Analog Delay Line - Page 1
Forum section: electronics / projects

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 04:23:48 am
content: I am making a video effects unit but i need to delay a video signal for about 1 - 5 frames. how should i go about this

author: BrianHG
author_rank: Super Contributor
timestamp: January 29, 2018, 04:37:11 am
content: Quote from: bopstar on January 29, 2018, 04:23:48 amEntire frames!Digitizing -> memory -> Dac will be the only way. Some exotic old 1 field memory ICs existed for NTSC color comb filter decoding and TBC hardware, but, they are exclusive Sony special parts which are hard to find today and they would cost a fortune and data sheets will probably mean trying to get Sony to give you data on their 1990 ICs and you also will need Sony's special line locked & subcarrier locked clock generating PLL which is specifically designed as part of the chipset.It is easier and cheaper to get a SBC with DVI/HDMI video input and output, and create your own effects through your own software code using the onboard GPU.You can get FPGA based digital video processing eval boards, but unlike the 100$ SBC, expect a price tag of at least 5k$ and everything will be using SDI in and out + DVI/HDMI + all your development will need to be done in Verilog/VHDL.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 04:48:48 am
content: its not the only way because a delay line is a wire and the the length will effect the time it takes for an electron to get from one end to the other. thus if you use enamile wire (copper) and wind it tightly around a tube and have many many wingdings you can produce a resealable delay. the formula i think is three times the eighth times 0.040625(one frame of video in seconds) which should give me the right length of wire to use Delay=Distance/Timecorrect any mistakes i have done. it helps

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 04:58:51 am
content: Electrons don't "get from one end to the other". The coil you are describing will just from an inductor, which will form a filter with whatever active load you have.What you need is a transmission line to have a delay you need, you need to coil a few hundred feet of a coaxial cable.It is way way easier to go digital.

author: llkiwi2006
author_rank: Regular Contributor
timestamp: January 29, 2018, 04:59:46 am
content: Have fun with 812.5km delay lineThere is a reason why they used to use piezoelectric transducers to convert the signal into acoustic waves to do the delaying.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 29, 2018, 04:59:53 am
content: You need a few thousand kilometers of transmission line, good luck with buying that, and with high frequency losses. Also, it's not electron movement, it's electromagnetic wave propagation.A videotape delay was more economical in the 50s to 90s (I don't know if they ever did it this way, actually, but the concept is identical to audio tape delays, which were used), and digital was more economical for high quality since the late 70s or so. (Which is saying something, considering how expensive digital memory was back then.) Digital is trivial these days: as mentioned, buffer devices are a few bucks, common as sand.Single line delays were somewhat practical since the 50s, due to the introduction of PAL decoders in color TV sets. These were acoustic delay lines, tuned for the chroma band (some MHz). Assembling 625 of those in a chain, with filters and modulators at each end to shift baseband video (luma) to the center frequency, and equalization and buffering between each delay line... would be interesting, I'll give you that.Note that even such minor delays (63us) were more economical to make with alternative technology (i.e., acoustic, not electrical) than with electrical transmission line. Some sets (NTSC, and probably PAL and others too) did use short delay lines for lining up luma (which required no processing) and chroma (which required filtering, demodulation and decoding -- incurring some delay), but this was a short delay, a microsecond or so. Even so, the delay lines were typically quite bulky (~20cm).Tim

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:08:19 am
content: this is where you are wrong i have managed to make a 450us delay which is a few scan lines of video delayed there using my method. so no i don't need hundreds of feet worth of wire to

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:12:03 am
content: this is an image of a 450us delay line for video of Wikipedia which was used in tv sets

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:14:13 am
content: Yes, but you can't have windings go on top of each other with this method. So you need a length of pipe proportionally bigger (or a bank of those things).Plus you need to take signal loss into account, which would be huge.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:14:46 am
content: i do

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:16:20 am
content: Quote from: bopstar on January 29, 2018, 05:14:46 amThen you are somehow violating the laws of physics. So why are you asking us how to do that, if you already can do this?

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:17:14 am
content: how am i violating the laws of physics with a tube that is 20 meters long

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:18:59 am
content: Quote from: bopstar on January 29, 2018, 05:17:14 amI thought you said that you do have windings on top of each other. That would be wrong. Long tube is fine.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:20:22 am
content: again i refer to the image of wikapidia accept mine is a much longer

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:21:23 am
content: Do you consider 20m long tube to be practical? If so, then we are done here. What do you want from us?

author: llkiwi2006
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:21:54 am
content: You wanted a 40ms delay, which would need a delay line some 100 times longer than the 450us delay line you posted. Are you willing to have 100 of those in your design?

