ZX-Wespi tape loading

Discussions about Sinclair ZX80 and ZX81 Hardware
Lardo Boffin
Posts: 1805
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX-Wespi tape loading

Post by Lardo Boffin »

A bit neater.

38886F99-7DD4-4364-9329-75C361372F8B.jpeg
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Lardo Boffin
Posts: 1805
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX-Wespi tape loading

Post by Lardo Boffin »

The Wespi switches on and off nicely now. When it is off there is no interference on the screen.

But it still won’t load from tape! Argh. I have used known good equipment and it won’t load anything. As soon as I get the volume right it drops out to a white screen, either with or without the K, from the loading screen.

Just to make sure the zeddy is still ok I will completely disconnect the Wespi and try tape loading again.

Could the extra wiring be having an effect on the signal even when the Wespi is off?
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Lardo Boffin
Posts: 1805
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX-Wespi tape loading

Post by Lardo Boffin »

Loads fine with the wires disconnected.

So, either I add another switch for the tape in / out lines or give up on tape loading with the Wespi. I guess the latter for now.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Moggy
Posts: 2810
Joined: Wed Jun 18, 2008 2:00 pm

Re: ZX-Wespi tape loading

Post by Moggy »

No idea how yon device works Lardo, but it is good practice when using audio signals that any signal carrier wire is either of the shielded type or at worst a twisted pair with the ground/earth wire as the zeddy is a bit bit noisy electronically speaking.
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1024MAK
Posts: 4257
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: ZX-Wespi tape loading

Post by 1024MAK »

The 100Ω resistor and the internal protection diodes in the chip on the module are likely affecting the voltage levels that the Zeddy ULA (or equivalent) sees on its Ear input. The protection diodes may flatten and distort the signal. The Ear signal to/from the module will therefore have to be switched.

Also, strange effects will occur if a module like the one used for the ZX-Wespi is used with it’s +5V disconnected only, or sometimes even with both the +5V and the 0V/GND lines disconnected. This is due to back feeds (the device attempting to steal power from the device, that is the Zeddy, via the protection diodes) from the input/output connections.

Normally I would recommend leaving the +5V and the 0V/GND lines connected and instead switch both the input and output wires. Note that I have not tried this.

Mark
Lardo Boffin
Posts: 1805
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX-Wespi tape loading

Post by Lardo Boffin »

Cheers both.

It never crossed my mind to switch off the non-voltage lines! Will try that on the next one. :D
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Lardo Boffin
Posts: 1805
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX-Wespi tape loading

Post by Lardo Boffin »

It lives!

4DE33991-750B-4000-B195-5BE47DBB4593.jpeg

(Usual caveat that the wiring needs to be tidied up!).

By switching the audio lines rather than the power lines I can alternate between Wespi and cassette player quite easily.

Its not exactly practical in my Tatung 81 as it has a lid and the cassette cables plug into the motherboard inside - the Wespi won’t load if the Ear cable is plugged in. But for how often I load from tape its not an issue. They key thing is that a normal zeddy has the Ear socket on the outside so it would be easy to switch off the Wespi and plug in a cassette cable to load from tape and them reverse the process to go back to the Wespi. Although I seem to have to reboot the zeddy in order for this to work.

Thanks again Mark!
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
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