1/17/2024 0 Comments Cheap transistor radiosThat’s one of the reasons the superhet technology had reached a dead end, also, I think.Īdding more and more transistors (double super, tripple super etc) just increased self-noise, without much (any) benefits in practice. Posted in Misc Hacks Tagged jfet, mosfet, transistor Post navigation Because of their high input impedance, FETs are common in things like non-contact voltage sensors, theremins, and guitar pre-amps. If you want take on FET technology, we have videos, too. There’s a second part of the video forthcoming, and we’re sure it will be worth watching, too. We liked that in addition to some theory and graphs, he also wired a FET on a breadboard and showed things like what happens when you cool the device down. video will tell you a lot about the practical aspects of these versatile devices. Of course, there are drawbacks, too, so it is important to understand the strengths and weaknesses of each technology. ![]() However, FETs eventually got better, boasting both very high input impedance and simplified biasing compared to bipolar technology. ![]() They had problems, so interest waned in the technology while the industry focused on bipolar transistors. While there were a couple of working FETs created between 19, the first practical devices didn’t appear until 1953. In 1948, the bipolar junction transistor hit the scene and changed everything. William Shockley tried and failed to make a working FET in 1947, the same year the first point-contact transistor appeared, which was invented while trying to create practical FETs. The idea for the FET is rather old, with patents appearing in 19, but there were no practical devices at either time. takes a decidedly practical approach to JFETs in a recent video that you can watch below. One uses a gate separated from the channel by a thin layer of oxide (MOSFETs), and the other - a junction or JFET - uses the property of semiconductors to deplete or enhance carriers in the channel. What they were looking for was actually the FET - the field effect transistor. It uses a small current to modulate a larger current, acting as a switch. ![]() However, what they first found - the bipolar transistor - doesn’t work the same way. Tubes used an electric field to regulate current flow, and researchers wanted to find something that worked the same way without the drawbacks like vacuum and filament voltages.
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