Improving Timex/Sinclair Tape Loading

Discussions about Sinclair ZX80 and ZX81 Hardware
Lardo Boffin
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Joined: Sat Nov 26, 2016 1:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Mon Oct 09, 2017 9:05 am

TMAOne wrote:
Sat Oct 07, 2017 7:54 am
I'm gratified that my little "tape cleanup box" may have a litter of cousins soon.
And it only took us 4 years!
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

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sirmorris
Posts: 2667
Joined: Thu May 08, 2008 4:45 pm
Location: oxon, uk

Re: Improving Timex/Sinclair Tape Loading

Post by sirmorris » Mon Oct 09, 2017 9:06 am

The GND connection may not be fully connected in your net. It should probably continue to the negative terminal battery. Eagle complains when power rails aren't explicitly named. I don't know about kicad. The pins 11 & 4 on IC1 might be nominated as power and therefore should only connect to suitably named nets.

I think the original schematic leaves certain details to be assumed. It's for engineers/hobbyists, not computers. The power connections would be implicitly considered.
--=== ZXpand+ ... A more moderner all-in-one upgrade solution for ZX81 ===--
* SD/MMC storage * 32K Hires-capable RAM * AY sound chip * Joystick port * Serial *
* BASIC enhancements - plug & play * Reset button * Auto-boot facility *

Lardo Boffin
Posts: 626
Joined: Sat Nov 26, 2016 1:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Mon Oct 09, 2017 9:09 am

Parts list so far:-

Item.......Link.................................................................................Price.......Qty
C1 to C4 http://cpc.farnell.com/multicomp/mcrr25 ... dp/CA06295 £0.9 For 5
C5 http://cpc.farnell.com/multicomp/mcfyu6 ... dp/CA05016 £0.37 For 10
C6 http://cpc.farnell.com/cornell-dubilier ... dp/CA05876 £1.21 Each
D1 http://cpc.farnell.com/unbranded/1n4148 ... dp/SC07296 £0.47 For 50
IC1 http://cpc.farnell.com/texas-instrument ... dp/SC13781 £0.85 Each
LED1 http://cpc.farnell.com/kingbright/l-483 ... st=Sc11591 £0.72 For 10
S1 http://cpc.farnell.com/unbranded/slide- ... dp/SW03207 £2.11 For 10


Will add the resistors shortly.

If anyone wants to validate this lot that would be appreciated.

Edited to include the LED specification.
Last edited by Lardo Boffin on Mon Oct 09, 2017 2:04 pm, edited 1 time in total.
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

User avatar
sirmorris
Posts: 2667
Joined: Thu May 08, 2008 4:45 pm
Location: oxon, uk

Re: Improving Timex/Sinclair Tape Loading

Post by sirmorris » Mon Oct 09, 2017 10:04 am

I normally don't fret about the LED. Pick a nice colour. I like pink! You can change the current limiting later. It may be that the LED is meant to show a valid signal and in this case the current rating may be critical. So go for a bog standard red led, with an iF of about 20mA. If it proves tricky the current limiting can be trimmed with another resistor if necessary.
--=== ZXpand+ ... A more moderner all-in-one upgrade solution for ZX81 ===--
* SD/MMC storage * 32K Hires-capable RAM * AY sound chip * Joystick port * Serial *
* BASIC enhancements - plug & play * Reset button * Auto-boot facility *

Lardo Boffin
Posts: 626
Joined: Sat Nov 26, 2016 1:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Mon Oct 09, 2017 10:34 am

sirmorris wrote:
Mon Oct 09, 2017 10:04 am
I normally don't fret about the LED. Pick a nice colour. I like pink! You can change the current limiting later. It may be that the LED is meant to show a valid signal and in this case the current rating may be critical. So go for a bog standard red led, with an iF of about 20mA. If it proves tricky the current limiting can be trimmed with another resistor if necessary.
Thanks. Pink sounds good.

Judging by the instructions the LED is supposed to light up when the desired input volume is reached so I suspect it needs to be just so!
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

User avatar
sirmorris
Posts: 2667
Joined: Thu May 08, 2008 4:45 pm
Location: oxon, uk

Re: Improving Timex/Sinclair Tape Loading

Post by sirmorris » Mon Oct 09, 2017 11:56 am

"However, when pulses appear at the output of IClB, the cathode of D2 is brought low. This causes the output of IC I C to go low and allows current to flow through the LED, thus causing it to glow."

So the led is either on or off, it's not an active component. Feel free to relax.
--=== ZXpand+ ... A more moderner all-in-one upgrade solution for ZX81 ===--
* SD/MMC storage * 32K Hires-capable RAM * AY sound chip * Joystick port * Serial *
* BASIC enhancements - plug & play * Reset button * Auto-boot facility *

Lardo Boffin
Posts: 626
Joined: Sat Nov 26, 2016 1:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Mon Oct 09, 2017 12:06 pm

Excellent! Any recommendations (ideally from CPC like the rest of it)? No real idea about these things... :oops:
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

User avatar
sirmorris
Posts: 2667
Joined: Thu May 08, 2008 4:45 pm
Location: oxon, uk

Re: Improving Timex/Sinclair Tape Loading

Post by sirmorris » Mon Oct 09, 2017 12:44 pm

Standard red led. forward voltage ~ 2-3v, forward current 10-30ma. Really there's no hard criteria here.
--=== ZXpand+ ... A more moderner all-in-one upgrade solution for ZX81 ===--
* SD/MMC storage * 32K Hires-capable RAM * AY sound chip * Joystick port * Serial *
* BASIC enhancements - plug & play * Reset button * Auto-boot facility *

Lardo Boffin
Posts: 626
Joined: Sat Nov 26, 2016 1:42 am

Re: Improving Timex/Sinclair Tape Loading

Post by Lardo Boffin » Mon Oct 09, 2017 2:05 pm

Thanks. Have added one that is middle of the road.
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

User avatar
TMAOne
Posts: 119
Joined: Thu Aug 16, 2012 5:56 pm
Location: Waterloo, Ontario, Canada

Re: Improving Timex/Sinclair Tape Loading

Post by TMAOne » Mon Oct 09, 2017 2:22 pm

sirmorris wrote:
Mon Oct 09, 2017 12:44 pm
Standard red led. forward voltage ~ 2-3v, forward current 10-30ma. Really there's no hard criteria here.
Yes anything you can scrounge should do just fine. It's like the black & white stripes--it's just visual feedback, and you get "a feel" for what volume setting works best after a couple of LOADs.

Is the layout from the .pdf really unusable? I took a screen grab and it looks square to me. Heck I drew mine by hand and it works. :lol:

Image
Attachments
Improving ZX81 Loading.pdf - Adobe Acrobat Reader DC_2017-10-09_08-11-58.jpg
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