What's New

FEB 26

I've just discovered that most of my own Sinclair ZX Spectrum programs, which are available to download, cannot be loaded using the emulators Qaop/JS & JSSpeccy3, running in Chrome and Firefox, under Ubuntu-based Linux. However, all is OK using the Free Unix Spectrum Emulator (Fuse). Is this a recent issue or did I not test properly at the time, I wonder?

The ones that work OK seem to be those where I didn't renumber the lines of code as described here. So, renumbering seems to have messed things up, but not for Fuse - very strange! It was a convoluted process involving Fuse with scope for problems in retrospect. I'd like to understand what has happened, but for now have uploaded the un-renumbered programs instead. In addition, all programs are now contained in a single file, rather than as separate downloads.

JAN 26

I have rediscovered a very old blog of mine that never got going and is better suited than here for small posts, so I am now using it for that purpose.

DEC 25

Vintage Binary Elecctronic Adder & Counter Project

Spurred on by memories of a large electronics project from my school days, there are two new pages: one about the project and background and one about the NOR circuits behind it.

JUNE 25

Ladybird Radio

I decided to temporarily replace the ferrite-cored coil with an air-cored one from a very basic crystal radio. that has no variable capacitor and is tuned instead by changing the length of the coil, and hence its inductance, by means of a nail attached to a wire. This in effect provides a tapping point that I was able to use for the Ladybird radio, so after connecting the coil to it, I just held the nail firmly for a good contact near the output end of the coil and tuned the radio the normal way. It  worked just fine, unsurprisingly, both with and without regeneration.

I did try to use this coil without a tuning capacitor and tune the Ladybird radio by moving the tapping point, but was not successful, presumably because I was changing the inductance of both sections of the coil between the tapping point and coil ends.  What is needed is a second, stationary, tapping point to fix the length of the output part of the coil. Will add to my to-do list...

MAY 25

Ladybird Radio: new picture showing the changed transistor biasing to the first audio stage transistor and a resistor to eliminate the potentiometer that isn't being used.

JUL 24

Some thoughts on a basic radio telescope project for the amateur inspired by memories of one in the 1970s.

JUN 24

Various recent updates to Ladybird Radio, including a possible explanation for its quirky design and a recent mod which means R5L can be easily received without using regeneration. Smooth Radio now also gone from AM in the UK. Also on the reception of SW on the Transistorized Crystal Radio. 

MAR 2024

Ladybird Radio - update to stations received; also to comments on the explanation of regeneration in the book. Highlighted in bold.

FEB 2024

Ladybird Radio - update/correction to stations received - including Radio Caroline :-) - and some comments on the explanation of regeneration in the book. Highlighted in bold.

JAN 2024

Now getting the laser communicator to work with a higher gain amp.