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:24:49 am
content: i am not making a 40ns delay i am making a 40625 us tube witch i am asking how to calculate how many wingdings of wire to use and what wire to use

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:26:36 am
content: I fell like you are a troll. 40625 us is ~40 ms. And you need the same wire you used before, just multiply the length by 100.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:28:11 am
content: im not a troll. i just don't not what gauge to use and the exact leghnth. was my calculations correct because it would equal about 20.80m of enamel wire. is that right?

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:30:20 am
content: Quote from: bopstar on January 29, 2018, 05:28:11 amYes. There is noting you can do about it. That's why everyone is telling you to go digital.The delay here is not defined by the wire, but by the length of the transmission line itself (windings and the copper tube form a transmission line). You can use much thinner wire, but your loss will increase. And I doubt it will work at all at that length. You would need a few amplifiers along the way.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:32:13 am
content: ok then how will i delay a video signal by 5 frames then. i really want to know

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:35:18 am
content: Quote from: bopstar on January 29, 2018, 05:32:13 amDigitize, store in memory, play back and turn it into analog after 5 frames time.Or just do all your effects in digital form and output the final result.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:36:02 am
content: how would in go about that

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:37:29 am
content: Quote from: bopstar on January 29, 2018, 05:36:02 amThat depends on your level of knowledge. Study how ADCs work, study how memory works, study how DACs work. Combine all that knowledge.You may want to start with capitalizing your sentences.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:38:50 am
content: what do you mean by "capitalizing your sentences" ?

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:40:17 am
content: The first word of a sentence is capitalized in English language. Your question should have looked like "What do you mean by "capitalizing your sentences" ?".That's like 3rd grade of school. You need to know that before you can learn how ADCs work.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:41:55 am
content: i still dont quite understand

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:43:39 am
content: Quote from: bopstar on January 29, 2018, 05:41:55 amThen forget about ADCs and go back to school, they can explain it better than me.Or if you prefer to get your information from Wikipedia, then read thishttps://en.wikipedia.org/wiki/Letter_case#Usage

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:45:27 am
content: your very rude. i am quite a capable person and don't need you adding to the already large amount of bullying i get at school

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:47:32 am
content: I wonder why you get bullied with approach to problems like this.Well, I don't want to continue this conversation, if you are too lazy to press the shift key once in a while.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 05:51:51 am
content: https://en.wikipedia.org/wiki/Politeness

author: Nitrousoxide
author_rank: Regular Contributor
timestamp: January 29, 2018, 06:25:51 am
content: I must too recommend using digital methods. The scope of precision and size (as per mentioned before) would be nowhere near viable or carry any justification.I'd too suggest using an ADC -> FPGA -> DAC, that way you can achieve any other processing as per desired.Something like the Cmod A7 should be able to do the trick (it does depend on the synthesis size):https://store.digilentinc.com/cmod-a7-breadboardable-artix-7-fpga-module/

author: amspire
author_rank: Super Contributor
timestamp: January 29, 2018, 06:26:56 am
content: Unless you are happy with video of about 320P quality or worse, the only solution is digital.If this was the 1970's, we would be talking about a circuit with discrete logic ICs such as counters and 3 ram chips. you could be talking about a design with 100 IC's and a huge amount of circuit debugging.Times have moved on. You can make a far better solution with a fairly cheap FPGA chip, a video A/D chip, a video D/A chip and one (or 3) CMOS static ram chips. If you know how to design FPGA's, it is probably not that hard a job. You don't so you would probably want to start off getting a development kit and following all the Youtube tutorials. You will either decide you want to be able to design FPGAs and you will learn, or you will decide it is too hard and give up. You can start off with something like the $14 Cyclone II development kits on Aliexpress, or if you can afford it, the $50 type Cyclone IV (or later) based boards with more features.Someone somewhere may have already designed something that will do the job, but a specialized product like this can be enormously expensive to buy. Hundreds or thousands of dollars. Third choice would be to hire someone to design and build this for you. Again not cheap, but there are freelancing websites that let anyone in the world bid for your job. It can work out to be relatively affordable.

