Sinclair micro TV

[mnfisher]

Thanks Steve,

That looks interesting. My attempts to get a DVD player signal to work - failed. It 'looks' like there is almost something at a few tuning points - but never quite resolves.

I found a small UHF transmitter on Aliexpress https://www.aliexpress.com/i/32983267665.html which might be worth a shot?

Also the Raspberry Pi has composite out - at least on earlier models ?

Martin

[chipfryer27]

Hi Steve / Martin

The pattern generator could be quite a useful thing to build. If restoring old devices it would be a good investment. I might actually have the Elektor issue in the loft somewhere.

Not having much background in TV, digital or analogue, would you not need to transmit away from the current digital channels in your area to stop the terrestrial signals interfering?

Regards

[mnfisher]

Started work on a Lissajous figure 'generator'.

It is possible (and probably easier) to generate the figures algorithmically - but I feel this needs to be 'analogue' (well almost).

Initially I tried using the DSP components wave generator (using v5 of the esp-idf tools - the timer interrupt fails - so downgraded to v4) - but rewrote using the DAC components for the ESP32 (output on A25 and for DAC2 A26) - and we could probably use the binaural beats generator too?

Still need to add 'varying' the frequency using a switch to alter - but here generating sine waves at 100 and 200Hz - we get our 'first' Lissajous figure

I'm using a 100 value lookup for the sine curve - alter hold1 or hold2 to alter the frequency... Might be useful to allow amplitude variation too?

Sine2.fcfx

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LabNation_Screenshot8.png (437.24 KiB) Viewed 9358 times

Martin

[chipfryer27]

Cooooool

I think your idea of the binaural beats generator would be less troublesome to code and generally much less effort.

Gen-1 fed to horizontal control
Gen-2 fed to vertical

So easy to vary as the modules are doing all the work for you. Actually, what about combining the two? Instead of flashing the LEDs at the frequency, visualise it. Could be quite a hypnotic experience.....

Regards

[mnfisher]

Just tested with the binaural beats ' machine'. The wave forms had become very 'noisy' and not nice
Removing the i2c OLED display fixed this - must be electrically noisy - possibly needs a smoothing cap?

With the display removed things resumed their harmonious state...

With OLED display (displaying stuff made it worse)

LabNation_Screenshot17.png (352.46 KiB) Viewed 9338 times

And with the display removed:

LabNation_Screenshot16.png (259.32 KiB) Viewed 9338 times

Martin

[chipfryer27]

Wow

That display is far noisier than I imagined. What model is it? Perhaps a clone of a brand?

My TRS-80 green screen would look quite cool displaying the waves but not sure if it's BASIC is up for the job and I've forgotten pretty much all of it's machine code. It's composite out so I should be able to get access to V/H bases somewhere.

Actually, I have a few monitors kicking around so I might just turn part of the evil lab into an evil gallery displaying Lissajous..... Of course I will need to fashion a helmet of sorts with flashy lights to accompany them. Perhaps measuring my skin resistance and using that as a time base? If it goes extra "wobbly" get out coz it means I'm annoyed or such like

Regards

[mnfisher]

Just a simple / cheap 32 x 128 i2c OLED (Banggood probably)

Z80 assembler - used to like that but it's been a long time. Some of my earliest programming was done on a TRS-80 in BASIC - a friend had one, and used to ring up and till him what to type I'm not sure we got much further than some Enigma 'solvers' - from the days when New Scientist was a great magazine. Went on to JJ Clessa in PCW (and Mike Mudge too - happy days!)

Go the full Hitchhikers - and don your jewelled battle shorts too, We are going to need photos!

Martin

[chipfryer27]

Halloween is coming soon, the only day I don't scare children and animals.....

Jewelled xyz-fronts..... could be on a winner

[mnfisher]

A (lack of) progress report.

Finally got a picture onscreen. Using a tiny 200mw UHF transmitter - I fiddled rather too much trying to get the esp32_composite_video_library to compile (it looks excellent - and I managed to add it as a component to a FC sketch - but some compilation errors remained ).
Then some fiddling trying to get some accurately timed pulses on esp32 with minor diversions into DAC_Continuous and gptimer (and v5.1 of the espressif tools). Everything seems to have changed and be deprecated in esp32 land- timer (now gptimer) RMT (tried that too) etc.

In the end - I gave up loaded a sketch in the Arduino ide and after a little fiddling there was an image I'd added a voltage divider to an esp32 and it didn't need it (composite video - 0.3v for black and 1v for white) see http://www.batsocks.co.uk/products/Other/TellyMate.htm - and I still think that B/W composite should be doable (the TellyMate uses an AVR 328p!

The picture is 'shifted' left and 'twiddling' the various adjustment pots would not get it further across the screen - and I'm not brave enough to go in with the soldering iron....

IMG_20231029_162515.jpg (181.88 KiB) Viewed 9216 times

And then - an animated gif!

IMG_20231029_163708.jpg (170.55 KiB) Viewed 9216 times

(It's a cat riding on the back of a giant space squid - or the right hand half thereof)

Martin

[mnfisher]

Remarkably the esp32 is outputting composite video in colour. Changing the setting to PAL (it was in NTSC) - improved things.

On the Sinclair and a pocket Casio - picture was 'ok' - B/W much clearer than colour. On a cheap '6in' Nikkai set - the picture (and colour) was better - but rolled vertically slowly (so timing slightly off)

TV wasn't as good in the olden days!

Martin