberoaster8321]

Yes, it should

[@magiclay]

​​@@thetuberoaster8321Great.... also...works at any frequency from 0-20khz?

[@pferamaya]

Hi, amazing video. Is it possible to make it work with a frequency of 80MHz? It's VHF and I dont really know how to do it, or how to do the calculations to get the values of the potentiometre and capacitor. Thx

[@thetuberoaster8321]

It is possible, but there's a chance it may not work in this configuration. You can try with an RF transistor in this circuit soldered onto a one of those copper-clad prototype boards. My guess is the stray capacitances of the transistor and components will not allow you to get a full 0 to 180 degree shift. In other words, it will work, but to what degree I'm not sure. I would suggest a cascode configuration but Miller capacitance is not really a factor here since the gain is unity. On the other hand, it may work but the amplitude of the signal coming from the collector might be dropped due to capacitive loading. You could try to to buffer it with an emitter follower. The output capacitor would need to be very small in order to get a large phase shift. For a phase shift of 175 degrees at 80MHz, you'll need a 46pF cap going into a 1k ohm pot. If the pot is a higher value, the capacitance will need to be lower. If the stray capacitance of the pot or capacitance of the emitter to collector/output is too great, the near 180 degree phase shift won't be realized. I recommend running the circuit at a higher current, thereby lowering impedances and decreasing the negative effects of stray capacitance. Run the transistor with 470 ohm load resistors and bias accordingly with 15k and 6.8k bias resistors. Go even lower if the transistor can handle it. This way, it can more effectively drive the stray capacitances and the lower load resistance (the potentiometer).

[@Terrar-fr1bk]

What's the frequency of the sine waves? Also, what transistor did you use? I don't think you mentioned that. I plan to adapt the circuit to RF and quite like the idea. The way I see it, it's essentially a phase splitter (transistor part), where you then have adjustable RC filter for the signal recombination. I think at higher frequencies the values for R and C are going to become a problem. Perhaps less if you use PCB and SMD components. Still, most standard inductors and capacitors have quite low Self Resonant Frequencies (~10MHz) so above that you need the more expensive RF components. Perhaps there is an alternative to using the RC filter.

[@gummybear-n7n]

how do u set the values of each components?

[@GenePurses]

what happens if you lower one of the 4.7 resistors? Will it result in some amplification if you lower the resistor closer to the input?

[@thetuberoaster8321]

If you make the emitter resistor lower than 4.7k, it will amplify the signal, but it will also phase shift it more since. The signal from the emitter will be lower than that of the collector, therefore it will act upon it less. As you change the 50k pot, the signal will change phase but also amplitude, arguably making it less useful.

[@kalakxfif9473]

how do i determaine the required R and C values for a given operating frequency?

[@thetuberoaster8321]

I replied to another comment similar to this which you can also look at. You can solve for RC in the equation but the trick is making the phase shift range large enough but useful. A 180 degree phase shift is not practically possible because it can only occur when the term for arc tangent is infinity. The best you can do is something like 176 or 178 degrees. If you solve for a phase shift much higher than 176, the range of the pot becomes really nonlinear and it does not sweep the phase range in a way that is useful. I'd recommend plugging in 176 degrees for the phase shift and the desired frequency to then solve for RC. This will correspond to the max value of the potentiometer. The 0 degrees phase shift condition is of course simple. When the pot is turned down it will go to 0 ohms or near enough making the phase shift nearly 0 degrees.

[@m.shehryar5341]

hi. how would I make this circuit for a frequency of 50 Hz?

[@thetuberoaster8321]

Studying the equation in the video, 180 degree phase shift can only occur when the term for arc tangent is infinity. This is not possible so we try to get close. In the video, I used a frequency of 1kHz, a capacitor of 0.1uF and a resistor of 50K (at max setting). This gave a maximum phase shift of 176 degrees which is close enough to 180. The idea is to make the change of the potentiometer usable; which means that the phase shifts fairly evenly over the whole turn. To make this work better at 50Hz, we can either increase the potentiometer to 220K, or increase the capacitor to 2.2uF. This will put the max phase shift at around 176 degrees. You may want to increase the 0.1uF input capacitor or you will may have a couple dB of attenuation.

