This is a really interesting thread, I have this darn AF01 A/D converter
for a negative bus pdp8 and your issues and methods with testing would
work well for testing this thing. Bonus it does appear to have a 16 or
64 channel mux capability.
Question: Is it possible to change the driver boards for ones that do
positive bus logic or is it simpler to build a DW08 converter clone to
hook it up to my pdp8/L for testing?
C
On 2/13/2022 12:04 PM, Douglas Taylor via cctalk wrote:
On 2/8/2022 7:36 PM, Jon Elson via cctalk wrote:
On 2/8/22 16:35, Douglas Taylor via cctalk wrote:
On 2/8/2022 5:22 PM, Jon Elson via cctalk wrote:
On 2/8/22 13:34, Douglas Taylor via cctalk wrote:
Update on this: I did put together a battery and voltage divider
to test the AXV11. The label on the A/D module says it brings the
output from the multiplexer to one of the external pins. I was
able to verify that the voltage applied to a couple of the A/D
inputs makes it through the multiplexer when selected using the
CSR. The next output available is from the Sample and Hold, and
this is always pegged at +12v. Am I wrong to assume that the
sample and hold will 'freeze' its output when the A/D go bit is set?
Well, it will probably only hold the approximate voltage for a few
seconds, but should be long enough to see on a voltmeter.
Jon
I was only using a voltmeter to look at it.
I'm going to try 2 different measurements; (1) use a scope to look at
the S&H signal on the AXV11 and see what it does over time, (2) look
at the same S&H signal on the Data Translation board which seems to
be working.
The S&H will likely have a FET as the switch element, and those might
be fairly easily damaged by external pulses. I opened up some
comparable Xincom modules and made minor repairs.
Jon
Stopped fooling with the AXV11 for now. Applied various voltages to the
Data Translation input and recorded the A/D octal values to get an idea
of what the calibration of the board is. It looks very linear, +/-10v
range.
Using a single battery and voltage divider I was able to generate
voltages on the input of the DT2762 board, however, I had to swap wires
to get negative voltages. Is it possible to construct a battery driven
circuit that will present both positive and negative voltages at the
input? A bridge of some sort?
Doug
