Search found 2225 matches

by PokeMon
Tue May 08, 2018 12:23 am
Forum: SALES
Topic: ZX81CCP
Replies: 102
Views: 13560

Re: ZX81CCP

ZX8-CCB is temporarily sold out but planned to be come back in a few weeks. ;)
by PokeMon
Wed Apr 18, 2018 4:38 pm
Forum: SALES
Topic: ZX8-KDLX - replacement keyboard for ZX81 with SMD switches
Replies: 5
Views: 1156

Re: ZX8-KDLX - replacement keyboard for ZX81 with SMD switches

The ZX81 keyboards with tactile switches as replacement for membranes is back now after 6 weeks sold out. There is only the completed/assembled version available but with lower price (same now as previous kit price). So assembly kits and pcb only are no more available as all boards have been assembl...
by PokeMon
Sun Apr 01, 2018 3:49 pm
Forum: Development
Topic: Sketchy - An online screen designer
Replies: 11
Views: 723

Re: Sketchy - An online screen designer

Cool ! 8-)
by PokeMon
Sun Apr 01, 2018 3:31 pm
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 198
Views: 20757

Re: ZX81 ULA-in-a-CPLD

Not sure where you measure but can be a ground problem at the end. What is the signal when you take it directly with GND and VID on your small board (as close as possible) ? I wouldn't take the signal from the modulator or feed it through as this can give more problems. Where do you get your signal ...
by PokeMon
Sun Apr 01, 2018 3:26 pm
Forum: Development
Topic: If you like your submarine simulations fast, arcadey,...
Replies: 46
Views: 3026

Re: If you like your submarine simulations fast, arcadey,...

Maybe possible to post a better resolution picture here with the normal screen (how it should be) and what is different with ZX8-CCB.
I can not see much from these pics, sorry. Just a white line in between.
by PokeMon
Wed Mar 28, 2018 10:42 pm
Forum: Development
Topic: ZX Printer Belt
Replies: 102
Views: 8891

Re: ZX Printer Belt

Wow ! good work ! 8-)
by PokeMon
Sat Mar 24, 2018 10:41 pm
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 198
Views: 20757

Re: ZX81 ULA-in-a-CPLD

Yes I like these "little logic" gate series. The LVC (low voltage cmos) are fast and powerful. No need for transistors.
by PokeMon
Fri Mar 23, 2018 12:43 pm
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 198
Views: 20757

Re: ZX81 ULA-in-a-CPLD

By the way - I changed R5 to 150R long time ago, didn't update the schematics.
R6 stays still 390R.
Together with 75R load gives about 1Vpp Video at the output.
No need for any decoupling capacitors or short circuit protection.
by PokeMon
Fri Mar 23, 2018 1:42 am
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 198
Views: 20757

Re: ZX81 ULA-in-a-CPLD

maybe i use a sot-23 dual inverter / buffer that will do same job but save on pcb space. Yes - that's the best. Get your digital video and sync to these and mix together after. Take this sot 23-6 device 74LVC1G14 for example. https://assets.nexperia.com/documents/data-sheet/74LVC2G14.pdf Maybe you ...
by PokeMon
Thu Mar 22, 2018 10:57 pm
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 198
Views: 20757

Re: ZX81 ULA-in-a-CPLD

Be aware how you realize the transistor amp. If this is just an emitter follower, than the shit comes out of the CPLD already. Anything you do at the 5V or second video power supply rail will have no effect. ;)