Search found 1257 matches

by mrtinb
Mon May 09, 2016 8:55 pm
Forum: Hardware
Topic: Hi-res graphics mode in the ZX81
Replies: 13
Views: 6361

Re: Hi-res graphics mode in the ZX81

There are several methods of hires. Most common is to create a screen somewhere in memory which is displayed with your own hiresdisplayroutine. There are also hardware interfaces which give you place in memory where you can built UDG and use them as normal characters. If I understand correctly - Tr...
by mrtinb
Sun May 08, 2016 6:41 pm
Forum: Hardware
Topic: MIC amplifier
Replies: 71
Views: 14085

Re: MIC amplifier

mahjongg wrote:you can try implementing the mic pre-amplifier I've built into my ZX81 clone, which is working well.
So the ZX81 connected to the left, and the tape to the right?
by mrtinb
Sun May 08, 2016 6:37 pm
Forum: Hardware
Topic: Creating Wilf Rigter's ZXKBD v3
Replies: 52
Views: 14261

Re: Creating Wilf Rigter's ZXKBD v3

Wow!

My keyboard pcb works. The pcb is not connected to the keys yet, but when I shortcut the wires, corresponding letters show on the screen. Yes! My first electronics project works!

What is left now is to connect the three pcbs with the keys.
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by mrtinb
Fri May 06, 2016 7:40 pm
Forum: Hardware
Topic: Hi-res graphics mode in the ZX81
Replies: 13
Views: 6361

Re: Hi-res graphics mode in the ZX81

Hi :-) There are many different ways for Hi-res on ZX81, and here are some articles to read about the possibilities: http://www.user.dccnet.com/wrigter/index_files/ZX%20Video%20Tutorial.htm http://www.user.dccnet.com/wrigter/index_files/1khires.htm http://www.fruitcake.plus.com/Sinclair/ZX81/Softwar...
by mrtinb
Wed May 04, 2016 10:56 pm
Forum: Hardware
Topic: MIC amplifier
Replies: 71
Views: 14085

Re: MIC amplifier

Moggy wrote:Thought to honest such pre-amps are now so inexpensive to buy ready made it's not worth building yourself.
Like this one? TDA1308 Headphones amplifier board For the Power amplifier Pre-amp amplification use
by mrtinb
Wed May 04, 2016 8:04 am
Forum: SALES
Topic: More ZXpands Available Now
Replies: 96
Views: 25273

Re: More ZXpands Available Now

Since I can't seem to get loading from MP3-player to work on my ZX81 anymore, I think I will need to look into getting a ZXpand perhaps! Will there be a new batch made anytime? I have the same problem. I have two approaches. Amplifying MIC signal Looking forward to buy the ZXblast in a few weeks
by mrtinb
Tue May 03, 2016 11:35 am
Forum: Hardware
Topic: MIC amplifier
Replies: 71
Views: 14085

Re: MIC amplifier

I assumed a earphone could be replaced by a mini jack. It might not be so.
by mrtinb
Tue May 03, 2016 10:22 am
Forum: Hardware
Topic: MIC amplifier
Replies: 71
Views: 14085

Re: MIC amplifier

I was thinking about building this little circuit between ZX81 and iPhone, because the signal is too low for the iPhone to record. I'm not sure about the components' values. And I should probably find a newer cheaper plastic version of the capacitor (which did not exist at the time the diagram was m...
by mrtinb
Tue May 03, 2016 5:46 am
Forum: Hardware
Topic: MIC amplifier
Replies: 71
Views: 14085

Re: MIC amplifier

Um, how does the +5V get to the transistors collector load resistor? Speaking of which, where is the collector load resistor? I would expect the +5V to go to the collector load resistor, then the other end of this resistor to go to the transistor collector terminal / junction with the base bias res...
by mrtinb
Mon May 02, 2016 10:24 pm
Forum: Hardware
Topic: MIC amplifier
Replies: 71
Views: 14085

MIC amplifier

I'm having trouble reading the MIC-signal to save from my ZX81. Problem converting WAVE Problem saving files from Toddy Forth I found a schematic in an old electronics book on how to amplify a signal with a transistor. Maybe I could make a little PCB with two mini jacks and this little circuit to be...