Gainclone is a single integrated circuit based on an operational amplifier (op amp) on a single substrate of silicon. The LM3875 is the "weapon of choice". This great chip, is a little larger than the size of a thumbnail and can deliver up to 56W RMS continuous with 100W peaks and it can do this at 0.05% distortion! Because they are DC amplifiers (DC coupling right through the amp) they can go all the way to 400kHz! The first chipamp I built was a pair of monoblocks. Though these are a little industrial looking, they deliver big time.

Build your own LC Meter and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils. LC Meter can measure inductances starting from 10nH - 1000nH, 1uH - 1000uH, 1mH - 100mH and capacitances from 0.1pF up to 900nF. The circuit includes an auto ranging and "Zero Out" function to make sure the readings are as accurate as possible ... [more]