for the most part i under stand what im doing , im planning on using a panasonic reader head to read some old magnetic tapes i have , im just curious to the contents and it shouldnt be terribly hard ,however i cant even get this logmatic to turn on the charge light is brightly lit and the usb light is dimly lit it dosent write any log files to the logger or any config files or anything
i got it to write to sd , it wouldnt write without the battery connected , but now i cant get my analog reader head to connect
Is this an attempt to write a progress blog, or to get help with something? Because it reads as the former. But if it is the latter, please be more detailed in the code you have written, what particular electronic parts you are using. And how it is hooked up/schematics/drawings. What you write does not provide any leads for suggesting ways of problem solving/bug finding. There isn’t a question in there.
i wish to connect a magnetic reader head to the logomatic and log data from some old magnetic tape i have, im using a reader head very similar to this http://cellwaytech.com/Cheap-Price-Magn … 51707.html as it stands i have nothing hooked up to anything i dont know how to proceed
You definitely need an amplifier to get a measurable signal out of this. (And a way to turn AC signals into DC for the ADC of the Logomatic to record) But the frequencies coming out of it are likely higher than the Logomatic can record. If can only sample up to 9999 samples per second according to the hookup guide. Audio frequencies can double that (<20KHz), and you need to sample at a rate more than twice the highest frequency present to accurately reconstruct the signal. But I suppose that also depends on how fast you drag the tape over it. Lower speed would result in lower frequency content, but require longer recordings. You probably will have better luck recording it with your line-in input of your soundcard. (still need an amplifier though)
well im not sure about the frequency , im not trying to read a cassette tape though just so i put that out there , this is binary data just 0s and 1s highs and lows , i thought the it would be interpreted as analog data just like any other analog sensor , i can record it as audio through my line in yea but then i need a program to translate it into data again which seems harder to figure out … your saying what im thinking isnt doable ?
Well, since you didn’t give any details of what might be on the tape I expect the worst. Frequency wise you probably can do it if you move the tape over it slowly. It does need AC to DC offsetting though, and a bit of amplification.
As for how the signal is modulated on the tape is another unknown. It might be modulated onto a carrier frequency. Iirc (from very faint memory) home computers back in the days used frequency shift keying, meaning a 0 meant a short period of the frequency 1200 Hz, and a 1 was a short period of 2400Hz. Or something to that effect. If that tape is of the type used in professional mainframe data reels then who knows how that was encoded (Google probably does) It might be simple encoding in which a 0 is a short period high, and a 1 is a low or negative. We just don’t know enough to make an assumption on that. Looking at it with an oscilloscope would be best. But lacking that, that line-in port is the next best thing to visualize the waveform. It doesn’t have the be the final way. But it does have more sampling resolution (16 bit vs. 10 bit on the logomatic) , and a larger sampling rate (44.1Ks or 48ks versus 10K on the logomatic). I think the line-input will work better for recording. How to interpret the data with a program is equally hard (well, almost) to both ways of recording. Your line-in port is recorded into a .wav file (or whatever format you prefer) with most sound recording applications. The structure of that is known, and there are plenty libraries for whatever language you will program in to manipulate the data therein. The logomatic stores it into a file on the SD card in it’s own custom format. (over serial will not be quick enough I think) Even though it is probably a much simpler format as a .wav sound recording, it too needs a program to interpret it.
I say play around with some soundcard based oscilloscope programs to get a better (visual) feel for the signal that comes out of the head element. Then make choices about the best way of recording it for real.
i recorded some of the data to my pc using a mp3 player solderd to a hacked up tape deck with this reader head this is what i got.
https://gyazo.com/874ffb902b2c135e97b70471135b65d6.
im an amatuer but it seems like its possible to me , its modulated as follows.
All data on this magnetic tape is coded by a sort of frequency modulation (F2F). This method use 2 frequencies for data coding. There are two frequencies: F for coding of logical “0” and 2F for coding of “1”. Figure 1 demonstrate F2F method. We will use the period (or time) taken between 2 peaks (T=1/F). The time for a period could be determinated by a series of 0′s at the beginning either ending of each entry (essentially just allowing the reader head to say okay i see them coming past at x ms). This is known as self-clocking and allows readers to read data that are pushed through by a human rather than say that of a tape player where it is a fixed speed. here is a diagram of what its talking about
https://gyazo.com/1742f7c9b16c3e09f05c2bc3a7639652
So, we can get data by comparing the time between peeks and current period T. If the period is equal to the time between peaks we receive 0. The logic “1” should consist from 2 parts, each of them equal ½ of period. In other words if we get 1 peak changes during period T than we receive “0”. If we get 2 peaks changes – that is “1”. The differences between “1” and “0” demonstrated on the fig2
So, we can get data by comparing the time between peeks and current period T. If the period is equal to the time between peaks we receive 0. The logic “1” should consist from 2 parts, each of them equal ½ of period. In other words if we get 1 peak changes during period T than we receive “0”. If we get 2 peaks changes – that is “1”. The differences between “1” and “0” demonstrated on the fig2
https://gyazo.com/27373aa8bfaf5521a9d38a6d0c606651
So, we can easily decode binary from the following data entry based off this
https://gyazo.com/24dccd94c2c0d7ef9b85d0a870582574
The result should be: 11011001011000 Each entry has sequences of “0” at begin and end of a record. This is a key for decoding initialization. software can determinate initial value of T for a record based off this . The value of T should be adjusted during decoding process. So, we can get a sequences of “0” and “1”. Next step in decoding this data should
include a program with a ASCII decoding routine.
the person who gave me the tapes included this with them
See what difference it makes if you can look at the waveforms? 