author: bopstar
author_rank: Regular Contributor
timestamp: January 29, 2018, 06:28:49 am
content: i cant use FPGA's (to expensive for me) what about the Paralax Proppeler

author: Nitrousoxide
author_rank: Regular Contributor
timestamp: January 29, 2018, 06:38:25 am
content: Quote from: bopstar on January 29, 2018, 06:28:49 amIt depends. I have no personal experience with the Parallax Propeller (a bit of an odd choice in part to be honest).It would really depend on the minimum time taken to perform a whole I/O cycle. The reason why I suggest an FPGA is because it is better suited for purposes like these, and you can get some particularly cheap FPGA's.However, if you'd like to go the microcontroller route, I'd suggest something slightly more powerful, say a TI MSP432P4 series part/launch pad.

author: amspire
author_rank: Super Contributor
timestamp: January 29, 2018, 06:39:43 am
content: Quote from: bopstar on January 29, 2018, 06:28:49 amWon't be enough without a lot of extra hardware.If hardware is too expensive, then you want to look at doing it on your PC using video streaming software like Avisynth. You could use a script file like this:Code:function delayvideo(clip thiz, float seconds){assert(seconds!=0, "delayvideo: invalid delay value")tF = abs(round(seconds*float(thiz.framerate)))delayed = seconds < 0 ? thiz.trim(tF-1,0) : blankclip(thiz, tF) ++ thizreturn delayed}This script is to delay by seconds so you would need to change it to delay by frames instead.You can do all the video mixing, effects, etc in Avisynth as the video streams through.This solution will only work if you can have a small delay between the stream from the source and the stream out to a monitor. I think it is probably the only solution cheap enough for you.

author: danadak
author_rank: Super Contributor
timestamp: January 29, 2018, 12:55:09 pm
content: Google "diy video delay line", some methods/answers there.Regards, Dana.

author: capt bullshot
author_rank: Super Contributor
timestamp: January 29, 2018, 02:29:06 pm
content: Quote from: bopstar on January 29, 2018, 05:38:50 amI guess something like-- "What do you mean by "Capitalizing your sentences" ? --instead of-- what do you mean by "capitalizing your sentences" ? --Anyway, for your original problem, I'd consider you to google for a "Frame Store Device", then either find and buy a suitable one, or try to figure out how these things work and roll your own. You may come up with detail question then. Depending on the (electronics) age we live in, this device might be built using a tricky magnetic tape arrangement, some kind of acoustic wave delay element, analog chips like CCD FIFOs, or some digitizer, memory and stuff, maybe integrated in to a decent FPGA.IMHO, "How do I build my own frame delay device" is a too general question for any internet forum. You can't expect people here to give you a detailed plan for such a thing, by chance matching your exact needs. One needs a good amount of knowledge to start a project like this or must be able to write some clear and understandable requirements to hire some contractor who builds the thing.For example:Is your signal to be delayed a digital stream (data rate?) or a analog video (colour or monochrome, which video system)?What is the exact amount of delay required, is this constant or variable, must it be synchronized to an external master signal?Is the required delay an exact multiple of a frame's duration?...

author: BradC
author_rank: Super Contributor
timestamp: January 29, 2018, 03:16:48 pm
content: Quote from: bopstar on January 29, 2018, 06:28:49 amI might have used a propeller or two. Won't work. Not anywhere near fast enough. The video generators in that chip are dedicated hardware designed specifically to spit out vaguely usable composite. There is no way to get data in there fast enough and out to memory then back out as a composite signal.

author: Avacee
author_rank: Unknown
timestamp: January 29, 2018, 03:24:56 pm
content: For those confused about the importance of capitalisation compare these two sentences:1) Did you help your uncle Jack off his horse?2) did you help your uncle jack off his horse?p.s. I'm no help on delay lines, sorry.

author: Bud
author_rank: Super Contributor
timestamp: January 29, 2018, 03:42:30 pm
content: I also wanted to suggest looking at Avisynth. If it is available for Linux , OP could get away with a cheap Rpi based solution (I only worked with Windows) He also said he wants to do processing, not just frame delay, so that may require enough dough for the task in terms of CPU/MPU cycles. Maybe Avisynth can already do what he wants.

author: John Heath
author_rank: Frequent Contributor
timestamp: January 29, 2018, 04:49:38 pm
content: what about air ?? the delay of air is 1 m second per foot as sound travels at 1000 feet per second. a rather high frequency speaker and high frequency mike placed 1 foot apart would lead to a delay of 1 m second. treat the audio / video like a photon in single mode fiber where the audio wave length is a little larger than the audio tube. this will prevent time dispersion. to keep the video in the same frequency range we can borrow a dirty trick used in VCRs delay lines. the dirty trick is to FM mod the video so the carrier is always in the same frequency range. from a theoretical point it should be possible. doable is a different story.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 29, 2018, 05:15:03 pm
content: Quote from: John Heath on January 29, 2018, 04:49:38 pmWhat is the frequency response of air? I think it is a brick wall after a few tens of KHz, this is why (at least if I remember correctly) you won't find ultrasonic sensors operating far above 50-60 KHz.

