2) Replace the regulator with a switching buck regulator. This type of a regulator acts similarly to what would be a DC transformer (for reference, a real transformer can only operate on AC). The efficiency is very high so very little excess heat is generated, to the point where a heatsink is not n...

The RF output comes from the modulator. All the modulator does is to put the composite video signal onto a high frequency carrier. The main problem with the modulators and hence the RF output, is that these are analogue devices which use a capacitor-inductor to form the high frequency oscillator, so...

While on the subject of the early QL machines that were supplied with a dongle, does anyone have any good quality photos of the the populated board that they used? Or know of web site(s) that have such photos?

Mark

Where is that clapping emoji

Well done Urs

Mark

Have you tried it out yet? :) No :( Got to get a grip on the garden and other outdoor jobs while the weather is good... Got the solar system on the shed partly functional, and the 12V lights in the shed and the 'sun house' next to the shed installed, connected up and working. Tested them last night...

My Q68 arrived today :D https://qlforum.co.uk/download/file.php?id=1867 Q68 case front https://qlforum.co.uk/download/file.php?id=1866 Q68 case rear Thanks Derek https://stardot.org.uk/forums/images/smilies/eusa_clap.gif https://stardot.org.uk/forums/images/smilies/eusa_clap.gif https://stardot.org....

My Q68 arrived today :D IMG_7241.JPG IMG_7240.JPG Thanks Derek https://stardot.org.uk/forums/images/smilies/eusa_clap.gif https://stardot.org.uk/forums/images/smilies/eusa_clap.gif https://stardot.org.uk/forums/images/smilies/eusa_clap.gif Mark

martyn_hill wrote:Just loving the Gigatron!

I build it last weekend at an Acorn meet up. Pictures of it just after I powered it up are here

Mark

I was busy building this:

This was at an Acorn meet up.
There are full resolution 'photos (and the lower resolution 'photos) on my Flickr account here.

Mark

This makes more sense now on the switch side of things. The switch enable will trigger that lower of the 3 comparator's (there are 4 in the 339 package), and that in turn will switch Q6 on, allowing the SW pin to rise towards +12V, it would normally be dragged to 0.6V by the bias resistor to -12V a...