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Re: Fuller FD42 Keyboard

Posted: Sat Jan 19, 2019 10:46 pm
by gammaray
I believe if you are going to use a barrel connector put a RECTIFIER in between the power and switch. That way a reversed polarity power transformer will still have the same polarity to the ZX81. And you wont have to remember which power supply goes with which computer.

I would like to add that to the Spectrum but going to have to work on how to integrate into available space.

CORRECTION I am awake now...
RECTIFIER.jpg
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Re: Fuller FD42 Keyboard

Posted: Sun Jan 20, 2019 1:27 am
by 1024MAK
For simple reverse polarity protection, a 1N400x diode will do (where 1N400x means any from the 1N4001 to 1N4007 series).

So that any 9V PSU, of either polarity will work, you need a bridge rectifier. Either a ready made one, or four 1N400x diodes connected up correctly.

Rubber key ZX Spectrums are tricky due to the limited space inside the case. Later models are rather easier if you don’t mind using a chassis socket and drilling a new hole in the case.

However, if you use expansions or it is a 128k or a +2 (grey), you will need diodes / bridge rectifier rated at 1.5A (48k/+) or 3A (128k / +2) or greater.

Mark

Re: Fuller FD42 Keyboard

Posted: Sun Jan 20, 2019 1:45 pm
by Tezz
Thanks guys that's great. I'm glad that there's a simple SD extension I can add without modifying the Zxpand+. I'll definately add the 1N400x diode. With the barrel jack socket and rocker switch installed on the back of the Fuller case I was then going to hardwire the board directly from the switch making sure to wire it with the correct polarity based on which PSU I bought but with the diode inbetween I can simply wire it either way.

I drilled the holes in the Fuller case yesterday and was able to place the ZX81 board in the correct position and then carefully placed the paper extension template also in its correct position. The clearance looks about right now for the expansion slot comparing it with the photo of the real thing.
correct_extension_placement.png

Re: Fuller FD42 Keyboard

Posted: Mon Jan 21, 2019 12:21 pm
by mrtinb
I think you'll enjoy this keyboard. From what I've read in these forums, it's the keyboard to run for.

Re: Fuller FD42 Keyboard

Posted: Mon Jan 21, 2019 1:17 pm
by Tezz
I Googled bridge rectifiers yesterday and read up a little regarding the diode bridge. Thanks for that info. I will go for the four 1N400x diodes as you've suggested Mark.
mrtinb wrote:
Mon Jan 21, 2019 12:21 pm
I think you'll enjoy this keyboard. From what I've read in these forums, it's the keyboard to run for.
Thanks, I'm looking forward to having the Fuller setup.

Re: Fuller FD42 Keyboard

Posted: Fri Feb 08, 2019 12:52 pm
by Tezz
Well I'm back to square one with the edge connectors, whilst I was waiting for Pokemon to return Paul contacted me directly by email saying he had some he could sell to me so a friend of mine sent a payment via PayPal to Paul as I don't use PayPal personally and I've heard nothing back since. It's been a few weeks and Paul hasn't replied to my emails or messages on here asking what's happening with them. I guess I will have to write that off and see if Pokemon is back. Very disappointing.

Re: Fuller FD42 Keyboard

Posted: Fri Feb 08, 2019 1:34 pm
by mrtinb
Or maybe you give it some time. People here are very helpful. But since this is sparetime hobby, help here is secondary to other chores like daytime work.

Re: Fuller FD42 Keyboard

Posted: Fri Feb 08, 2019 1:48 pm
by Tezz
mrtinb wrote:
Fri Feb 08, 2019 1:34 pm
Or maybe you give it some time. People here are very helpful. But since this is sparetime hobby, help here is secondary to other chores like daytime work.
Yes, that's basically what I said in my message to Paul that he's probably not had time to send them yet but I'd expect a reply a least to let me know what's happening, he's been online here.