More years ago than I would care to admit (OK it was 1970) When I was stationed on Vietnam, we used an encryption device on our FM radio sets to communicate between our patrol s who used the PRC77 (a PRC25 unit modified to use encryption) and the tactical communications bunker, where I worked. If you tried to monitor the transmissions without the crypto unit engaged, it sounded a bit like your device, however much faster. I recall setting the "patch" devices for those crypto units which were heavy as hell for the poor Radio Telephone operators, it was a sort of pin adjustable set of slides that had to all be set according to the code that changed daily. So at midnight, the dude on the night shift would have to open the safe, remove the little code square from a book, then change the code pancake device which set the pin lengths as one of 24 lengths if I recall, then the device was inserted into the plug receptacle and the lever was pushed which protruded the pins to the proper code location and t he radios could then communicate in the secure mode. A similar device was used for teletype, however in that case each device had to have its own patch set at midnight. If one pin was not set correctly on the TTYP's then no commo was possible. This was a rare occurrence but did indeed happen from time to time.The ttyps each had a crypto device that had a block with 36 wires and 37 areas that wires could be inserted. They were sort of like the DuPont type connector but had a lock ring that kept the pins in their plugs then the patch would be inserted in this huge gray box and the door closed, key removed and the unit could be put to work.
Jerry Ericsson I was born one year later, 1971, and 19 years later we were still using the prc77 in the Marine Corps duing the Gulf War. There was an encryption device that was changed daily by a com guy with a key worn around their necks. I was on a M60A1 tank with vietnam issue radios that also used the same encrytion. Whenever the comm guy came to change the freq we were ordered off the tank and were not allowed to see what he was doing. Every other branch of service had singuar (sp?) frequency hopping radios, with a few exceptions. We still had the prc77s for several years after the Gulf War, in our Humvees and Trucks.Great story and Welcome Home sir.👍
What did I do today? Took a sick cat to the vet. Then I fixed a B3603 module that had shorted it's buck diode. Then I hooked that module up to a bucket for electrolysis to do rust removal. Now I'm watching you!
erik satie's gymnopedies no. 3! absolutely gorgeous if somewhat tonally incongruous (or maybe cognitively dissonant) piece! take that mom, I was paying attention in music history!
You made me happy to find your comment. I could recognize song from the first chords (as it's one of my favorites), and wanted someone else to have spotted it too, haha
The most intelligible part of speech lies between 500 to 3kHZ. So a few bands doesn't quite cut it in terms of representing your source. Such an awesome project. Keep going and I think you'll be pleasantly surprised!
When you reconnect the first channel, you can hear that it does not only outputs your carrier: it sounds more like a ring modulated version of it, so maybe the control voltage varies too fast: Try to smooth it out with a lpf, or increase the time const past the peak detector ... Or both
Actually today I have spent an hour or so disassembling some inside house telephone wire. I found that there were 5 pair of relatively thin solid strand copper wire inside, much thiner then I recall from my days in the US Army, back then we used a much heavier wire and there were only 4 colors of wire inside instead of 6. I was a bit disappointed but I guess things change over time, and I noticed the wire was marked "MADE IN CHINA" so it must be a much newer sort of wire. I had been using it as an easy way to channel my hifi all over the house, as I found a large spool of this wire beside the highway back in the late 1990's, it appeared to have fallen off the back of a repair truck, and there was probably about 50 feet of the stuff left on the end of the real. Well wireless technology has pretty much put an end to my attempt to channel music all over the house, and in fact nobody in the house even listens to the big stereo anymore, don't think it has been turned on in over 5 years. Sad to as it has a wonderful sound with the 16 inch bass woofers and a nice set of SONY speakers to give life to the music, through a very large amplifier that could well heat our living room if left on with music playing. Now days, everyone has their headsets and listen to what they want instead of what I liked as they used to back in the day. Oh well guess I will try to put some DuPont ends on some of this wire and see if I can use it in building projects with my Arduino collection. I am very disappointed in my results trying to use cat 5 wires removed from those cables, the wire just does not hold up well at all, and using lacquered wire does seem to work OK, I get a bit nervous with the appearance of thick copper wire in a power supply without the insulation I am so used to seeing around it. Of late I have been making 12 and 24 volt power supplies using 18650's that I scrounged from old laptop batteries, beats having to plug in a power pack every time I want to start one of my home built devices.
