acsignal
I'm taking an introductory electronics class, the first chapter is about amplifiers, controlled sources, gain, stuff like this. They mention "small AC signal" a few times but never explain what small mean and why there is the need to talk about "small" signals in the first place.
Anyone knows?
Thank you very much
Your appliance failures may well not be maians spike related.
Fitting surge suppressors to your outlets where expensive equipment is used sounds like an extremely good idea. These can be relatively cheap and a DIY solution is to use MOVs which are as good as many cheaper commercial offerings.
Below is a circuit and description from patent GB2231672
This is "a bit basic" but could potentially do an OK job of doing what you want.
A detector for detecting spikes on a mains electricity supply and for counting the number of spikes occurring during a period of time includes a zener diode (Z2, Z3) connected in series with a resistor (R4) and a counter (IC1) having an input connected across the resistor.
The zener diode and resistor are connected in series to the mains supply and the zener diode has a breakdown voltage of a magnitude such that under normal conditions it does not breakdown but upon occurrence of a spike in excess of a predetermined magnitude the zener diode breaks down and provides an input to the counter.
This interesting combination circuit from here detects spikes in a similar manner to above but also adds "flutter" and noise". They drive LEDs but you could add a counter or other monitor. Note that unisolated connections to mains can kill with ease.
The emitter follower, because of the negative feedback is pretty linear amplifier and is used for large signals all the time. Of course, if you want it to be even more linear, some special schematics have to be used but it actually depends on the application.
Also, the emitter follower has voltage gain less than 1 but the current gain is pretty high and as a result it is amplifier.
In your question you didn't specify what exactly the signal and load is, but on 10Vp-p and 50ohms of load, you probably will need some push-pull emitter follower as a power stage.
Best Answer
Small signal is relative term. When non-linear device (for e.g. transistor) is DC biased, it stays fairly linear in small region around the bias point. Small signal is the one that fits in the linear region.
http://en.wikipedia.org/wiki/Small-signal_model