The Sinclair QL Forum

Good question.
I've collected quite a few retro computers and the Q.L. was one of the few Sinclair computers I have never owned so I since a lot of the computers I've collected are ones I could never afford when I was younger I finally got a Q.L.

Once I've got it reading microdrive tapes I'll have a mess around with the business software that came with it and then see about getting some games on it.

Hi,

I only have 1 QL PSU for 3 QLs, so I tried to buy another, I was shocked at the prices on eBay for a QL. Which I am not prepared to spend over £300 for a QL and PSU.

So I thought about a more update to date QL PSU, as mentioned earlier in the thread, there are designs available and the case could be reproduced by laser scanning the original case. Assuming no copyrights are in force.

I thought maybe the PSU plug connecting the QL would be hard, but is really just a 3 pin plug with a shaped key on top.

Would there be a market for this...

Most definitely there would be a market for a replacement PSU.

Don't worry about the design rights on the PSU case - they expired some tme ago, although you would need permission to put Sinclair on the case...

If a forum member would like me to take the design in this post from a theoretical design to a built and tested design, let me know.

Mark

1024MAK wrote:If a forum member would like me to take the design in this post from a theoretical design to a built and tested design, let me know.

Mark

Hi Mark,

Looks like you have done most of the hard work.

Do you think the case needs to look similiar to the old PSU, without the Sinclair branding.

I think this is an individual taste question. Myself, I'm not bothered about a replacement PSU looking like a Sinclair PSU, as the PSU normally lives out of site on the floor, or behind the monitor/TV.

When I built a replacement PSU for a Memotech MTX, because it is hard to get an off the shelf transformer with the required rating, I went for a larger transformer, so had to use a much larger case. This larger case allowed plenty of room inside to fit a IEC mains input connector (for a mains lead), the small strip board (that holds the rectifier diodes, smoothing capacitors and a fuse) and the DC-DC converter. The larger case also makes it easier for home construction.

Mark

Derek_Stewart wrote:

1024MAK wrote:If a forum member would like me to take the design in this post from a theoretical design to a built and tested design, let me know.

Mark

Hi Mark,

Looks like you have done most of the hard work.

Do you think the case needs to look similiar to the old PSU, without the Sinclair branding.

Personal taste would be for as small a PSU case as we could. While I appreciate some people would want it to look like a Sinclair one (as far as copyrights etc allow), I find the original Sinclair one too big and clumsy for my desk, it ends up gathering dust and being kicked on the floor out of the way.

Right, same here.

What definitely should look like the original is the QL-side plug - That's non-standard (At least I haven't seen one like that anywhere) and would probably be a 3D-print job - Contacts could be made from brass tubing pressed into the connector and soldered to the wires.

I guess most people wouldn't really accept anything that doesn't fit into an un-modified QL.

Tobias

If small is what is wanted, then we need to ditch a 50Hz iron cored transformer and use a mains switch mode power supply (SMPS) like this one. I strongly recommend buying from a normal retail outlet. Some of the mains SMPS available on line (from for example eBay) are cheap rubbish and do not comply with European or British safety requirements.

The output from the 9V DC PSU then needs to be fed into a small module (in a small box). This will convert the 9V DC into an AC output, which will then feed the 15V AC input.

But as I have not thought about the design of this module/circuit, let alone built or tested it, it will be a while before I post the details...

Mark

Can it have a blue LED too?