ℹ *EPISODE FAQ* • "Is your phototransistor the right part?" Let's just say maybe we'll _see the light_ and try some different options at the start of Part 2. Ad-free early access: patreon.com/perifractic • "The original frame rate was 50 fields per second interlaced not the 25 frames per second you have" That's true. It will serve us well to find the original tape in Thames TV's archives...
I saw you use an IR diode, you can see it because the diode is completely black, it’s actually not black but really deep red plastic, that is probably why it reacted on your phone light because that light is very bright, and some of the light passes through it. but the dark filter around that diode is to filter out normal light, It’s transparent in IR light
I'm betting it's the latter, the field rate. I have a feeling the lack of every other field might be to blame here, and was worried when I noticed a laptop was playing it to a CRT, not an original tape. Hopefully the tape can be found! I think this is very much the issue, but it's hard to know without knowing how fast that dot was supposedly flashing (if it was 50 strobes per second, or 25 strobes per second).
@@bopsop Ohh, good point! I didn't even realize it was an IR photo diode until you mentioned it being opaque. Yes, regular photo diodes do not have IR filters, and a CRT of course does not emit IR.
My father remembers this and built it, have shown him this, he said although you see a square it is actually a series of lines that transmit the data and you have used a IR diode not a photo transistor. It did work but as you show the time was totally impractical, but it was a fun and ground breaking idea at the time, he has still a number of BBCs and ZX spectrums. This has prompted him to think about looking at them again.
The golden age of home computing, where everything was new and when things did work you felt you'd actually achieved something...good to see it's still hard to achieve in the retro world so will make the completion so much sweeter !!
Wonder if anyone got that program working back in the day. hehe Imagine trying to tell the young'uns nowadays to do all techno techno-wizardry that just to grab a program off the TV... I mean TikTik. lol
Channel Four also transmitted software over audio during the morning Schools and Colleges block the day after 4 Computer Buffs went out, I remember sticking my cassette recorder next to the TV speaker and getting a demo of the Melbourne House Spectrum game "Mugsy" for my trouble.
I remember on the Dutch television after closing, they sent the software via the audio channels. You had to record it on a cassette and the next morning you had a new C64 program 🙂
@@RetroRecipesI completely understand. This current KR project of mine was my finest moment of “I can get this all wrapped up in two to three weeks” estimation errors. I’m excited to bring it to you, but it’s been tons of extra work- so I totally comprehend. (I’m looking at possibly two to three more weeks to finish up. Oh well. Quality matters!)
I know you probably already have the true answer, but i'm wondering if that's actually Photo Transistor 🤔to me it looks like an IR Photo Diode due to the color of the component.
Peri, i can say with confidence that outside of the orignal show producers/segment you are the ONLY person to ever attempt this. And if this program plays DOOM on a C64...
<a href="#" class="seekto" data-time="574">9:34</a> Phototransistors are a dime a dozen and function by changing resistance in response to light, which will then alter the base voltage of the transistor, giving an amplified square wave at the collector. They resemble miniature solar panels, and you could even use a small solar panel (from a garden variety charging garden lamp) if you can focus a light dot onto it. However, it looks like you've acquired an infrared light-emitting diode, which emits light rather than receiving it. To get the desired result, simply replace this component with a phototransistor, adjust the potentiometer, and use your oscilloscope to observe a nice square wave signal generated by the flashing light. On closer look it looks like you do have a phototransistor qsd-123ND designed to pickup infrared light. Buy one for normal white light and you should be good to go.
Yes, quite satisfying - when they actually ever worked. Most of the time, they were riddled with bugs/misprints and they never ran properly, if at all after hours of typing it all in and more hours de-bugging.
Not weird or surprising at all... The phototransistor you selected in an IR phototransistor... it has an opaque filter to visible light, that is why it looks black. The CRT is not an IR source so you will get nothing. You need a visible light phototransistor, or you might even be able to use an LED as an input source, perhaps a hi-eff red with a clear body. You'll need to experiment, just hook the LED to your O-scope and see if you can get it to respond.
A CRT is a great source of IR - anything which gives off heat is giving off IR. The issue however is that the IR phototransistor is not a drop in replacement for the regular (visible light) phototransistor - the thresholds between black/white will be extremely different and well beyond what can be compensated for using the schematic as shown. While it would be possible to get working with an IR phototransistor, the far better thing to do is to get a Light Dependent Resistor (LDR) which will perform the same functionality as a typical visible light phototransistor and is what are commonly used today. The schematic might still need some slight adjustments to cater for a different threshold, but it will be in a more realistic and practical range compared to an IR phototransistor and will make troubleshooting far easier - you'd be able to use a regular DMM to detect the difference between black/white from the resistor all by itself, the rest flow from there...
