Last updated:24-8-2015

Visitors since 2001:

Professional engineering is the top, but amateur engineering is more fun.
It is when you cross the barrier between these two, that things become really fascinating!

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Latest news

Theory, information and tutorials
Natural radio
Electronics and RF techniques
Circuits and Projects
Poor man's laboratory equipment
Online software

Mechanical work
Places that I have visited
Useful Links
How to contact me
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micro SD locker and instructions for a safe PC


Read this for your safety!

 My sponsor since 13-8-2015:

Have you got any old unwanted electronics?
Plain PCBs, failed projects, old radios or any other damaged electronic equipment.
Donate them to someone who really cares about these.
Post them to me and I will undertake all shipping costs!

Theory, information and tutorials

Assembly tutorial and information (Tutorial, my notes, my programs for the PIC)
Diodes evaluation for crystal sets - A simple test
Mechanical excellence - A tribute to the watch movement
Mechanical excellence - A tribute to the wind-up gramophone engine
Linear UHF vacuum tube circuits
Vacuum tube television
General diode applications
Passive crystal receivers
Tunnel diodes
Varactor diodes
Schottkey diodes
Rectifier diode audio amplifier
Passive DSB transmitter
Passive CW transmitter
Ferrite core mixers
Magnetic amplifiers
Electromechanical transmitters and receivers
Neon lamps
Radar history
The phasitron tube
Thermoelectric generator
Analog computers
Logic gates technology
TV transmitters
SSB transistorized CB
Barlow Wadley loop
Radio spectrum frequency allocation chart
dBm, mw, Vpp, Vp, Veff conversion table
Optimum wire size for RF coils
Observations on ferrite rod antennas
Designing wideband transformers for HF and VHF power amplifiers
Crystal parameter measurement and ladder crystal filter design
Quartz crystal parameter measurement
Crystal filters with variable bandwidth and constant center frequency
Ultra low noise active devices on a budget
A simple and good program for mechanical and architectural design.
74LSxx series chips internal schematics
Common varicaps in radio
RF mixers explained. Part 1, part 2 and part 3.
Understanding mixer products
Harmonics generation using step recovery diodes (HP)
Understanding noise types in oscillators
IARU region 1 VHF and up band plan
IARU region 1 HF Europe band plan
IARU region 1 HF band plan

Natural radio
The sounds of the earth and other natural sources and simple equipment
E-field VLF natural radio receiver
H-field VLF/ELF/ULF natural radio receiver (in development)

Electronics and RF techniques SV3ORA
An adaptable crystal set that has it all?
Homebrew your own SiC LED
Reliability of data storage media
A generalized prototype board for digital electronics work
The simplest way to program and read the PIC16F84 MCU

Measuring and selecting the actual received frequency in regenerative and direct conversion receivers
Ultra narrowband adjustable shape and bandwidth crystal phasing filter
How to draw ARRL-style schematics
Making precision PCB coils
Experiments on circuits on paper - Dwawn resistors

Circuits and Projects

Digital electronics

micro SD locker and instructions for a safe PC (Greek only)
A single chip micro-computer for the lab
A universal variable VCO clock
Reverse linear ramp, sawtooth generator
Core rope memory
Coincident current NOR gates
Experiments on square loop toroids
A transistorized 4-bit digital computer made out of discrete DTL
(in development)
A full-sized microcomputer inside a keyboard

Development of a Tele-control Home Appliance Controller (my MSc project) First pages, Main report, Schematics and datasheets
A simple, failure immune 4-bit digital computer made out of common TTL chips (in development)
The ZX-80 computer (A useable home computer built REALLY from scratch. This includes PCB etching)
The Jupiter Ace computer (A useable home computer built REALLY from scratch. This includes PCB etching. I
n development)
Reverse engineering of the Vectrex system (The unique vector graphics system and how to build one yourself from scratch)
The homemade PC-XT project (A greater scale PC-clone home computer. Some parts are in KIT form.
In development)

RF electronics

High dynamic range broadband LNA for handheld transceivers
HF directional coupler
Broadband CW QRPp HF transmitter
Ultra low noise, low distortion, general purpose LF/MF/HF oscillator
All HF bands low distortion sinusoidal XO
The ultimate QRP HF transceiver
A simple, good quality UHF TV modulator
The S53MV ZIF microwave transceivers reborn

