Search found 679 matches

by 1024MAK
30 Apr 2021 12:55
Forum: NEW HARDWARE
Topic: Autofire Joystick project.
Replies: 5
Views: 155

Re: Autofire Joystick project.

Sounds like you’re have fun :D Smaller electro-mechanical relays are faster than larger ones. Beware that the ‘back EMF’ (a voltage spike) generated from the real coil when power is removed from it can damage semiconductor devices that drive it. A fast diode (1N4148 for small relays, UF4001 for larg...
by 1024MAK
29 Apr 2021 15:38
Forum: NEW HARDWARE
Topic: Autofire Joystick project.
Replies: 5
Views: 155

Re: Autofire Joystick project.

There are chips that can be used, for example CD4016BE or CD4066BE analogue switches. CD4016BE datasheet from TI CD4066BE datasheet from TI Use the output of the NE555 (or 7555 or TLC555CP) to feed one of the control inputs on one of the switches/channels of the CD4016BE or CD4066BE chips. Then conn...
by 1024MAK
29 Apr 2021 13:14
Forum: NEW HARDWARE
Topic: Autofire Joystick project.
Replies: 5
Views: 155

Re: Autofire Joystick project.

The problem with the joystick ports on the MTX is that they are part of the keyboard matrix. The keyboard matrix does not use a 0V common but is instead a grid where the system controls the voltage on one set of lines (outputs) while monitoring the logic level on the other set of lines (inputs). By ...
by 1024MAK
23 Apr 2021 17:20
Forum: GENERAL DISCUSSIONS
Topic: Eye-watering ebay prices
Replies: 38
Views: 1236

Re: Eye-watering ebay prices

Actually, Claus, you and Dave it seems, have the lions-share of Memotech hardware between all the forums members (honourable mentions to Andy, Martin, Bill and maybe Tony?) but I've always wondered, aren't you guys bidding on auctions against each other? :lol: Err, have you seen the survey results ...
by 1024MAK
20 Apr 2021 19:34
Forum: GENERAL DISCUSSIONS
Topic: Eye-watering ebay prices
Replies: 38
Views: 1236

Re: Eye-watering ebay prices

That's interesting Jon. So he is selling up because he's exiting, in this case, the Memotech "scene"? Not exactly, no. He is happy to sell items if there is someone who is willing to pay the price he wants. I’m not sure he’s exiting, as that would mean he was ‘in’ the ‘scene’. He does this with a w...
by 1024MAK
19 Apr 2021 19:28
Forum: HARDWARE
Topic: Edge connector woes
Replies: 8
Views: 453

Re: Edge connector woes

That does not look too bad. A bit of desoldering and some new solder and it will be like new.

Mark
by 1024MAK
18 Apr 2021 16:39
Forum: HARDWARE
Topic: Edge connector woes
Replies: 8
Views: 453

Re: Edge connector woes

The technique to refresh edge connectors on other machines is to put on lots of flux and then a reasonable amount of solder on each finger and make sure that the new solder covers the whole thing, then use desoldering braid to suck off the excess solder, pulling the braid with soldering iron on top...
by 1024MAK
18 Apr 2021 14:41
Forum: HARDWARE
Topic: Take care when remove ics (Saved a VDP)
Replies: 6
Views: 467

Re: Take care when remove ics (Saved a VDP)

Unfortunately the metal used for the pins on some chips corrodes and weakens over time. Obviously this only becomes a problem if the unit is stored in less favourable conditions.

Mark
by 1024MAK
16 Apr 2021 13:23
Forum: GENERAL DISCUSSIONS
Topic: Eye-watering ebay prices
Replies: 38
Views: 1236

Re: Eye-watering ebay prices

This eBay seller is well known for their way of trading. They always list items at well above the market rate, and keep re-listing month after month.

Mark
by 1024MAK
14 Apr 2021 03:33
Forum: GENERAL DISCUSSIONS
Topic: Best dust cover
Replies: 6
Views: 425

Re: Best dust cover

I don’t know about now, but some years ago there was a guy that would make custom sized dust covers. Some on the World of Spectrum forums asked for dust covers for the ZX Spectrum +3. I jumped on the same bandwagon ;) If you search the U.K. eBay site for “dust cover zx spectrum” you will find simila...