@@sirtra The signal is in the optical range, not IR, and the opaque optical filter was blocking out all visible light except IR, so that would have never worked even if the light was marginally triggering the sensor. I see that you responded to my comment twice and in that response I suggested a phototransistor FTP 100A that I used to make a light pen for my VIC-20 in the 1980's. It used the raster scan registers to detect the timing of the beam... I think I got the design from some magazine, but I built the pen and interfaced it to the DE9 pin Joystick/paddle connector (so long ago I can't recall how I did that.)
I love this stuff. My wife always shakes her head when i dump hours into getting this stuff to work (to never use it afterwards 😁). But it’s SO much fun to fiddle with it until it suddenly clicks and function, it’s just great. Many regards from Germany, as always! 👋😁
@@RetroRecipes I', 100% with you. As long as you're having fun, it's worthwile doing. My wife knows this and I think she likes seeing me tinkering, she always comes and takes a look and brings me something to drink. At least as long as I don't use the whole weekend for my projects, the kids are more important, obviously. Love your stuff, keep it up! I think your fanbase here in germany is growing with every video 😀
Haha i swear this is a fundamental difference between men and women, it even explains why many men refuse to ask for directions or where something is in a shop (much to the dismay of their partner) Sure, it might take me 10 times as long to find something the first time, but what i learn along the way will typically mean i'll know stuff i otherwise wouldn't and will be able to locate or find something entirely different far quicker in future. It all comes down to whether that future saving will offset the current penalty.. but as long as you're enjoying the ride then even the extra time invested isn't really wasted, it's a recreational activity!! 😁 If you have a baby in your arms though, getting directions is probably the better option... there are times when listening to the missus is advisable.
Takes me back to the days when my faithful Timex Datalink would read flashing data strips from a CRT... There was something magical about those sessions!
I don't remember seeing 4 Computer Buffs myself. I do remember that Ceefax (the BBC teletext service) broadcast programs over its pages - hidden in the "extra lines" of the TV broadcast signal. And going back even further there were games and programs transmitted by radio stations. I've been involved behind the scenes on this myself, so I'm looking forward to solving it and watching part 2...
Gosh, I envy you for your patience. I'd have had to go and lie down multiple times to cope with the frustration. 4 Computer Buffs was an excellent sister programme to Database on ITV. I remember people were invited to send titles for the programme made on their home computers. A wonderful Retro Recipe project. Compelling viewing as always. I hope the wallpapers I sent you will fit with the time travel theme for your own enjoyment. A fantastic job Perifractic.
@@RetroRecipes😂 Okay, I’d like to see the frustration bits now. My frustration edited bits look like Peter Capaldi smashing his fists into the TARDIS console. 💥😁😎
@@RetroRecipes Well, a good lie down can do wonders as Junifracttic demonstrates in your video. That or an extended period of shouting and swearing might help but could upset Babyfractic. So perhaps not.
Around this time, C4 also went through a phase of broadcasting software as an audio signal alongside the test card (test pattern for Americans) while they were off air during the day. This happened while I was at school, so I programmed my VCR to record it, then dubbed the audio to cassette and took it round to my friend's house (it was Spectrum software and I had an Atari 800). To our astonishment it actually worked, and the software turned out to be the full version of the game Pud Pud.
I laughed when I saw the guy demonstrate the various stages of the circuit being made. Reminded me of another TV show; "here's one I prepared earlier". Lost on your American viewers but loved by many back home.
Nooo, a cliff hanger at the end! Hopefully part 2 will also resolve the 39 year old cliff hanger from the TV show. A cliff hanger to resolve a cliff hanger. I can't take this! 😱😄
This series of videos is the reason I subscribed to Retro Recipes many years ago. The level of commitment to reach the end result is off the scale. More like this please!
