Search found 2264 matches
- Wed Apr 18, 2018 4:38 pm
- Forum: SALES
- Topic: ZX8-KDLX - replacement keyboard for ZX81 with SMD switches
- Replies: 6
- Views: 12794
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...
- Sun Apr 01, 2018 3:49 pm
- Forum: Development
- Topic: Sketchy - An online screen designer
- Replies: 11
- Views: 7467
- Sun Apr 01, 2018 3:31 pm
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 135796
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 ...
- Sun Apr 01, 2018 3:26 pm
- Forum: Development
- Topic: If you like your submarine simulations fast, arcadey,...
- Replies: 46
- Views: 24179
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.
I can not see much from these pics, sorry. Just a white line in between.
- Wed Mar 28, 2018 10:42 pm
- Forum: Development
- Topic: ZX Printer Belt
- Replies: 139
- Views: 91931
Re: ZX Printer Belt
Wow ! good work !
- Sat Mar 24, 2018 10:41 pm
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 135796
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.
- Fri Mar 23, 2018 12:43 pm
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 135796
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.
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.
- Fri Mar 23, 2018 1:42 am
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 135796
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 ...
- Thu Mar 22, 2018 10:57 pm
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 135796
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.
- Thu Mar 22, 2018 12:40 pm
- Forum: Development
- Topic: ZX81 ULA-in-a-CPLD
- Replies: 238
- Views: 135796
Re: ZX81 ULA-in-a-CPLD
In my case I create +3.3V for the CPLD from the Zeddy +5V rail using LM11117-3.3V plus 4 capacitors (100nF & low ESR 10uF) at both sides (in & out). As in Sinclair's philosophy I don't waste money for voltage regulators not needed. There is already a voltage regulator for 5V that's enough. All you ...