This is handy in case you need line-level circuits when tapping from existing lines, or want to use high-sensitivity at the input so that you do not degrade the original signal. Typical gain for these circuits is 40,000.
Typical range is 5Hz-200 MHz, although I can get upwards of the GHz band for this design, with similar available components, but filtering is not guaranteed at ultra-high frequency levels.
Designs are made to power levels up to 250mW (typical for most components), but can be up to 500mW.
I also do basic op-amp amplifier design as well as transistor & crystal oscillators, so feel free to ask about those, too!