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23 Jul 2014


electronics-diy shows you how to easily make a mini FM transmitter:

It transmits FM waves so you could easily receive the signals on your mobile phone, radios, etc. As the name and the picture indicates it is very small and is approximately the size of a 9v battery clip. With this FM transmitter you could start your own mini FM station. The circuit uses BC547 transistor to amplify the signal and then frequency modulate it. It uses “frequency modulation” most commonly known as FM, the same principal to transmit audio signals captured by the microphone.


Mini FM transmitter - [Link]

22 Jul 2014


by Peter Demchenko @ edn.com:

Low-current switching regulator ICs often use a Darlington as the output switch. The power conversion efficiency in this case can be improved with the help of only two cheap components. To make this possible, the chip should have a separate pin for the collector of the driver transistor Q1 (Figure 1). At startup, D1 forms a path for the collector current of Q1. Later, D1 and C1 comprise a current-additive rectifier which enhances the collector voltage and current of Q1, hence reducing voltage drop on the closed switch Q2.

Improve efficiency of low-cost switcher - [Link]

16 Jul 2014


by Henrik’s Blog @ hforsten.com:

In my previous post I wrote about a circuit that would change it’s output depending on what was the spice simulations DC sweep range. Today I investigated the circuit a little and I was able to remove lots of components that didn’t affect the bug and this is the resulting circuit.

Metastable transistor circuit - [Link]

4 Jul 2014
Four carbon nanotubes transistor channels are all controlled by the same local back gate.

Four carbon nanotubes transistor channels are all controlled by the same local back gate.

IBM has given itself a deadline of 2020 to perfect the nanotube transistor, for which there are significant technological hurdles: R. Colin Johnson @NextGenLog

IBM Will Produce Nanotube Transistors by 2020 or Give Up - [Link]

11 Jun 2014


by Benabadji Noureddine:

This Design Idea demonstrates a new method of driving six LEDs with only two I/O lines from a microcontroller, and so is particularly suitable for any pin-limited chip. It uses a pair of I/O lines combined with a pair of complementary bipolar transistors. More than one LED can appear to be lit by multiplexing.

Two PIC pins drive six LEDs - [Link]

9 Jun 2014


by University of Twente:

Researchers from the University of Twente MESA+ research institute, together with the company SolMateS, have developed a new type of transistor to reduce the power consumption of microchips. The basic element of modern electronics, namely the transistor, suffers from significant current leakage. By enveloping a transistor with a shell of piezoelectric material, which distorts when voltage is applied, researchers were able to reduce this leakage by a factor of five (compared to a transistor without this material). An article presenting the prototype of the transistor appears in the June issue of IEEE Transactions on Electron Devices, an authoritative scientific journal in the field of transistor research.

Prototype of new transistor for lower power consumption - [Link]

7 Jun 2014

In this episode Shahriar presents a tutorial on the design and characterization of a single-stage low-noise bipolar amplifier suitable for audio applications. Given a set of specifications, a common-emitter topology is investigated. The circuit employs a beta-insensitive biasing scheme which is simultaneously optimized for maximum output swing. The small-signal gain of the circuit is calculated and the bandwidth is set for audio frequencies. A non-inverting operational amplifier is used as a second stage to achieve the desired overall gain. The circuit is assembled on a breadboard where the gain and bandwidth are measured and compared with design specifications. As the final experiment, the circuit is used to amplify signals from a microphone.

Tutorial on the Theory, Design and Characterization of a Single Transistor Bipolar Amplifier - [Link]

28 Mar 2014


Our beloved silicon-based transistors can “only” work at temperatures up to 550° F (around 290° C), which is much more than what’s needed for most general-purpose applications. But those don’t include a nuclear reactor, obviously! (Unless you have one at home. Do you?)

University of Utah engineers have developed tiny plasma-based transistors that can withstand temperatures up to 1,450° F (almost 800° C) and work with ionizing radiation. Since plasma itself is ionized gas, it can even be said that nuclear radiation contributes to proper functioning of these devices. Besides, current plasma-based transistors are about 500-µm long, while these newcomers measure 1–6 µm (!).


[via Elektor Electronics]

March 20, 2014 – University of Utah electrical engineers fabricated the smallest plasma transistors that can withstand high temperatures and ionizing radiation found in a nuclear reactor. Such transistors someday might enable smartphones that take and collect medical X-rays on a battlefield, and devices to measure air quality in real time.

“These plasma-based electronics can be used to control and guide robots to conduct tasks inside the nuclear reactor,” says Massood Tabib-Azar, a professor of electrical and computer engineering. “Microplasma transistors in a circuit can also control nuclear reactors if something goes wrong, and also could work in the event of nuclear attack.”

Tiny Transistors for Extreme Environs - [Link]

23 Mar 2014


Kerry Wong writes:

Transistors operating in their avalanche regions are often used to generate fast rise pulses (see avalanche pulse generator using 2N3904). Many transistors can also avalanche when the connections to collector and emitter are reversed. When operating in reverse avalanche region, these transistors are sometimes referred to as negistors.
Because the asymmetry and doping differences between the base-emitter and base-collector junctions, the avalanche voltages for reversely connected BTJs are usually magnitudes lower than their normal avalanche voltages. Here, I decided to test a few different transistors and see at what voltages the reverse avalanche occur.

The circuit I used is a simple LED flasher, similar to what was described here. As with any circuit that exhibits negative differential resistance, the principle of operation is quite simple. The capacitor is charged via a current limiting resistor…

BJT transistor in reverse avalanche mode - [Link]

15 Mar 2014

Bill uses a replica of the point contact transistor built by Walter Brattain and John Bardeen at Bell Labs. On December 23, 1947 they used this device to amplify the output of a microphone and thus started the microelectronics revolution that changed the world. He describes in detail why a transistor works by highlighting the uniqueness of semiconductors in being able to transfer charge by positive and negative carriers.

How the first transistor worked - [Link]





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