Adding frequencies together from coils

[orm2]

Adding frequencies together from coils:

If I have two coils( these are on an alternator) and they are both producing the same voltage at the same frequency (say 10Hz) with no phase difference between then, When these two coils are connected in series will the frequency now be 20Hz or still 10Hz.

i.e. when a number of coils are producing a frequency (all the same phase) and they are connected in series, what happens to the frequency?

Thank you

 

[sreid]

The answer is 10 Hz. Signals added together are just the sum of the individual signals. To get new frequencies the signals need to be multiplied together in some fashion (sum and difference mixer products for example).

 

[analogkid2digitalman]

orm2:

Yes, 10Hz, the voltage will be the sum of the 2 coils, current limited to that of 1 coil output.

If wired in parallel, again 10Hz, voltage limited to that of 1 coil output, current capacity doubled.

Basically equivalent to a center tapped transformer.

 

[GOTWW]

Yes 10 Hz. Even if they are at random phase angles. I got very confused once, thinking about digital or analog delay devices for music. Nomatter how much delay, the vector summation always held up to the same frequency. Apparently the delay needed to be longer that the note being delayed.

 

[logbook]

You mentioned an alternator. If these coils are each fed to their own diode (rectifier) then you do get an increased ripple frequency on the resulting DC waveform when the coils are phase shifted relative to each other. This is a multi-phase rectifier. This principle is important for high power systems where the required capacitor would otherwise be enormous. With enough phases, the need for a smoothing capacitor is eliminated.

As a simple question of just adding phase shifted voltages together, all previous respondents are correct.

 

[orm2]

Thank you very much for all your replies, that’s sorted that one out!

 

[peebee]

Yup yup yup.

The only way to get a higher-frequency response than you had from your original input signal frequency is to throw in some non-linear devices (like diodes as mentioned by logbook). Any frequencies you get that way will always be harmonics - integer multiples of the input fundemental frequency (20, 30, 40, 50, 60. . . Hz in your example with a 10Hz fundemental).

If you have all linear devices (resistors, caps, inductors), output frequency will always equal input frequency, the only possible changes are magnitude and phase shift.

No way to get lower frequencies out (5Hz, for example), using analog circuits -- not so far as I know, anyway -- you'd need some kind of logic device to do that.