Search found 122 matches
- Wed Sep 09, 2020 5:56 am
- Forum: WANTED
- Topic: Wanted : a ZX81 I/O board extension
- Replies: 6
- Views: 8941
Re: Wanted : a ZX81 I/O board extension
Great proposal to share the Gerber file I haven't yet ordered and built the v2 extension board. And I found an error with the v1 boards I've been using (flipped A and B side pins) These work fine as dev boards for prototyping. But, I need to fix it before I can use them to plug a card in. Once I've...
- Mon Sep 07, 2020 11:14 pm
- Forum: WANTED
- Topic: Wanted : a ZX81 I/O board extension
- Replies: 6
- Views: 8941
Re: Wanted : a ZX81 I/O board extension
Are you looking for old only (like the Maplin kits) or will new be okay also? Do you have specific interface needs? Are you looking for pre-made or is kit okay? I designed some quick extensions and can share the Gerber files if you want to order new PCBs. But you'd have to put then together yourself.
- Sun Sep 06, 2020 7:04 am
- Forum: Hardware
- Topic: This weekends projects
- Replies: 53
- Views: 32694
Re: This weekends projects
I finished assembly of the LM386 version
Works great. It's nice to have the reset switch for the SP0256-AL2.
And I can see the volume control being useful in some situations.
The Gerber files for both can be found here
https://github.com/mcarlson-sb/talk-again
Works great. It's nice to have the reset switch for the SP0256-AL2.
And I can see the volume control being useful in some situations.
The Gerber files for both can be found here
https://github.com/mcarlson-sb/talk-again
- Sat Sep 05, 2020 4:11 am
- Forum: ZX Spectrum Lounge
- Topic: It happened..
- Replies: 12
- Views: 11463
Re: It happened..
Okay. It turns out the keyboard membrane may just be bad. I removed the keyboard and used a jumper wire to "type" by connect between the two headers. Once I did this I got the inverted K and was even able to write a little program (PRINT 1 <ENTER>) So, I know the headers are good, the Z80 is good, t...
- Sat Sep 05, 2020 1:31 am
- Forum: ZX Spectrum Lounge
- Topic: It happened..
- Replies: 12
- Views: 11463
Re: It happened..
Sometimes I also get a black square then this
Typing at this point seems to do nothing.
So, I really am guessing memory. Typing at this point seems to do nothing.
- Sat Sep 05, 2020 1:10 am
- Forum: ZX Spectrum Lounge
- Topic: It happened..
- Replies: 12
- Views: 11463
Re: It happened..
I think I've got some memory issues - but I've got signal!
- Sat Sep 05, 2020 1:01 am
- Forum: ZX Spectrum Lounge
- Topic: It happened..
- Replies: 12
- Views: 11463
Re: It happened..
This is the signal going into the RF modulator Which (to my untrained eye) looks a bit like a video signal.
- Sat Sep 05, 2020 12:33 am
- Forum: ZX Spectrum Lounge
- Topic: It happened..
- Replies: 12
- Views: 11463
Re: It happened..
It looks like I got super lucky 4116 chips show +4.88v, - 5.17, 11.88 I'm getting a good 4mhz oscillation at the ULA TR 1 - base shows a signal TR 2 - base did not show a signal TR 2 - collector shows a signal TR 2 - emitter shows a signal I live in NTSC land. My TFT display auto detected a PAL sign...
- Fri Sep 04, 2020 11:39 pm
- Forum: ZX Spectrum Lounge
- Topic: It happened..
- Replies: 12
- Views: 11463
Re: It happened..
The quickest way to kill a ZX Spectrum, is to apply a DC voltage to the power input with the incorrect polarity, or apply a AC voltage. The correct polarity for the 2.1mm/5.5mm mini power connector is: inside is negative and the outside is positive. :shock: :shock: :shock: Pretty sure I got that ba...
- Fri Sep 04, 2020 4:57 pm
- Forum: ZX Spectrum Lounge
- Topic: It happened..
- Replies: 12
- Views: 11463
Re: It happened..
Issue 4S means it was made by Samsung I believe. It also means the keyboard membrane may even still be working! Some further info here http://blog.tynemouthsoftware.co.uk/2018/06/zx-spectrum-mystery-repair.html?m=1 Has it been recapped? Its unusual to be able to see all of the polarity and rating m...