Author: Andrew
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Testing v8.1 of the BJT Transistor Experimentation Board…
…with a Colpitts oscillator setup. – See the schematics in the images. Version 8.1 adds: * Optional Vcc+ supply filter using resistor, ferrite bead or inductor * Collector resistor split for gain boost experiments * Additional feedback network for common collector stages * Extra ground point for cleaner external feedback wiring Everything worked as expected.…
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The Class AB Amplifier explained on a conceptual level
Based on the Motorola Application Note AN-422 Many classic audio power amplifiers from the 1970s and 1980s were built around a small collection of elegant circuit techniques that remain relevant today. One such example is the Motorola AN-422 Class-AB amplifier topology. While schematics of these amplifiers are widely available, understanding why each section exists is…
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BJT Transistor Experimentation Board – Version 8.1 Released
I’m pleased to introduce Version 8.1 of the BJT Transistor Experimentation Board. The new board is now available here: https://ufelectronics.eu/product/common-emitter-collector-amplifier-board-v8-1/ Although Version 8 has proven to be a useful platform for experimenting with common emitter and common collector transistor circuits, practical use and continued development revealed several opportunities for improvement. Rather than redesigning the board…
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Connecting Sponsors with Engineering Education
Support engineering education – or bring PCB-based hands-on learning into your course Electronics education becomes significantly more effective when students work with real hardware instead of only simulation. That is what this is focused on. I am providing PCB-based learning modules for universities and technical education. These are PCB-only boards with a semi-schematic layout that…
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The Symmetric Wilson Current Mirror – Free KiCad PCB Design Files
Get the free Kicad PCB design files of the Symmetric Wilson Current Mirror – And start build your own for your DIY audio projects. Get the Kicad files from Github, and order where you want : (Both versions available. Future updates too.) https://github.com/ufelectronics/Symmetric_Wilson_Current_Mirror – Or order directly from PCBWay : (Plain version, without…
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Motorola Class AB BJT Amplifier – Free PCB design Downloads
Build and experiment with the Motorola BJT Amp discussed on my LinkedIn profile back in November and December. Download the KiCad files for free from my Github repo: https://github.com/ufelectronics/classAB-motorola-PCB-layout If you missed it, I once shared the KiCad file for simulating the Motorola AN-484A transistor amplifier. Now I’m sharing the KiCad files for…
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Free KiCad schematic for a 50W to 145W Audio Power Amplifier
This is a basic high power audio amplifier constructed by Bob Cordell. Understanding this audio power amplifier sets the ground for understanding high power, transistor based audio amplifiers. – That is my experience. In his book ‘Designing Audio Power Amplifiers’ you will find detailed explanations on how the various parts of it work. – Very…
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Uneven DIY coils for RF are a past
Winding them with bare copper wire: * They won’t get an even distributed spacing * Handling them, changes their inductance * They partly uncoil again, as you let go Nothing is controllable. Until you take duct tape, alias ‘Panzer-tape’, alias Gaffa and what else you call it. Take a random object with the desired diameter.…
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Measuring Inductance or Capacitance without an LCR-meter
You have a DIY inductor and no LCR-meter at hand? – No problem. A known resistor in series, and some calculations make the day. L = R * sqrt(3) / ( 2 * π * f ) Example Measurements: * R1 = 99.82 Ω * Vout = Vin / 2 at 901 khz ( 901,000 Hz…
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Free KiCad schematic for a BJT based LC Colpitts Oscillator, 5 – 8 MHz
This oscillator is based on two transistors. No crystals, by purpose. It can oscillate on various frequencies between 4.8 MHz and 8 MHz. With a variable capacitor (around 15 – 400 pF) instead of C2, you can dynamically vary the frequency in parts of that range. Its functionlity is verified by real world build and…