Shell Programming and Scripting

Hi Corona688...

No.

It is a series C loaded into 1M in the open cct O/P in the diagram. It is not a shunt C.
The series C and shunt R is a effectively a high pass filter but with a very low LF cut off frequency of around 5Hz. This is so as to maintain the shape of the SQ wave on the O/P.
An external load of 100K will make little or no difference to the O/P.

The C is effectively a short cct to AC but _infinite_ 'resistance' at DC.

The SQ wave is fed into the series C and the O/P follows the input with almost no attenuation at all. The I/P is grounded in this case through 100K.

When the DC voltage is 0V on the I/P the O/P is also 0V.

Any +ve DC voltage on the I/P is reflected on the O/P as an identical waveform to the I/P of the same amplitude BUT is now AC coupled on the O/P. Remember the C is effectively a S/C at 2KHz. In other words a 2V DC I/P will become 2V P-P centred about 0V. The peak amplitude remains the same. This makes for ultra-simple sampling and decoding through the sound card.

(Reactance); Xc=1/(2*PI*f*C) where f is in Hz C is in Farads.

So its reactance, (AC__resistance__)......

Xc=1/(2*PI*2000*(10^-6))

This is around 80 ohms. Effectively a S/C to AC but completely blocks any DC component.

However The DC component is now a copy of the I/P but centred around real 0V. That is 2V DC relative to 0V is equivalent to +1V and -1V centred on 0V.

Hope this makes sense...

I have been doing this stuff for at least 20 years on differing platforms.

Here is a GIF anim of a full application I wrote for the AMIGA and finshed in 2001:-

http://wisecracker.host22.com/public/SCOPE.GIF

It has a GUI of its own, buttons that stay depressed when _pushed_. The waveform is a real one generated from a second AMIGA. And a FULL project for anyone to build on AMINET. A fully calibrated DC - 100KHz Oscilloscope where everything inculding simple calibration gear is built. This was aimed at the more experienced constructor.

Bazza...

I somehow missed the 1M. Excuse me. You are correct.

Hi Corona688...

Ha ha, I am glad we have cleared that one up... ;o)

Text mode circuits are not easy to read, but sure are easy to place into a script... ;o)

I am only going to use the original or second cct for the time being...

I am coding for it ATM but I leave my options open for the last one. The only problem is that the last one takes much longer to build than the simple or second version.

If I do a FIXED reference for the I/P voltage rather than connected to _GND_ then this makes for the ability to make the BW using this part from DC to about 200 Hz. This would allow for the Mic input roll off which I assume to be around 300Hz. It would take 2 scans to do, firstly the the normal AC capture, then switch to the chopper and scan the DC to LF component.

A reference voltage can be near anything from say 0 to +2.5V.

This should be relatively easy to code for using shell scripting as this now becomes modulated carrier of + or - DC offset centred on DC offset. This coiuld be regarded as a sampler in its own right. I was thinking of using a forward biased small signal silicon diode, like a 1N4148 for a reference of about 0.7V, accuracy is of no importance...

You now see where I am coming from... <wink>

I can honestly say that I don't think a project like this has ever been done before.

A shell script creating near everything to run and calibrate an audioscope from DC to 20KHz in pure text mode through the Mic input.

I have learnt a lot from you guys at shell scripting and all that bragging by me two years ago is now slowly converging to a sophisticated conclusion...

Admis and staff, thanks for allowing this to continue...

Bazza.

Hi everyone...

This is the still unfinished manual that is part of the AudioScope.sh.

I need a little help please.

I have copied it from the running file generated and would like a little bit of help from those following it.

It has been modified quite a bit and although still unfinished would some of you who are following it please proof read it for typos, spelling, grammar and if it seems to makes sense.

This is it so far to the version 0.31.27 which is not officially released yet.

Would you post on here if you find anything that fails.

To see the drawings the whole is best viewed in plain text format.

(Note: I had to add the '.txt' extension to get it to upload.)

TIA...

Bazza...

109: colour?
<multiple> automatically
<multiple> tolerence
444: though - unsure of usage
497: Thoroughly
868: requird
906: thge
1000: you could save easy 8 chars by removing unrequired - between pseudoground and R1 and between R2 and R3. (if that was an issue?)
1102: virtaul
1137: Verobaord

Unsure:
917: flanged
1185-1187: potentiometer

Note that i'm neither a sound guy nor is english my native language.

Hope this helps

Automatically is correct in UK English.

Tolerance: thanks a lot, no idea why I spelt it that way numerous times.

Though, thoroughly and flanged are correct UK English.

Required, the, virtual and Veroboard now corrected.

(Left the drawing '-' as is as it looks better.)

Ecellent job thank you very much...

EDIT:-

Version now at 0.31.27...

Your text sounded like you wanted to get rid of unrequired dashes..
Guess to foreign eyes, a word like thoroughly and automatically is like writing unnecessarily.

Copy & paste can be friend or foe

Welcome