hi julian , love your videos. nice to see you do some work at the vocoders again. i have had half a lifetime of doing some stuff with synthesizers in an attic studio. the vocoders of the past have had my interest fir a long time so i know a little bit about them. i think, creating a good robot voice, like done in some movies, is an art ... as you said before they where developed for purposes of compression of information and nowadays they come in the form of voice compressors like lernhout and haupsie has made. and ham radios use them a lot . the vocoder i primary use now is in a korg radias. fully digital and serves all my purposes..my question, what is your interest in vocoders ?.. what you are doing here is not just hobby.. this seems like hard work i would say. some more questions.. what are you doing with the signal after the filters ? comparing it with a square carrier and output to mixer ? does each filter has its own carrier? is it the same as the filter frequency ? does it have enough harmonics ? my experience is that a ramped saw wave can also be a good carrier. that phase control you were showing btw.... maybe you should consider controlling that simultaniously for all bands with offsets and intermediate scaling....(if you have some time .....) , ghihihi hell of an instrument your building julian..greetz from holland
This project has fascinated me ever since it was first published. Remarkably, you can still buy ALL the parts. So I'm just realising a dream I had as a teenager :)
Are you putting bypass capacitors across the rails close to your opamps? That can improve the stability and prevent high frequency oscillations that shows up as distortion in the sound.
Maybe construct the Vocoder as per the schematic? using the values as shown in the schematic, maybe not missing out parts of the design, it might work as intened then. Im not bashing you I love what you do, you have kept me entertained and ive learned things from your videos but if you don't re create the thing as per the schematic then it's not going to work right?
6BE6 pentagrid converter makes the best band pass filter out there 5844 twin triode is a good driver stage amp or signal inverter I am using 47 k plate resistor grounded cathode on all 5844 sections I will let you know as I figure out more of the conversion
You'd love modular synthesisers, Julian. I could just see you building a Turing Machine module. Check out Robin Vincent's Molten Music Technology channel.
I was looking for a link to the original article and the link posted in the description doesn't seem to be too helpful, but I did find copies of the magazine for download at www.americanradiohistory.com/Archive-Electronics-Today/80s/ETI-1980-09-80.pdf, www.americanradiohistory.com/Archive-Electronics-Today/80s/ETI-1980-10-80%20(Original).pdf, and www.americanradiohistory.com/Archive-Electronics-Today/80s/ETI-1980-10-80.pdf (not sure why there seem to be two versions of the second one).
Julian, are you *_scared to use your scopes?_* You are spending all this time building (which is fine) but you fail to do *any* testing or diagnostics. You need to test and see the results using a signal generator (single frequency at a time). Looks like you are still just modulating a SINGLE frequency with the sum amplitude of four filters - not the most desired use of a vocoder. Read my comments in the last video.
I did have to resort to using the scope when I left the ground connections off the quad op-amps. That showed me full-wave rectification wasn't taking place. The situation now is that the breadboard is too small to hold enough circuitry to make a working unit. I need: more filter channels, preset pots for alignment purposes, full size pots for control purposes, the 12-0-12 power supply (it may behave differently on +-10V). I did read your other comments - the square wave oscillator(s) is split by bandpass filters into different frequencies (probably more sinusoidal after these filters). The project is still too embryonic to expect it to produce a good output - all the alignment pots are missing - all the control pots are missing too. Next step is to start mounting the proto-boards (which will have all the preset pots)on to decking timer (which I have) and get the spectrum analyser working. Control pots will be mounted on steel strips screwed to the sides of the timber. There's still a lot to do :)
Hanging on wall. It's another giant project with a mixture of analogue and digital elements. But 625-line CRT monitors are hard to find - it really needs a redesign to drive a VGA monitor.
This reminds me of an old tomorrows world piece about hearing aids, in the piece, Maggie Philbin (I think) spoke with her mouth covered while the audio track was highly compressed and clipped, completely unintelligible. But with her mouth reviled her speech magically became clear. Perhaps you could try this to see just how bad the audio can be and still be intelligible.
The Z80 needs a huge amount of support circuitry - ROM, RAM, keyboard, VDU interface, printer interface, cassette interface, floppy disk interface, ROM burner, big PSU etc.
V Madison - Tantalums are apparently better than aluminium electrolytics when in the audio path. It doesn’t matter much in this application, I guess, but high end audio circuits like broadcast quality gear use tantalums.
