A small, simple AM receiver project. This AM receiver can pick up medium wave stations in your area
This circuit can use general purpose transistors, and in this example there are 3 BC109C transistors. In this schematic and BOM there is a 200uH inductor and a trimmer 150-500pF capacitor, though these parts can be salvaged from an old AM radio, to preserve the directional nature of a tuning coil, and an adjustment knob (plate capacitor) that work well for radio reception.
The 120k resistor is for regenerative feedback between the Q2 NPN transistor and the input to the tank circuit. The value of this resistor is important to the performance of the entire circuit. In fact, it may be better to replace the fixed value with a variable resistor paired with a fixed resistor to adjust the oscillation and sensitivity of the circuit. All the connections in this circuit should be short to minimize interference.
Performance of the circuit will vary depending on stray capacitance in your layout, the inductor winding/core/length, etc. Changing values of some of the capacitors, or adding them, as well as a potentiometer in the feedback loop can help with the performance of the receiver. With such a small circuit that is affected so much by its construction and its environment, a lot of hand tuning and experimentation will be fun, instructive, and possibly necessary to make it work best.
Simple AM Receiver Project - [Link]
This is the first book of Giorgos Lazaridis covering the BJT Transistor Theory. The purpose of this book it to help the readers understand how transistors works and how to design a simple transistor circuit. It is addressed to amateur circuit designer with little or no previous knowledge on semiconductors. The book is written to be easy to follow, so it keeps mathematical formulas as simple as possible. Feel free to download and read it. More topics will be covered later.
The BJT Transistor Theory - [PDF]
Hemal Chevli blogged about his transistor tester project:
It has mega-8 as the brain, lcd to show specs of the transistor like which pin is which, what type of transistor it is eg NPN,PNP, N-MOSFET,P-MOSFET, etc., many components can be tested like different types of transistor, diodes, resistors etc, the good thing about this is that it also shows which leg is which, no need to open the data sheet
Transistor tester project - [Link]
TraId – is a Transistor type & pinout identifier:
TraId is a really low cost version of the Part Ninja. It’s made to only identify the pinout and type (NPN/PNP) of a transistor and display the results on eight LEDs. Currently the firmware only handles BJTs but I think FETs should be possible as well.
TraId – Transistor type & pinout identifier - [Link]
These recent breakthroughs in electrical component technology are likely to have a significant impact on the electronics industry – and on people’s everyday lives.
Your’e probably aware of the superstar conductor of the future, Graphene: “A wonder material that is the world’s thinnest, strongest and most conductive material with the potential to revolutionise diverse applications; from smartphones and ultrafast broadband to drug delivery and computer chips”.
New electronic components will change lives in 2014 - [Link]
Fully depleted silicon transistor are much promising for future developments. Xavier Cauchy writes:
To date, transistor scaling has continued in accordance with Moore’s Law down to 32 nm. Engineering challenges, however, are forcing chipmakers to compromise performance and power efficiency in order to reach smaller nodes – unless they switch to new technologies that help better solve these challenges. Today, the semiconductor industry is starting to deploy such new technologies, largely relying on “fully-depleted” transistors for continued scaling and performance gains.
Fully depleted silicon technology to underlie energy-efficient designs at 28 nm and beyond - [Link]
Raju Baddi writes:
Bipolar junction transistors transfer a current from a lower-resistance emitter to a higher-resistance collector. You can use this property to measure inductance by connecting a series inductance/resistance circuit in the emitter and biasing on the transistor long enough for the current to reach a maximum value that is at least five LR time constants. When the transistor’s off time is equal to its on time but is still biased by a silicon diode, the LR current decays exponentially toward 0A. Using the transistor’s current-source property, you can measure this current without hindering the decay process in the LR circuit.
Use a transistor and an ammeter to measure inductance - [Link]
Happy birthday, Transistor becomes 65 - [via]
The transistor, the ubiquitous building block of all electronic circuits, will be 65 years old on Sunday. The device is jointly credited to William Shockley (1910-1989), John Bardeen (1908-1991) and Walter Brattain (1902-1987), and it was Bardeen and Brattain who operated the first working point-contact transistor during an experiment conducted on 16 December 1947.
Yet this now ubiquitous device – these days more as an element in silicon chip design than as a discrete component – has a history that goes back to the mid-1920s.
Happy birthday, Transistor becomes 65 - [Link]
A Curve Tracer is a Device which will show the Voltage / Current dependency of an electronic part. It is therefore suitable to discover characteristics of electronic parts – and to quickly check if they are o.k. – or if the smoke left already.
It offers a current limiter, and a base/gate Driving Section.
Transistor Curve Tracer Project - [Link]
Ferdinand added a dc/dc converter circuit to the transistor tester, allowing it to be powered from 2 AA batteries instead of a single 9volt. This project is similar to our Part Ninja, it’s designed to test various electronic components like transistors, diodes, resistors, etc, and display their pin out and basic specifications. [via]
I built my own version of this handy tool last weekend. I replaced the linear regulator with a small boost-converter. Now the circuit can be powered with two AA batteries.
The PCB is sandwiched between the battery holder and LCD, so to provide a handy device without need for a case. I had a lot of fun designing and building the circuit, so thank you DP for highlighting this project.
Transistor tester powered from 2 AA batteries - [Link]