i can interpret the waveforms manually it is coherent stuff im getting but if im able to log this using the logomatic in theory wouldnt it interpret it to ascii for me because basically the reader head is outputting analog data if the logomatic is able to interpret the reader heads output as such it should log it no ? im trying to not have to interpret it as audio but as analog data and go from there , but it seems to be between 8-16khz , im curious if its possible to even hook up the reader head in the fashion thats required for it to be used and do what i want to . reading into what you said above it would be hand fed through the device , so possibly it would vary lower from 3khz to a max of 16-18khz if its based on the speed. i know its possible to do this with a pic microcontroller and do something off that with a reader head to record digitally as i posted this on free lancer but the guy wanted like 2500$ USD to design something for me and to me it seems like im a circut diagram away 
persay
maybe ill have to use an arduino as well ? anyways ill keep doing this when i can let me know if anyone has input
The logomatic does not interpret is. It just measures the voltage like a Voltmeter , but only the positive side and up to 3.3 volt (I think). Al you get is a number, which is either shown as a readable number in ascii format or as a binary number, depending on the configuration chosen. Interpreting it’s meaning is up to a program on the computer processing it, or a user looking into the log-file. Have you looked and read the hookup-guide?
Why don’t you just try it? You have the Logomatic don’t you? Try and see what comes out. Instead of going for the magnetic tape head immediately, try with a potentiometer first. Then you have control over the voltage that is being applied. (If you don’t turn the potentiometer the wiper voltage is static) And you can measure it externally with a voltmeter, and compare it to the numbers logged into the file. Only once you understand what is happening should you start to plug in the magnetic tape head.
An arduino (Uno) won’t give better results. If you write the code yourself it is probably going to give slow or irregular sample rates. To get the best out of the ADC inside, and the data to your PC in propper order, you would need to be pretty advanced in programming it. Not something for noobs. You may make up your own mind if you belong in that category or not.
What are the tapes from? Are they programs from some computer system or data?
Why do you expect the data to be in ASCII format instead of binary?
Binary data could be related to the particular target CPU that the tapes came from - big endian vs. little endian format, etc.
OR could very likely be the program in machine code such that you would need to acquire an instruction list for the processor used, just to even attempt to decipher the program and even at that it may appear to be nonsense.
Valen you have been nothing but helpful , i fall in the latter unfourtantley , most of my knowledge is self taught if i decide to further this ill hire a freelancer , i understand the concept of how the logomatic works i just got excited at the idea of ADC logger and didnt take the time to reliase theres more to it then i want it to work nevermind that im pretty sure the data on these tapes is -0.05 to 5v so it wont work , the tapes are from soviet russia danv from around the end of the cold war lol i have the documentation that goes with it stating its in binary code what i posted above for valen that mentioned f2f and stuff is whats with it it just something ive always wanted to try and figure out who knows whats on them it might just be useless data or it might be something cool
it looks like this project may be more along the lines of what im doing http://www.blog.exrockets.com/blog/simp … h-12b-adc/
The first parameter is the sampling time, which is expressed in milliseconds. The minimum sampling time is 5ms (200 samples per second)
An arduino could be quicker if it sent the data over serial immediately (and not going overboard on adding frame-header bytes to the sample data).
andrewfed:
it looks like this project may be more along the lines of what im doing http://www.blog.exrockets.com/blog/simp … h-12b-adc/
That device is slower than the Logomatic and always will be. Even with better software because the PIC18 was insufficient memory for buffers. This is critical to high recording rates on SD cards as they are faster when writing data in chunks larger than the 512 byte minimum. The Logomatic on the other hand has plenty of memory for buffers. [Code I wrote for version one of the Logomatic hardware was capable of 160,000 SPS.](http://home.earthlink.net/~schultdw/logOmatic)
UhClem:
andrewfed:
it looks like this project may be more along the lines of what im doing http://www.blog.exrockets.com/blog/simp … h-12b-adc/That device is slower than the Logomatic and always will be. Even with better software because the PIC18 was insufficient memory for buffers. This is critical to high recording rates on SD cards as they are faster when writing data in chunks larger than the 512 byte minimum. The Logomatic on the other hand has plenty of memory for buffers. [Code I wrote for version one of the Logomatic hardware was capable of 160,000 SPS.[/quote]
are you saying i would be able to sample the data im looking for on the v1 with your code ? sorry im pretty un experinced , and valen i seen a jury rig of an arduino that was used in decoding binary data but i cant reach the maker i have a decent picture though
https://gyazo.com/7576bfc0c9c99adb9bd23aded57d4b55
and another version i seen
https://gyazo.com/11282eab76df10300e793ba524ab7923
these guys did these so it was able to interpret magnetic head data into binary and save it into text in a buffer or sd card or transmit it to there device and save it it to be decoded later
not sure what the components are exactly but its been done before maybe you guys can recognize them , theres some guides on instructables for some arduino based magnetic card readers to my understanding someone i talked to on github made one said the process would be the same and possible but the reader head is different and wouldnt be compatible without modification to the code because regular magnetic card readers are ttl based and use a clock and commands to read the info not just electrical impulses like a tape reader head. so im still not sure what to do exactly](http://home.earthlink.net/~schultdw/logOmatic)
andrewfed:
are you saying i would be able to sample the data im looking for on the v1 with your code ?
I am saying that both the V1 and V2 hardware is up to the task with the right firmware.
that is excellent to know i unfourtantley am an admitted noob i plan on taking c some day here before i get to old but thank you its good to know im thinking in the right direction.
and lets say i have a V1 how do i hook the reader head up anyways