Rob, obviously will work. :) But it would be weird to use a bunch of external analog electronics. BTW, with a PIC you can do a class D amplifier... what perhaps Hans wanted is not far away: sampling and then digitizing via PWM. Other choices are possible as well. Success on any variant you'll choose!
On Fri, Feb 25, 2022 at 7:58 PM Rob CJ <[email protected]> wrote: > Hi Kiste, > > The reason that I think it still might work is because - what I mentioned > previously - is that my Apple II I had built in the past also just worked > with tones to store data (at that time only games 🙂). > > I copied a pice of the casette interface of the Apple II schematic diagram > I found on the internet. What you see is that with an opamp the audio is > input signal is converted to a digital signal and the rest of the > processing is done in software. There is no special chip on the board to > process this data stream. > > Also the data out is just a direct output of a flip-flop with some > resistors to reduce the signal outpt but not even a low pass filter. > > The variations in cassette speed will result in a variation of the tone so > if I use a tone range to detect the right tone it might work. > > Kind regards, > > Rob > > > > ------------------------------ > *Van:* [email protected] <[email protected]> namens hans < > [email protected]> > *Verzonden:* vrijdag 25 februari 2022 16:20 > *Aan:* jallib <[email protected]> > *Onderwerp:* Re: [jallib] PWM serial audio transmission > > > Hi Vasile, > > In my time a birth was still followed by a placenta, nowadays an iphone > comes after. > > A long time ago I was infected by Wouter, Jal is even more persistent than > corona, see http://www.voti.nl/setalk/n_index.html > > > > regards Hans > > Op vrijdag 25 februari 2022 om 13:34:14 UTC+1 schreef vasile: > > Hi Hans. Congratulations for your young mind! There aren't many people > programming at your age. > You are a great example! > > On Fri, Feb 25, 2022 at 10:16 AM hans <[email protected]> wrote: > > Hi Vasiele and others. > I was born before the last world war and I suspect most of you after it. > I hope it stays that way!! > Great, I can study today again. Thank you. > > Op vrijdag 25 februari 2022 om 06:58:52 UTC+1 schreef vasile: > > Kiste, not only the ZX81 but Sinclair Spectrum and most of it's clones did > the same. > The biggest problem was the tape speed variation (among the volume > variation which was corrected in romanian clones -and we had more than any, > I recall 5 different types). > > Hans, on the actual PIC18 series on which JAL works ( presuming you will > do with JAL) you might have some sampling speed issues. You need at least > 7.5us for an ADC sample and according to Nyquist theorem you need not 2x ( > which is pure theoretical) but at least 4x faster sampling than maximum > frequency you are recording. > After your AD is sampled, the PWM is not an issue, but you might > experience a small delay between real recorded speech and the PWM filtered > one. > If you plan to add voice for your puppet, then limiting to 4KHz may be a > good choice. > > best wishes, > hopefully not WW III, but in pace for playing nice... > > On Thu, Feb 24, 2022 at 10:38 PM 'Oliver Seitz' via jallib < > [email protected]> wrote: > > Hi Rob, > > connecting two PICs is not like an audio recording. Better connect the pic > to your soundcard to record and then playback, that way you'll get > something similar to a tape recorder. > > The difficulties when using audio equipment are (at least): > > - only alternating current is transmitted > - the volume is never exactly the same > - the frequency range is limited to like 100Hz-10kHz > - the line level voltage is less than 1V > > Reading should be possible by most PICs which have comparators. Only a > resistor is needed, then you can detect zero crossings. > > The Sinclair ZX81 used audio equipment as storage. A burst of three > oscillations coded a zero, five coded a one. The output was low-pass > filtered. You usually had to try loading a program several times, slightly > adjusting the volume, until you got lucky. > > Greets, > Kiste > > Am Donnerstag, 24. Februar 2022, 19:56:01 MEZ hat Rob CJ < > [email protected]> Folgendes geschrieben: > > > Hi Hans, > > If I understand you right the only thing you want to do is to record a > signal or a sequence of signals on a casette player that can be used to > trigger something when the recording is played back right? > > If my