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2018, 05:16:36 pm
content: Quote from: John Heath on January 29, 2018, 04:49:38 pmThat won't be cheaper than $15 FPGA.

author: John Heath
author_rank: Frequent Contributor
timestamp: January 29, 2018, 05:57:49 pm
content: Quote from: TheUnnamedNewbie on January 29, 2018, 05:15:03 pmResonate cavities were used in TV front ends for frequency traps at 40 to 50 MHz range so for short distances it appears you can get away with it. Not sure of the finer detail of these acoustic resonators as they were unconventional but also very popular in most TVs of the time. Maybe someone in the group can shine some light on this . They were round about 1/2 inch in diameter in the front end of the IF section of TVs. Also popular in RF cable boxes.

author: LaserSteve
author_rank: Super Contributor
timestamp: January 29, 2018, 05:59:20 pm
content: I would go digital for the course delay, and use something from Allen Avionics for the fine adjustment... Your hand wound coil of coax is going to have horrible phase delay issues. Which would be far worse with just coiled wire.FYI 825 Kilometers of coaxial cable would require ~160 repeaters or signal boosters, This is based on the Bell System's 1960s to 1980s experience of using buried coaxial cable to send network TV and 600 phone lines per coax line in the bundle..Something like the L1, L3 or L5i "L Carrier" coaxial cross country systems, repeaters every 4 KM or so, remote controlled equalizers in manholes after every ~10 repeaters, Similar cables were still in use in Europe and Alaska up about ten years ago, where it was too expensive to replace them with optical fibers or microwave. When you have hundreds of kilometers of cable, the local ground temperatures affect the phase shifts. Hence the remote controlled equalisers working off RF pilot tones.Steve

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 29, 2018, 07:27:18 pm
content: Quote from: TheUnnamedNewbie on January 29, 2018, 05:15:03 pmI've heard of response over 200kHz, but I suspect you'll have a hard time with losses if it can be done at all in the low MHz.Also, acoustic waveguides are dispersive, so that sucks even more. It would be a mighty thin waveguide to be single mode in the MHz -- can you imagine hearing anything through a capillary tube?Tim

author: Someone
author_rank: Super Contributor
timestamp: January 29, 2018, 11:20:02 pm
content: Quote from: TheUnnamedNewbie on January 29, 2018, 05:15:03 pmIts a filter with steady attenuation like any other:https://commons.wikimedia.org/wiki/File:Atmospheric_sound_absorption_coefficient_2.svg

author: jmelson
author_rank: Super Contributor
timestamp: January 29, 2018, 11:42:06 pm
content: Quote from: bopstar on January 29, 2018, 04:48:48 amWell, almost. Commercial electromagnetic delay lines are built with aluminum-foil covered paper tubes with fine magnet wire wound around them. The wire is the distributed inductance, the wire-to-foil is the distributed capacitance, of the RC delay line. Old color TV sets had these tubular delay lines that were one SCAN LINE long (~65 us). They were about 4-5 inches long.So, you need about 500 of them! The downside with these delay lines is there is magnetic and capacitive coupling between adjacent turns of the wire, so the high frequency components of the signal spread out. In terms of time, generally the dispersion is about 5% of the total delay. So, one 65 us delay line would have dispersion of 3 us or so, meaning that a 300 KHz signal would have about a 50% loss. This is CUMULATIVE, so 500 of these in series would not produce any visible video signal.Jon

