Connect two frequencies without mixing?

Question

I want to connect 50Hz signal with a 120kHz signal (both in 5V).How can i connect them without mixing? what kind of devices
do i have to use?

I want to couple 50Hz signal with a 120kHz signal, transmit and at receive end, i want check whether 120kHz signal is present. can i get them without mixing?

Answer 1

I assume that you are trying to send the 50hz signal using the 120khz signal as a carrier since you use the words transmit and receive.

Impressing information upon a carrier whether it involves radio waves or not is called modulation and there are several ways to accomplish it.

However there are far too many methods to describe here but FM, AM, are some of the most well known modulation schemes.
Without looking at the equations I cannot say for sure but FM is slightly less complex when talking about what is going on physicaly with the circuitry although the circuitry itself is actually simpler for an AM circuit.

Mixing will only accomplish the creation of harmonics which does not mean anything since you would have to have a mixer at the other end to retreive (demodulate) the 50hz signal that you want to send.

If you want to send both signal to another place and simply see if they are present then just use filters to filter out the one that you dont want.

If you are just testing for attenuation then just look at the voltage levels of the different frequencies at the receiver point.

Answer 2

Opamp outputs are very low impedances. Connecting two together will not work well because of that, and because the outputs are ususally used for feedback, and each opamp will try to null out the other. Best to use two resistors, perhaps 1k-10k, to make an adder. Now you may need another opamp as a buffer, or the capacitance of a long run will modify your signal. Separating is a lot more difficult, involving two analog filters and their design. If the frequencies are close to each other, it can be a difficult design. Better to run a second wire. .

Answer 3

That depends on what you want to do with the "connected" signal. If you just hook the two wires together, you'll get a lot of weird interference between the two signals, but that may be what you want. You really need to be more specific with what you're trying to do.

Answer 4

What are you trying to do?

Answer 5

???
What means 'connecting'?

Doug