initial suggestion would work - which may work since I have the idea > that my Apple II did more ore less the same thing - I could give it a try > to do a proof of concept. > > I may have a the problem that I do not have a casette recorder but I could > fake it by just connecting two PICs to see if that works. The final test > could then be done by you. > > Which PIC type are you using? > > Kind regards, > > Rob > > > > ------------------------------ > *Van:* [email protected] <[email protected]> namens hans < > [email protected]> > *Verzonden:* donderdag 24 februari 2022 17:07 > *Aan:* jallib <[email protected]> > *Onderwerp:* Re: [jallib] PWM serial audio transmission > > Another piece of text: > So far I've done everything with MIDI. I used one midi channel for the > actions with a general command type. Then 2 data, one for the device nr > (16) and one for the command. (0-128) > This has worked well for years, but it does require a complete MIDI sound > package. > > Op donderdag 24 februari 2022 om 16:55:46 UTC+1 schreef hans: > > Hey , > I have tried a circuit with an MT8880 but the ICI has failed. I did hear > the 16 tones, but when I wanted to receive them, the chip gave up the ghost. > In theory I understand your suggestions well, but developing something > like this is not easy for me. I'm just a LEGO builder. > regards > Hans > > Op woensdag 23 februari 2022 om 19:30:37 UTC+1 schreef [email protected]: > > Hi Hans, Kiste, > > You can still by DTMF decoders and I assume also DTMF encoders. Just look > at for example Aliexpress and type DTMF. > > But another suggestion. Many, many years ago I had built an Apple II and > I used cassette tapes to store and load games which was using tones > generated by the Apple II itself using two tones, one for high, one for low > and one as a lead-in tone (not sure in the lead-in tone was another tone) > to synchronze the start of the recorded program. You would not need this > lead-in tone in your case > > So I think it may not be that complex: > -) For recording on casette, generate this dual tone by the PIC via PWM > or maybe it is also sufficient to generate one tone in case of a 1 and no > tone in case of a 0 but I think this will be less reliable. > -) For playback, measure the length of the recorded PWM tone. If is is > within a certain range you accept it as a one and in case of two tones the > lower tone could be zero and the higher tone is one. > > As long as the tone frequency is not too high, I think this could work. > > A more advanced solution would be to use a phase locked loop (PLL) but I > am not sure if it will work. The PLL locks to the input signal so the > voltage that controls the oscillator goes up and down to follow (lock on > to) the input signal and this oscillator voltage signal could then be used > by a comparator of the PIC to detect a high or low tone. You can also use > the oscillator of the IC to generate the two tones by controlling the > oscillator voltage by the PIC. A typical IC for that is the HEF4046. I have > used this IC many many years ago too. This solution may be bit over the top > since you only want a kind of trigger signal > > But maybe the first solution is more doable. Just give it a try. > > Kind regards, > > Rob > > ------------------------------ > *Van:* 'Oliver Seitz' via jallib <[email protected]> > *Verzonden:* woensdag 23 februari 2022 09:58 > *Aan:* [email protected] <[email protected]> > *Onderwerp:* Re: [jallib] PWM serial audio transmission > > Hi Hans, > > 20 years ago I would have suggested using DTMF, but the decoder chips are > rare these days... > > PIC controllers include various peripherals which can be used to encode > and decode DC-free signals (which, apart from the frequency below, say, > 10kHz, is the requirement to be recorded as audio). On/off keying or > frequency shift keying are the easiest, I think. Which chips are you going > to use? > > Greets, > Kiste > > Am Mittwoch, 23. Februar 2022, 09:15:43 MEZ hat hans < > [email protected]> Folgendes geschrieben: > > > Hello everyone, > I have been trying for a long time to place a serial signal on one track > of an audio recording which I can read afterwards. To make all kinds of > things happen at the same time as the audio is played. I have now tried to > do this with the old modem system ( TCM3105) but it failed hopelessly. I > read that there are also systems to do this using PWM. 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