author: amspire
author_rank: Super Contributor
timestamp: January 29, 2018, 11:43:48 pm
content: What video quality are you after? Most of the old analog delay line techniques were used in an era of far lower video quality then we expect now.The PAL delay lines involved in producing the colour content on the screen were using the compromise that they could get away with far lower colour resolution than the resolution of the original uncoloured black and white image. We are talking about around the 300 pixels horizontal resolution.I was involved in Australia's first satellite TV in the 1980's. It was an analog format with separately time compressed luminance and chrominance content. They did use Plessey charge coupled storage ICs to be able to temporary store analog video. They were actually capable of driving a 50 inch TV screen at a very impressive resolution. But they only had to store 1 line of video. Not 5 frames. 5 frames is over 5000 times the storage that Plessey could manage. It is not just 5000 times more CCD cells but 5000 times the analog degradation by the time the analog charge has passed through millions of ccd cells.If you are after modern expectations of video quality, just forget analog delay methods. To put it another way, to delay 5 frames of 1080P video, you need to store at least 5 x1920 x 1080 x 3 x 8 bits of information = 250 million bits of information. You are effectively trying to store that much information in a tube of air or a coiled wire delay line or something. To store that much information, Digital just makes sense.It is too much information for any practical FPGA or microcontroller to store, so it will involve additional RAM.It can either be a circuit involving a fast microcontroller or FPGA connected to RAM, or the frames could be stored in the RAM of a PC.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 29, 2018, 11:52:28 pm
content: You already have a computer. Why don't you do what you think you want in software instead of chasing after decades-obsolete solutions for a dead video standard?Anyhow, welcome to my killfile.

author: John Heath
author_rank: Frequent Contributor
timestamp: January 30, 2018, 01:40:02 am
content: Quote from: T3sl4co1l on January 29, 2018, 07:27:18 pmGood point. What would the wave length for sound be with a max video band width of say 10 MHz? 1 KHz is around 1 foot for sound. I am going to weeny out and google feet to u meters. 1 KHz ,1 foot , 304800 u meters. 1 MHz 304.8 u meters. 10 MHz 30.5 u meters. Hmm , I suspect Walmart does not sell tubes with an inside diameter of 30 u meters. Leaving this aside what length of such a tube for a delay of 1 video frame ? 1 frame for 1/30 of a second , NTSC , is 32 m second. How far does sound travel in 32 m seconds. 343 meters per second so .343 per m second times 32 . I have that as .011 meters. This is doable . It just requires someone making tubes with an inside diameter in the 30 u meter range.

author: BrianHG
author_rank: Super Contributor
timestamp: January 30, 2018, 04:10:52 am
content: LOL, temperature would affect any sound delay technology, even an analog wire delay at the amount of time of 1 frame, the timing would drift the picture in and out of alignment horizontally by a few lines with each degree Celsius making all attempted methods mentioned above totally useless for video mixing effects. Just the change in capacitance of a fraction of pf over a wrapped inductor would throw the system completely out of whack since your final output image needs alignment down to within a 1-2 nanoseconds if you want the right color when mixing 2 frames. If you were even able to get your timing down to 35ns alignment, you could use such a delay for mixing B&W or 3 YUV component signals for color, but this would mean engineering 3 complete sets of perfectly matched parallel delay lines tripling all the difficulties involved.I guess thermally regulating everything down to a fraction of a degree centigrade and making the capacitance and spacing of every part involved in the delay adjusting for daily mechanical drift and aging, maybe you can get a system to function once for around a minute or so. After 1 frame delay, without a digitally line locked PLL clock, just the aging of a simple crystal or the 5v regulator's voltage drive would make such a 1 frame delay impossible to synchronize down to the necessary degree for a color composite signal to retain proper color.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 30, 2018, 05:35:26 am
content: Here's a classic example:Sylvania (I think!?), number 32-16108-2, 294-6894. Pulled from a 60s era, hybrid NTSC color TV set.The component measures 5.875 x 0.5 (L x D) inch, on 1/32" wall phenolic tube, with two terminals at one end, and one terminal at the other.Feels like around 36AWG wire, pretty close wound (approx. 230 TPI), 4.7" total winding length. This isn't just a solenoid, but there is a strip of foil, about 0.56" wide, beneath the winding.Note the foil doesn't go all the way around, making a shorted turn, or even a (gapped) cylindrical shield. This doesn't block the solenoid's magnetic field, so we can expect strong dispersion (a sort of helical waveguide mode, modified by the ground). What the foil does, is provide a ground reference, so the propagation velocity can be modest, at least at the frequencies of interest.Circuit: function generator --> 2.0k series resistance --> scope probe, delay line (open at far end). So, a 1/4 wave stub, source terminated, with waves reflecting off the open end. Therefore, the waveform will show twice the real (end to end) delay of the element.As you can see, the pulse delay is about 900ns. The highest frequencies (which are also the least amplitude, owing to the poor risetime of the generator, about 50ns) return sooner (less than 400ns delay), while the low frequencies lumber on through more slowly (perhaps 1000us or more for the lowest frequencies).As I said before, this modest delay was used to compensate for luma/chroma delay in the set. I wouldn't think a full-line delay would be all that useful for PAL sets, not without some serious equalization, or simply a better design.Note that this component has ballpark 50m of wire, or about 0.16 microsecond at the speed of light. It's doing a lot more than that, so the structure is doing its job -- more delay than the sheer wire length -- at the expense of serious dispersion. One for PAL purposes must be non-dispersive, at least to the tune of a few percent, and give or take equalization.Another big advantage of this type: the super high characteristic impedance. Two kiloohms! A perfect match for vacuum tube plate outputs, a necessity at the time (the luma and chroma outputs were tube in this set).I've only ever seen the acoustic type delay lines in VCRs, but I've not taken apart any old PAL sets, so I don't know if they ever used electric delay lines for that. It's a challenge, and a big expense.Note that this type cannot be constructed with multiple layers, due to the large external magnetic field that gives rise to the low propagation velocity. It's hard to imagine miniaturizing it much more -- using #44 wire and a smaller tube will only get you a bit more delay per size. A full scan line might fit inside a cube the size of your hand.FYI, a more comprehensive way to wind these -- the nondispersive kind, that is:- Start with a tube. Can be paper (wrapped with foil), or metal (tinned steel, brass or copper preferred).- Wind a pass of slightly over-large wire, bare. This is the shield layer.- Wind a pass of slightly-finer wire, enameled. Use high temperature enamel. This is the signal layer.- Wrap with solder foil, then copper foil. Use a stainless steel spring to clamp these foils onto the assembly.- Heat to soldering temperature, bonding the conductive parts together. (A wipe-down with flux may help, before applying the outer foils; or soldering in an inert or hydrogen atmosphere.)This effectively constructs a coaxial environment for the signal wire. Propagation velocity and HF loss will depend on the enamel.You can also do a bifilar or twisted (differential) pair (around any sort of core, including an insulator), but the crosstalk will be poorer.Tim

