A Simple Method to Test a Field Effect Transistor for Defects Modern electronics use more and more FET’s. The reliability of their design has been proved by practice. This is why they are highly usable and effective in various types of household appliances. However, sometimes we have to repair them. In this case we often need to test a component for defects. For example, how do we check a field effect transistor soldered out of a broken assembly taken from a damaged appliance? The easiest testing method is to use a needle tester. On a good transistor the device shows infinite resistance between all its outputs with the exception of modern models that have a diode between the drain and source. This diode behaves just like a regular diode. The second testing method uses a modern digital multimeter. The black probe, which is negative, is applied to the transistor’s drain output. The red probe, which is positive, is applied to the transistor’s source output. The multimeter shows a direct voltage drop of about 450 mV at the inner diode. The other side has infinite resistance. At the moment the transistor is closed. What do we do next? We leave the black probe in place, apply the red probe to the gate, and then return it to the source output. The multimeter indicates 280 mV, ie it has been closed by the touch. Now, if we touch the gate with the black probe without removing the red one and return the former back to the drain output, the FET will close and the device will again …
The Field-Effect Transistor (FET) was first patented by Julius Edgar Lilienfeld in 1925 and by Oskar Heil in 1934, but practical semi-conducting devices (the JFET, junction gate field-effect transistor) were developed much later after the transistor effect was observed and explained by the team of William Shockley at Bell Labs in 1947. The MOSFET (Metal Oxide Semiconductor Field Effect Transistor), which largely superseded the JFET and had a more profound effect on electronic development, was first proposed by Dawon Kahng in 1960.
The field-effect transistor (FET) is a transistor that uses an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material. FETs are sometimes called unipolar transistors to contrast their “single carrier type” operation with the “dual carrier type” operation of bipolar (junction) transistors (BJT). The concept of the FET predates the BJT, though it was not physically implemented until after BJT’s due to the limitations of semiconductor materials and the relative ease of manufacturing BJT’s compared to FETs at the time.
This video demonstrates the fabrication of evaporation-free OFETs using the Ossila pre-patterned ITO OFET substrates. All layers are deposited by solution to enable rapid device testing with a mobility approaching 10-2 cm2/Vs achieved from transistors based on the organic semiconductor P3HT with a PMMA gate insulator and a PEDOT:PSS gate electrode. Website: www.ossila.com Product Page: www.ossila.com For more information please contact: email@example.com
Demonstration of real-time electrical characterisation of an Organic Field-Effect Transistor (OFET) sensor built on a flexible and transparent plastic substrate. This video shows the sensor’s behaviour under mechanical deformation and analyte vapour sensing. A work of Antonis Dragoneas and Martin Grell from The University of Sheffield, UK for FlexSMELL Marie Curie ITN of FP7. For more information on this project, please visit: http:///www.flexsmell.eu or contact: firstname.lastname@example.org
This is a replacement for Hall Effect Magnetic Circuit to properly include the schematic in the video. This is a circuit that uses a Hall Effect sensor to recognize a magnetic field and then either turn on or turn off a transistor that drives an LED. The part was purchased from Electronic Goldmine and I include an image of the sample circuit that they provide for using the sensor.
I recently bought two pedals from this fine chap named Jimmy (Lynessmy), who is based in Penang and makes fine guitar pedals. He has a list that’s VERY extensive on what he can build, and customise according to your needs. So I ordered a MOSFET boost (not a brand name, but rather a type of circuitry), as well as a Demeter “Fat Control” Mid Boost clone. I was very pleased with his patience, and being so courtuous to listen and give suggestions and overal professionalism. He sent updates on the build from time to time and does domestic shipping as well. The MOSFET (metal–oxide–semiconductor field-effect transistor) Boost yields so much headroom, adds life to your sound, and at about 2 o’clock starts to crank up and drives your signal. Sound very much like the guitar and had more than enough gain and level boost for any situation. The Demeter “Fat Control” Mid Boost Clone does what the name implies. It boosts up your mid frequency range (apparently around 200 – 500hz), and gives it more ‘honk’, and cuts through the mix. Extremely versatile pedal. (SIDENOTE: I actually requested if the Demeter Mid Boost could be forged in to smaller enclosure similar to the MOSFET Boost, since the original enclosure was bigger. With his magic and geniusness he actually did.) In love with these pedals, very impressed with Jimmy’s work, and i would definitely order some more pedals from him. If you’re interested you could contact him on email: pcb4diyeffects at gmail dot com Played with a …
demonstrations.wolfram.com The Wolfram Demonstrations Project contains thousands of free interactive visualizations, with new entries added daily. This Demonstration simulates the effect of an external bias on an MOS capacitor. The four plots show the electric field (F), the corresponding potential of the capacitor (V), the carrier density of the semiconductor from the junction through the depleti… Contributed by: Alberto Sottile Audio created with WolframTones: tones.wolfram.com
You’ll learn different techniques to test a Field-Effect Transistor such as the Junction FET (JFET), the Metal Oxide Semiconductor FET (MOSFET), the Unijunction Transistor (UJT), and the Programmable Unijunction Transistor (PUT).
MatLab simulation of the Vertical Organic Field Effect Transistor transfer characteristics. Top left image describes the current flow between the source electrode and the drain electrode under constant driving bias and varying gate bias. Other images present the charge concentration distribution inside the device from different points of view.