This is probably the finest cliff hanger RU-vid episode, lol. The inner child in me has wondered for decades what that programme was. I was super excited that I was to finally find out. But no, you shot down my excitement like evil parents cancelling Christmas... I shall hit the refresh button every 5 minutes until part 2 arrives \o/
The "Videodat" system from the German "Computer Club" needed more expensive hardware, but it worked. The "Computer Club was very successfull, and after cancelation on WDR TV they continued as "CC2" on RU-vid. It was for over 25 years on real TV, and another 10 years online only. The software was transmitted in the beginning in "Basiccode 2", which made on compatible to almost any system. I don't remember if they still used Basicode 2 in the 1990s, as it was quite outdated then.
Thank you Perifractic and Puppyfractic a step back to when life seem less stressful. The excitement of getting a new program in your computer magazine and learning new skill like contacting your friends over the Bulletin Board and packet radio. Thanks you also saying hi to Ladyfractic & Babyfractic.
You could buy a whole teletext demodulator for a beeb, and there were special pages on late night bbc2? which were software. I actually did it a couple of times. It never worked for me, but I was in rural Cornwall at the time and the signal wasn't great. I have no idea why dad's girlfriend of the day had a beeb teletext unit but whatever. It was fun to play with.
4 Computer Buffs I recall being a decent computer show, I can also remember the software transmission thing but never built the gadget. Cool episode, thank you.
I really enjoy these retro-tech episodes, where you revive some cool aftermarket gizmo that wowed everyone at the time (me included!) I know this was a frustrating one for you, but I'm eagerly awaiting the conclusion. Even if it doesn't work I'll look forward to the next one.
Theres hidden scene in <a href="#" class="seekto" data-time="8">0:08</a> Microsoft Sidewinder Gamepad what i founded it Thanks to Retro Recipes. Microsoft are best since 1998-1999!
in the 70s I used to make things with LDRs even managed to send music over 6 inches with a bulb attached to a radio speaker and the LDR attached to the amp as the receiver. It was the good old days at the ripe old age of 13 lol.
Anyone home? First time watching. I really love the detail you put into your work! So many references and jokes many (including me!) might not get the first time!! And still having your old TV set and stuff, I mean, nobody puts a baby in a corner, right? ;-)
If you're just trying to get the program, which might be valuable for trying to see if you're actually getting your hardware to work, you could go directly to the video source and just sample the pixel color at that location on the screen as the signal, then you just need to sync when you sample the pixel and match it to the frame rate. Sample at least at Nyquist sampling rate, so 50 Hz I imagine for a BBC broadcast, then you can extract the actual signal directly, or you can use that to drive a transistor or SCR and send the signal to the C64 over the same pins as the loader program expects. Once you've got that, you can refine the original hardware receiver to get parity and match the expected output.
I was going to say "I've never heard of no '4 Computer Buffs'!" ... but if it was cancelled that quickly, it's no surprise. I'm going to have to see if I can find some episodes online. From the little clips you show here, it looks absolutely fan-tastic! I love how Channel 4 really tried hard to get the word "for" into as many of their program titles as they could manage. :) Cor... with the nasty scanned and compressed copy of PCW and the (probably) VHS recorded and horribly compressed original program... this REALLY is like archaeology.
No memory of this show, but do recall Database, an almost identical show that aired a year earlier on ITV, complete with the same hosts. Pretty much the only difference between the two, as far as I can tell, is the dot and hardware build. Database did transmit software, but only via audio. I used to video the show, and it took several hours, plus multiple blank audio tapes, before I was able to get a workable copy of a ZX81 program they'd sent.
This was beautiful! It reminded me of a project I'd built on the Atari ST for a wefax receiver. Wefax was an old method of delivering satellite images and you could use your ST to decode these images. IIRC, it was some sort of RLE encoding and a stop/end sequence.
Definitely a really cool idea, and very ahead of its time. However, I can definitely see why it didn't catch on as a popular data transmission method. Also, when you first explained the concept, and how nobody knows what the program really was, my first thought was "Man if you did that today and downloaded some mystery program off the TV, you'd either get some sort of ransomware, or get Rick Rolled." How times have changed!
just...such a weird feeling watching you open that box and pull out a disk... I guess nostalgia covers it, but it is so much more than that. I honestly miss the excitement of learning how to program on my 64... and dialing into BBSs in the middle of the night, finding new games, etc. Thanks for doing this stuff, Christian.
@RetroRecipes well, I have been a software engineer (professionally) for 25 years. I haven't felt that kind of excitement in a long time. I love what I do, for sure...but it will never be like Jr. High again!
Remember this very well. Was presented by Tony Bastable and Jane Ashton, with the legendary Guy Kewney. Sister show was called Database and ran for more than once season (I think).