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 30, 2018, 05:51:27 am
content: Just to keep the crazy ideas going you could lease a transponder or two on one of the geosync satellites. One round trip is around a third of a second delay. Lots of jitter but conceptually sound.

author: BrianHG
author_rank: Super Contributor
timestamp: January 30, 2018, 05:54:49 am
content: Quote from: CatalinaWOW on January 30, 2018, 05:51:27 amThe sane affordable analog method.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 30, 2018, 05:57:36 am
content: Or moonbounce -- upside, the hardware is cheaper and more readily available than some of the methods discussed in this thread.Downside:the delay isn't adjustable.Tim

author: bopstar
author_rank: Regular Contributor
timestamp: January 30, 2018, 06:03:10 am
content: No i am just using 720x575 PAL video not 1920x1080p Video as i am trying to recreate old video equipment and effects. the hole point of the delay line is to create a video trail effect much like what was achieved in the late 60s and 70s to make cool looking video effects

author: amspire
author_rank: Super Contributor
timestamp: January 30, 2018, 06:51:02 am
content: Quote from: bopstar on January 30, 2018, 06:03:10 amYou mean the effect where they point the camera at the monitor? Just do the same thing.Otherwise, it sounds like you want to achieve something that avisynth can probably do for free at any resolution you want.

author: mrflibble
author_rank: Super Contributor
timestamp: January 30, 2018, 07:02:58 am
content: Quote from: bopstar on January 29, 2018, 05:45:27 amo o r l i y y a a n a e d s t p a p a a t w n l g r a t u r o o l r r y s n a w a n o l s e n

