I'm looking for something (IC, small circuit) like a switch or transistor, which can be controlled by a digital, analog or any other kind of signal. I want to connect a few of these to the signal output and depending on the signal the "switches" turn on or off.
It is a very abstract idea and I have no clue how to archive that. The solution should be small and cheap.

 

That is far to vague to give any kind of practical solution.
Details are needed.
Max.

 

Too abstract for any suggestions.
Need:
Voltage - Magnitude and AC or DC
Current Maximum
Do you need isolation between the control and the switch output?
How fast and how often do you need to switch?

 

I'm looking for something (IC, small circuit) like a switch or transistor, which can be controlled by a digital, analog or any other kind of signal. I want to connect a few of these to the signal output and depending on the signal the "switches" turn on or off.
It is a very abstract idea and I have no clue how to archive that. The solution should be small and cheap.

Any kind of signal? The sun at high noon? Water overflowing a stream's banks? A rooster crowing?

What is "small"? A breadbox? A matchbox? A dime? A decimal point on a printed page?

What is "cheap"? A thousand dollars? A dollar? A cent? A thousandth of a cent?

Your description is WAY too abstract for any meaningful discussion?

 

And, "for any kind of signal". Ambitious to say the least.