Reminds me of a special message Isao Tomita recorded on his 1978 Bermuda Triangle album. You had to decode it using something called Tarbel...pretty damn obscure...
I remember this. I'm sure I tried to use my Spectrum with a light pen to download the program. My middle aged memory doesn't recall if I was successful. Great project this totally got my attention. Aaand you said you were 12, we're the same age !
FIIIINE. Take my sub. :) This is right up my alley. I was so involved with computers back in the day but cant stand programming in the traditional sense. The loops and hoops I built to short-step programming was, well, impressive for the time. Keep up the fine work!
Reminds me of a program I wrote for the BBC Model B which showed a form on the screen that you then printed out and sent in. It was written for the BBC Radio 4 programme I think called computer chip shop or something, around 1984 😊
Fantastic video! The whole process was absolutely mesmerizing and I loved the suspense that built up until the very end. It's a real shame that we couldn't see what was actually recorded. I’d love to try something like this and I can’t wait to see part two!
I miss my SX64. I mean, I miss the experiences of being able to spend endless hours writing software just for enjoyment and exploration. Now I just go to work, the work made possible by that background.
Gen-Z : Points phone at flashing dot... downloads emulator... runs software. Interesting video though. I think my dad recorded the Basicode transmissions waaaaay back, but for some reason the interpreter never worked properly on the ZX Spectrum.
Great video, but really nice touch with the many 1985 mentions and then when you are standing on a PCB you are wearing Nike Power Laces and the time stamp matched Doc Browns first experiment time and date at Lone Quick-Shot-Turbo Mall.
LGR did a video on the “Danmere Backer VHS Hard Drive Backup System” I wonder if broadcasting that signal would have allowed viewers to download data/programs. Same with Technology Connections video on Sony’s PCM-701 which did the same but with audio data.
How did I only just discover this channel??? Subscribed! Great video thank you for the time travel. I also love all your simple vfx. I even love how you left a little dirty chroma green at your feet. Legit retro.
I remember this when it was broadcast in the uk. I think at the time we had no home computer, or we had just got an amstrad cpc 464. So I was disappointed that I couldn’t try it myself. Looking forward to part 2
Brilliant work! I'm sure I remember this show, as I avidly watched any tech content in the 80s. Such a hilariously convoluted concept, I know you'll make it work somehow! So nice to see PCW magazine there too, I was a reader then with no idea I'd actually be writing for them seven years later!
At that time, we had a very similar TV programme in Germany that also occasionally did such kind of things. The WDR Computerclub. I think the programme ran until 2002 and one of the original presenters is still active on RU-vid today.
I just remembered that there was a device for the Amiga that could transfer floppies to VCR tapes. Video Backup System, I think it used less parts than this project. It seems to me that you should be able to isolate the flashing dot data straight from the video signal with the proper filter and timing. You could possibly also use a solar cell as the receiver. Apparently they can generate audio signals from light.
This video reminded me of one of the most coolest tech that I used to own as a kid. It was a ‘Wheel of Fortune’ game. It was just a simple blue box with a QWERTY keyboard and a multi line LCD display. The amazing part of this device is that it literally allows you to play along with real contestants on the actual gameshow when it airs at night. When you tune in to the nightly Wheel Of Fortune program and Pat Sajak has a puzzle in play, you’d point the toy at the TV screen and through the very analog scanlines in your CRT, the device would ‘download’ the puzzle, and at home, you’d be playing the exact puzzle that the contestants are playing through this device! The device wasn’t completely reliant on the TV show; it had hundreds of built in puzzles you can solve when you play with the device ‘offline’ As a kid, that absolutely astounded me.
Around similar time to this there was some programs transmitted as audio while BBC2 showed teletext around midnight. I recorded it, it was the game PudPud for the zx spectrum.
You must’ve excelled as a typing student, Peri. I didn’t realize as I learned how to type on a Commodore late in my single-digit years (the 80s) that it is something many people resist learning to do. It was interesting trying to explain to some people about ASDF and JKL;.
That was a really cool! I was born in '82 but, never got to experience the Commodore 64 (Or any of the other machines) until the late 90s. I was either using my old 386 or Tandy 1400. My friend did run a BBS so, I got to experience that and play some games which was nice. It seems like the UK had amazing computer tech shows going on, around that time! I know the US had something similar but, I doubt it had projects like what you were trying to build. Anyways, that was a great video!