Hi all...
Apologies for any typos...
For those intersted in the AudioScope the next construction is finished.
I have not been totally idle but working out the hard stuff to be able to be very simple to build.
It is a single transistor simple timer that lasts for about 1.2 to 1.8 seconds.
The time length is not important as one can code around it.
How it works.
When AudioScope.sh is run several test files are generated and placed into the '/tmp/' drawer. One of these files is a one second 2KHz square wave RAW file at 8 bit depth, unsigned integer and 8KHz sample rate.
It is set to this so that '/dev/dsp/' and 'SOX' can use ot directly. I have decided that all of the ALTDC modes MUST be used with SOX capture only, so for these extras SOX becomes a dependency.
The filename is called squarewave.raw. When used in normal, ('/dev/dsp'), mode it is a 1 second 2KHz poor example of a square wave. HOWEVER, it is called using SOX and at 48KHz sample rate.
This creates about a 170mS burst of a square wave at 12KHz. This is fed to the earphone output on the MBP and from there to the DC_Control board.
This board is a voltage doubler and its output at around 2.5 Volts for 170mS is fed to the timer board. This fires the timer board to hold a relay for about the times mentioned above.
The two sets of relay contacts are completely isolated and can be used to switch the input and/or ouptu from the AC signal to the DC one.
There are two captures when in ALTDC and SOX capture mode; the first capture is the normal AC one through the Y amplifier.
The second is the timer switcher to allow the current guise, the VFO, to have enough time for a 1 second capture for the frequency counter to count the number of cycles of this burst.
It is then converted to a voltage to the accuracy of 4 to 5 bit depth.
The positive DC component is displayed in the yellow part of the COMMAND window for a couple of seconds and AC component, (if any), in the DISPLAY window.
I hope this is lucid enough...
The code to do this will be added to AudioScope.sh soon here is the test code...
#!/bin/bash
# trigger_test
# Simulate a hires AC capture...
/Users/barrywalker/sox-14.4.0/sox -q -V0 -d -t raw -r48000 -b8 -c1 -e unsigned-integer -> /tmp/waveform.raw trim 0 00:01
# Use the 8000 byte 1 second lores squarewave.raw file for a 170mS burst pulse at 48KHz sample rate giving a 6KHz frequency.
/Users/barrywalker/sox-14.4.0/sox -q -V0 -b8 -r48000 -e unsigned-integer /tmp/squarewave.raw -d
# Temporarily connect the VFO for this basic test to convert the VFO symmetricalwave.raw to the DC readout.
/Users/barrywalker/sox-14.4.0/sox -q -V0 -d -t raw -r8000 -b8 -c1 -e unsigned-integer -> /tmp/symmetricalwave.raw trim 0 00:01
EDIT:
The Dc Control board circuit, now added to the script...
# #########################################################
# The SEVENTH extremely simple circuit diagram.
# The DC Control circuit for the ALTDC modes.
# This DC controlled switch is for switching the input of the Y amplifier to
# the output of the ALTDC board and the input to the ALTDC board to the probe.
# +------o------+
# | | |
# \ | |
# / | |
# C = Common. +------O NO R3 \ + | o
# NO = Normally Open. v / --+-- S1 /
# NC = Normally closed. NO \ D1 / \ o
# ^ / '---' |
# C O---o----<o> RLA1 & RLA2 Isolated Contacts. | | |
# v +--+--+ | |
# NC ^ TP1 Optional. | RLA | | | +
# +------O NC O +--+--+ | __|__
# | c | | ===
# | o--o------+ |
# R1 * RV1 Optional. | b / BY1 |
# From Trigger O-----/\/\/\---o---/\/\/\---o------o--o--o__|/ Q1 __|__
# Control Board. | ___ | | |\ ===
# | | | \ \| |
# +-----+ | + / --o--+ |
# C1 === R2 \ e | |
# --- / | |
# | \ | |
# | / | |
# | | | |
# _GND_ O-----o---------------------o------o--------------o-------------+
# __|__
# /////
# PartsList:-
# R1 ......... 2K2, 1/8W, 5% tolerance resistor.
# R2 ......... 1M, 1/8W, 5% tolerance resistor.
# R3 ......... 47R, 1/8W, 5% tolerance resistor.
# RV1 ........ 2K2 preset variable resistor, (* optional).
# C1 ......... 220uF, 10V electrolytic capacitor.
# Q1 ......... BC549, or any small signal silicon NPN transistor.
# D1 ......... 1N4004 or any similar silicon rectifier diode.
# RLA ........ DPDT, 5 Volt coil, relay.
# S1 ......... Miniature ON/OFF switch.
# BY1 ........ PP3 battery.
# PP3 battery connector.
# Link Terminals, as required, (TP1 Optional).
# Stripboard, (Veroboard), as required.
# Various coloured and tinned copper wire as required.
# Small cable ties, optional.
# Stick on cable clip, optional.
# #########################################################