Understanding ZX81 signals to Timex/Sinclair Printers

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1024MAK
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Re: Understanding ZX81 signals to Timex/Sinclair Printers

Post by 1024MAK »

Can you please either upload the schematic as a non lossy compressed image format (e.g. PNG) that is not too big (dimensions) or too large (file size) or alternatively zip the file, then upload the zip.

The reason being that the forum automatically compresses jpg images to reduce their file size, but this wreaks schematic diagrams :(

Mark
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XavSnap
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Re: Understanding ZX81 signals to Timex/Sinclair Printers

Post by XavSnap »

Image



Old one : (R6 resistor ok)
Image
Last edited by XavSnap on Fri Mar 06, 2020 9:11 pm, edited 1 time in total.
Xavier
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1024MAK
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Re: Understanding ZX81 signals to Timex/Sinclair Printers

Post by 1024MAK »

I would also expect the diode D2 to connect to the +9V (+10V) rail rather than to the motor. Most small DC motors only have two electrical connections. I would expect D2 to have been provided to clamp the “back” or “reverse” EMF generated by the motor.

This is normally done by wiring a diode (reverse biased) across the motor connections. Which here are positive to the +9V (+10V) rail, and negative to transistor TR6 collector.

Mark
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XavSnap
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Re: Understanding ZX81 signals to Timex/Sinclair Printers

Post by XavSnap »

Thanks Mark,
I had to remove a polarized capacitor too… and change the voltage converter (too big).
ZxPrinter_redraw.jpg
Capture2.JPG
Xavier
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XavSnap
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Re: Understanding ZX81 signals to Timex/Sinclair Printers

Post by XavSnap »

Hi,
I try to find out how the paper feed works. is there any system to gear the rotation of the paper feed roller?
:shock:
ZX Printer_meca.jpg
Xavier
Rafael
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Alphacom 32

Post by Rafael »

I connected an ALPHACOM 32 to a IBM THINKPAD 760ED, Centronics port, jun 2002.
Turbo C 2, DOS.
All information available. I Don't know if it's útil.
Rafael, Bogotá, Colombia.
P.S. Excuse my poor English, pls.
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