Search found 519 matches
Re: LM7805 3A
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...
- Sun Jul 29, 2018 4:17 pm
- Forum: Hardware
- Topic: Video issue over rf. Changes with reset
- Replies: 7
- Views: 790
Re: Video issue over rf. Changes with reset
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...
- Sun Jul 01, 2018 10:54 am
- Forum: Software & Programming
- Topic: Unique original firmware from the Sinclair Archives
- Replies: 10
- Views: 1211
Re: Unique original firmware from the Sinclair Archives
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
Mark
- Sat Jun 30, 2018 10:29 pm
- Forum: Software & Programming
- Topic: Unique original firmware from the Sinclair Archives
- Replies: 10
- Views: 1211
Re: Unique original firmware from the Sinclair Archives
Where is that clapping emoji
Well done Urs
Mark

Well done Urs


Mark
- Wed Jun 13, 2018 3:04 pm
- Forum: The Off-Topic Section
- Topic: Today I Received...
- Replies: 23
- Views: 2595
Re: Today I Received...
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...
- Tue Jun 12, 2018 7:49 pm
- Forum: Hardware
- Topic: Q68 Order Process
- Replies: 116
- Views: 14454
Re: Q68 Order Process
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....
- Tue Jun 12, 2018 7:44 pm
- Forum: The Off-Topic Section
- Topic: Today I Received...
- Replies: 23
- Views: 2595
Re: Today I Received...
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
- Fri Jun 08, 2018 10:46 am
- Forum: The Off-Topic Section
- Topic: Today I Received...
- Replies: 23
- Views: 2595
Re: Today I Received...
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
- Fri Jun 08, 2018 10:41 am
- Forum: General QL Chat
- Topic: Hello? Anyone here?
- Replies: 8
- Views: 1043
Re: Hello? Anyone here?
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 was at an Acorn meet up.
There are full resolution 'photos (and the lower resolution 'photos) on my Flickr account here.
Mark
- Thu Jun 07, 2018 11:27 pm
- Forum: The Off-Topic Section
- Topic: Need electronic expert advice for a project
- Replies: 13
- Views: 1168
Re: Need electronic expert advice for a project
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...