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: January 30, 2018, 07:54:04 am
content: Bopstar:OK, you are looking for about 5 frames of delay of 25 fps PAL. That's 200 mSec. Using anything like a wound delay line with the bandwidth required to pass video (6 MHz) wont work. As we have seen it would be over 20 meters long and very lossy. Even with amplifiers with frequency response correctors every 200 nSec (an optimistic guesstimation) that amounts to 1,000,000 amplifiers each of which would be about 40 sq. cm on pcb. I don't think you can finance that many. After a million amplifiers the noise level and distortions would completely obliterate the signal.You would have to go the ADC/memory/readout/DAC route. 5 frames of video sampled at 4 x the subcarrier frequency of 4.43181875 MHz = 17.72725 MHz (you couldn't go much less) would use about 3.55 Mb of memory. Lets assume you do 8-bit samples at that rate. ADC's that will do that can be easily had. For the sake of quick and dirty delay you dont even have to lock to the sucarrier frequency like everybody used to do in all of the studio equipment around the world, just be close and not too much less. The only thing you need to make really sure of is that the ADC and the output DAC are clocked from the same source.The complications come in when you consider that the memory has to handle writing the digitized video SIMULTANEOUSLY with reading the output video. This is no simple problem, but some years ago Micron made some chips that would do just that. They are not simple chips either. Here is the first couple of pages of its datasheet.https://4donline.ihs.com/images/VipMasterIC/IC/MICT/MICTD002/MICTD002-3-1.pdf?hkey=EF798316E3902B6ED9A73243A3159BB0I doubt if those chips are still made but maybe somebody is making something like them. Writing the data means you advance the write address each sample. Reading it means you advance an entirely INDEPENDANT read address each sample. There are times when the memory must be written to and read from at the same time. I don't meancloseto the same time. I mean the read and write cycles must overlap ON THE SAME NANOSECOND. To have variable delay you simply manipulate the difference between the write and read addresses.Even if we don't worry about a slew of issues that would normally be heavily designed in a broadcast-quality framestore unit we are still talking about a pretty sophisticated circuit. I guess a competent engineer could design and hand-wire it in about 3 months.There might be some possibilities in using a PC to ingest the video, store it on disk then read it out with some programmable delay...

author: John Heath
author_rank: Frequent Contributor
timestamp: January 30, 2018, 10:29:37 am
content: Quote from: T3sl4co1l on January 30, 2018, 05:35:26 amOld Fender guitar amps achieved a 100 m second delay for regenerative echo -6db 100 m s , -12 db 200 ms .... They did this with what effectively was a slinky spring 18 inches long with longitudinal spring modulation then feed back. It would sound good with one minor problem. If you put your beer on the amp it would rattle the springs so you would hear it coming out of the speakers. I call this the beer distortion problem. Later they used a bucket delay IC so the problem went away. A tube filled with mercury acts the same as a slinky spring approach and was considered as a type of dynamic computer memory when RAM was expensive. Maybe mercury could be used as a video delay line. It would have the beer distortion problem but other than that it should work?

author: Gyro
author_rank: Super Contributor
timestamp: January 30, 2018, 10:31:14 am
content: Quote from: bopstar on January 30, 2018, 06:03:10 amFind yourself an old CRT Monitor or TV and a cheap video camera (preferably one with a tube rather than CCD). There's no way that you will improve on this with any sort of delay line. There would be no easy way to replicate the effect of moving the camera slightly to get curved trails etc. I've done it myself and you can get some great effects, eg. the original Dr. Who opening images!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 30, 2018, 10:51:10 am
content: Quote from: John Heath on January 30, 2018, 10:29:37 amPossibly. The loss might be low enough to work, and bandwidth high enough? Still would want to avoid capillary tubes for loss reasons (but also for mechanical reasons, as mercury is heavy and it doesn't do much good putting it in, say, a metal tube that is also heavy and therefore carries the same acoustic energy..), in which case you have to deal with mode breakup, which, who knows.Speaking of which, at that point you might as well direct couple the piezo transducer to a solid, say, nickel wire (or use magnetostriction of nickel or other materials, directly), or whatever is suitable. A thin wire would be easier to deal with modes, and wouldn't suffer from problems that a liquid might, but you still have the problem of loss and dispersion. (I think you still get dispersion because of surface vs. bulk and longitudinal vs. shear waves being different velocities?)It was good enough that music wire was used as memory in some calculators, though probably at a pulse rate lower than in question here.Tim

author: John Heath
author_rank: Frequent Contributor
timestamp: January 30, 2018, 01:19:28 pm
content: Quote from: T3sl4co1l on January 30, 2018, 10:51:10 amMusic wire as calculator memory? That is a new one that I have not heard of. Managed to google up a picture of it.http://www.vintagecalculators.com/html/calculator_memory_technologies.htmlLook at those discrete transistors in type TRO-5 cases. Memories.

author: Kalvin
author_rank: Super Contributor
timestamp: January 30, 2018, 06:03:37 pm
content: You might be interested in the Synkie project "Open Source Modular Analog Video Processor", although they are using digital delay line:http://synkie.net/blog/video-delay-now-in-colour/http://synkie.netPossibly you could grab some ideas for your design.