[@m.shehryar5341]

@@thetuberoaster8321 thanks for the help. really appreciate it. keep making good videos like this!

[@kyleweaver7478]

Does this design still work in the HF range? I am having trouble getting it to simulate correctly.

[@thetuberoaster8321]

It should work depending on the transistor and layout. The real problem will be that the required capacitance might become so small (ones of pF) that interelectrode and wiring capactances might interfere. To circumvent this you can drop all the resistor values to give higher currents everywhere thus warranting larger (and more usable) capacitors for a given frequency. Capacitance of the potentiometer and inductance of wires might prevent you from being able to go 0 degrees all the way to 180, but I don't think this will be an issue until VHF or higher. Probably the absolute worst case scenario is it could oscillate near zero degrees phase shift.

[@tomfosdick8300]

So since amplitudes add by constructive interference when signals are in phase, how and where do we direct the input signal and the phase-shifted signal so input and output add together, thus doubling the amplitude at some circuit further down the line?

[@thetuberoaster8321]

An op-amp (or JFET) mixer (summer) with two inputs would probably work best. One input would be the phase shifted signal and the other would be the unaltered input. The output would be the result of the two waves adding together, yielding anywhere from zero to double amplitude depending on the pot setting.

[@tomfosdick8300]

@@thetuberoaster8321 Thanks for the reply but if amplitude doubles aren't we talking about free energy? Couldn't we just continue doubling like a voltage multiplier as long as the initial signal kept coming into the circuit?

[@thetuberoaster8321]

​@@tomfosdick8300 Not really, you can double the voltage of the signal, but any power you get out will come from the power supply for the phase shifter transistor and summer op-amp if you use it. Even if you were to use diodes instead to make a sort of passive voltage multiplier, the power out would still be less than what is coming in.

[@rushikeshpandit513]

What is the range of input signal?? I mean at what extent we can raise input votage?? Can we give input of 230v 50 hz supply??

[@thetuberoaster8321]

This circuit would only work for small signals. The input can only go as high as maybe one quarter of the supply voltage and not clip. The supply voltage would need to be a very high voltage and the transistor and capacitors would have to be rated high enough to handle that. The other problem is that the output impedance would be high, requiring another amplifier after to deliver any sort of power. To phase shift mains power, you'd be better off using big inductors and capacitors. It would be hard to make it variable.

[@tomfosdick8300]

My objective is to so arrange circuitry that the ambient RF constantly present in our atmosphere can be "harvested" in such a way as to gather free energy.

[@thetuberoaster8321]

Free energy is possible to obtain but not with this circuit. Using opposed coils you can get the waves to clap together in such a way to get basically free energy. The Mr. Preva Experiment demonstrates this phenomenon and is a good place to start. I don't post about it here because it's apparently controversial.

[@tomfosdick8300]

Thank you Tube Roaster I will go look at Mr. Preva. Again, I appreciate your straightforward answers and clear explanations. @@thetuberoaster8321

[@alephjesusqrst]

cycle the phase shift, say one phase shift every 5 seconds

[@MechanicForGMCCars]

excelent video thank you that circuet might by usefull for pick up coils in distributor I am plagued for years with my hei ignition system basicali that thing has no advance or retard option for ignition timing very usefull circuet how ever Im not shure if it wuld work on my circuet I did in the past use only 500k pott betwean pick up + lead and input on the 4 pin gm ignition module and indead it was nearli 180° out of phase fiering how ever I did not use voltage deviders or capacitora engine run crapy honestli but it did fire at exaust stroke engine did run at exauat stroke how ever after half houer cranking engine and the problem by my was I used speaker wire was an fool didnt have any non resistive leads. Only problem I have I dono what resistor value to chuse or capacitors or resistors the pick up coil is mostli based on voltage and high frequency I ques around 33hz up to 333hz max thats how much is rated the 555 timer in the ignition module it uses the mc 3334 ic chip set . So any suggestions what transistor potentiali wuld work on that set up or activateing or useing that circuet with an darlington power transistor???