An easy to build all HF bands discrete SSB transceiver
In-phase splitter/combiner
4:1 balanced to unbalanced balun
10GHz gunnplexer (in development)
Magnetic receiver (in development)
Fine tuning the SM0VPO HF amplifier for better performance
An ultimate quality shortwave transceiver (in development)
The fully transistorized radio project
Smart KIT 1W FM transmitter reverse engineered
Single span, high spectral purity oscillator 3KHz-30MHz (in development)
A simple to assemble regenerative SW receiver

My 10GHz SDR phasing SSB transceiver
(in development)
HF all-band tuneable bandpass filter
1-30MHz deluxe crystal controlled CW/CDW transmitter
Ultra wideband sinusoidal VFO with AM capability
1-30MHz ultra low noise and distortion crystal oscillator
Control the transmitter from the computer
Coaxial built transverter for the X-Band

Audio electronics
My High Fidelity audio page

Audio compressor

Other electronics
High power thrifty regulator
Personal ballooning - A pioneer flying concept
Experiments for Energy Harvesting and Efficiency
A blinking LED Christmas tree
The LED Zeppelin game became the LED Zapper! (a game for the blind or the deaf)
The SkyNet project (Low data rate laser data links, 
in development)
The vacuum tube poly-synth project (VCO section)

Poor man's laboratory equipment (nice upgrades to your lab, at a fraction of the cost!)
A low profile lamp designed specifically for SMD rework
Poor man's HF spectrum analyzer
A BASIC computer designed especially for lab use (in development)
A low frequency circulator/isolator
A mini reference oscillator
A return loss bridge for impedance measurements (in development)
A mini dummy load for impedance measurements (in development)
Solid state UV PCB exposure (in development)
Semiconductor analyzer (For BJTs, mosfets and diodes. An Elektor project)
A homemade UV exposure box for big double-sided PCB fabrication

Software and software I have developed

DataText. Transfer data through any radio amateur text mode
The CDW communications mode (version 2)

JLab - an online electronics software suite

Mechanical work
A depth gauge or Z-axis meter for the Unimat-SL (DB-200)
Making a special screwdriver for the lab (under development)
A table for the lathe
How to mill an enclosure on a small lathe (part of another project)
Experiments on the olive oil fuel

Places that I have visited
A trip on a passive repeater
Rhodes island
Santorini island
Samos island
Lefkada island

Useful Links
Dc4ku website. Measurements and RF (only in German)
Great RF experiments website
S53MV website. Microwave and advanced RF projects.
JF1OZL website. Amateur radio projects.
Greek Microwave Group website. Amateur group for microwave radio projects.
YO3DAC - VA3IUL website. Amateur radio projects.
LA8AK website. Amateur radio projects
SM0VPO - G4VVJ website. Amateur radio projects.
Hans Summers. Radio, Electronics and Computing Projects.
QRP and SWL homebrew equipment.
Cool homemade stuff homemade components.
Reverse engineering simple equipment.
My professional website.
Elm Chan website. Great microcontroller projects.
Freddy Alferink website. All about accurate measurements.
Radio waves below 22KHz.
Simple QRP equipment
Homebrew electronics from Germany
Web SDR - Listen to DC-30MHz without an RX

How to contact me
The email to contact me is:


That is, sv3ora AT qrp DOT gr. Any feedback is kindly appreciated.

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You are free to copy and use everything on this non-profit amateur website. Note that for copyrighted material, you may need to ask for the authors permission first. All material on this website is provided as is without any guarantee. Many of the material is my own thoughts and do not necessarily represent the truth. It is provided for you to read in order to understand the basic principles of operation. If you find your material is listed somewhere in this page and you want to remove it or get credit for it, please let me know and I will remove it immediately or add relevant notes. You may copy and use any content of this website to other pages, only if you clearly include in your pages the source that it has been taken from (which is this website). You may build and use any project only at your own risk and you are the only one that are responsible for its use. You should always consider your country regulations before building anything.

* I am paying lots each year for maintaining this add-free non-profit website and you get that for free, please gain knowledge from what you find here and be reasonable about copyright stuff anyway. Contact me FIRST before you make any nasty post anywhere on the web about my website!