author: BrianHG
author_rank: Super Contributor
timestamp: January 30, 2018, 08:12:28 pm
content: What about a bunch of KM/Miles of wound up fiber optic. With only a 6MHz bandwidth requirement, analog driving a laser diode and a high speed photo pin diode all operating in the linear region. Should be kinda functional at such a low bandwidth without the requirement of amps, just a kick-ass laser on one side. Though, we are talking about a few 100K$ of glass fiber as plastic fiber wont work at this distance.I can imagine as you are trimming the fiber to get 1 perfect frame delay, accidentally trimming the fiber a mm too much screwing up your project.

author: BrianHG
author_rank: Super Contributor
timestamp: January 30, 2018, 08:20:19 pm
content: Found them!http://www.averlogic.com/AL440B.asporhttp://www.averlogic.com/AL422B.asporhttp://docs-europe.electrocomponents.com/webdocs/1383/0900766b81383bf9.pdfIt's a 4mbit FIFO, for video field ram, just a write side and read side, no control logic, you just need to provide clocks and an ADC/DAC + syncs, which you can get a NTSC/PAL trans-coder IC from Analog devices. (ADC/DAC for NTSC/PAL, with built in PLL clock generator, + black clamp + contrast, brightness, color, tint & sharpness controls all in a 9$ IC, but it has 16 bit color out...)

author: John Heath
author_rank: Frequent Contributor
timestamp: January 31, 2018, 08:03:01 am
content: Not entirely relevant to the subject at hand but it just occurred that AM radio from 500 KHz to 1600 KHz is within video band width. This means I could record an hour of all AM radio stations within a dynamic range then replay it weeks later plugging the VCR video out into an antenna to receive any AM station from weeks ago. Hmm , an annoying buzz for vertical sync to keep the VCR video head in sync but other than that it should work?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: February 01, 2018, 01:56:14 am
content: Quote from: Gyro on January 30, 2018, 10:31:14 amOh jumping jeepers.... if he's talking about "comet tails" on old video footage, this wasn't an intentional effect, it was from the camera pickup tube itself.Bright objects and reflections would knock out so many electrons from the photosensitive area that the readout beam was repulsed... therefore becoming black and/or leaving trails as it discharged slowly.1960s is full of black blowouts on video. But even later tubes still had tails.egHow he thinks a delay line will achieve that is beyond me.Besides, tons of 1970s effects were done with the Scanimate. That's not happening with a handful of chips on a breadboard either.

author: drussell
author_rank: Super Contributor
timestamp: February 01, 2018, 01:57:37 am
content: Quote from: bopstar on January 30, 2018, 06:03:10 amThey didn't use delay lines to make the effects you are talking about...As pointed out already, that was done with point-the-camera-at-the-screen type effects. Easily. Using CRTs with various persistence phosphors. Nobody ever used miles of delay line to make effects.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 01, 2018, 02:05:04 am
content: Well, wrapping feedback around a delay line will produce a per-point* first order IIR filter characteristic. Which can be used to average pixel values, for a motion blur effect.*Again, to the extent that dispersion allows.A nonlinear filter would be better, actually, since you want to take the square of the amplitude (gamma correction) and do the averaging on that, then take sqrt again for output. It also needs to be done in RGB space, not video space (which will just corrupt the colors period -- you'll never have the colorburst line up near enough to work). This is an old pet peeve among image processing, by the way; it's still uncommon to see gamma-correct blending done with modern programs and hardware.Tim

author: John Heath
author_rank: Frequent Contributor
timestamp: February 01, 2018, 03:16:04 am
content: Quote from: evb149 on February 01, 2018, 01:46:06 amThis is what I like about eevblog. No matter what you say someone has been there done that. Your words put a smile on my face.

author: BrianHG
author_rank: Super Contributor
timestamp: February 01, 2018, 05:44:08 am
content: Quote from: T3sl4co1l on February 01, 2018, 02:05:04 amYup, correct, and here is a video explaining this point:

author: LaserSteve
author_rank: Super Contributor
timestamp: February 02, 2018, 03:58:35 pm
content: Quote: " pfft, youngsters!Expand your 'steampunk' horizons to more good old technology that actually existed! "Hey, even in my 40s I resemble that remark...Too bad we cant send Mr. Bop on a field trip to see the last working Scanimate... He might learn something about video!However I think they have a DVD he can buy about the machine. Might be a good investment in his case.Then he just needs to find a old B&W vidicon security camera on Ebay for 15$ and aim it at a TrinitronSteve

author: montemcguire
author_rank: Regular Contributor
timestamp: February 03, 2018, 03:26:40 am
content: I'm amazed that anyone is using analog video anymore! Definitely a troll here...