The format of the talksThe talks will be semi theoreticalSpeakers should be available for discussions afterwards or on other weeksSome will want a deeper understandingOthers just want to use technology confidently
Practical examples will be used where possibleSuitable group projects will be identifiedAnonymous feedback forms will be used
Reference designsIn order to retain our focus we will regularly refer to the circuit diagrams of two kits.The BITX20 and the SoftRock 40/80m.
BITX20 Picture from Hendricks QRP Kits
It’s a fairly simple transceiverIt uses few circuit variationsIt does not use software Why the BITX20?
We will learn to break down “big” circuit diagrams (next)Don’t Panic!
We will learn to break down small circuit diagrams even smaller.(Another day)
SoftRock RxTx 40/80m Picture from Nicolas M1HOG.com
It uses a range of circuit variationsIt is a more modern designIt introduces digital techniques Why the SoftRock RxTx?
Many of the same principles are used in the: The SDR Transmitter(avert your eyes for now if you like)
These circuits were just to set the scene.We will come back to them during the following talks:-
FundamentalsCurrent, voltageConductors, resistorsPotential dividersKirchoff's laws
Signals & test equipmentDC / ACSignal GeneratorsGraphs, Time, Amplitude, Frequency, Phase(using visualisation tools)Oscilloscopes (practical to follow)RC Bridges & Grid Dip Oscillators
Electric and Magnetic FieldsElectric fields, capacitorsMagnetic Fields (Using visualisation tools)Magnetic Materials, Inductors and Transformers (Bifilar winding, Baluns)
Analogue circuit designDiodes, Transistors (Bipolar, FET), ValvesTransistor circuits: Common emitter, emitter follower, common base, biasing, feedback.Transistor pairs: Cascode, long tailed, mirror.
Introduction to integrated circuitsICs are not scary: lets look insideOperational amplifiers & their internal designGates, flip-flops, transmission gates
The first commercial op-amp, the K2-W 1952 http://www.ieee.org/portal/site/sscs/menuitem.f07ee9e3b2a01d06bb9305765bac26c8/index.jsp?&pName=sscs_level1_article&TheCat=2171&path=sscs/07Fall&file=Lee.xml
Analogue signal processingSuperhet (supersonic heterodyne) receiversMixers (multipliers). Single / double balancedFilters (RC, RC active, LCR passive)Filter design with passives or op-amps
Electro Magnetic Fields (e.g. radio waves)Transmission lines / coax cablesPropagating EM FieldsFundamental Antenna theory (dipoles)Antenna matching / tuningPhased arrays / Yagis
Digital signal processingDigital Communications e.g. PSK31A/D & D/A, Shannon’s law, sampling theory Some more logic circuitsDirect Digital Synthesis (DDS)Digital filters and their design
Demonstrations of digital signal processingThese will be non-theoretical demonstrations of signal processing using a Field Programmable Gate Array (FPGA) demo system.If interested this can be followed up with more detail and a live demonstration of programming