开云体育

Williams tube.



Grü?e, Carsten

You might be talking about the loose tube in a box at the bottom of
the picture. I mean a rack mounted unit between the two PCs.

Yes. See the picture at
(because of the inexplicable restriction on sending attachments on this list, I just put it up in a random location. Copy that into the groups.io archive if you can stomach navigating that entirely unneeded bureaucracy) — zoom in to see the faint green image of the bits.

There are
two scopes and a third thing, in the rack, that also looks like a
scope. A Williams tube device has no front display because the front
of the tube is covered by the read-out plate.

The problem is — how do you debug a Williams tube?
I seem to remember that the makers of the Manchester Baby (SSEM [1]) just put another tube on the same signals so they could see what was written to the storage tubes (ah, [2] has the details). During restoration, they couldn’t get the original size display tube, so they have a half-size in the rack now.

BTW I tried getting in touch off list but haven't heard back :) Would
you mind checking :) thanks

Everything is on its way, thank you.

Grü?e, Carsten

[1]:
[2]:

You are right about Q1-4, I was in a rush, will fix it tomorrow.
I can test things with a simple current mirror, but I usually resort to a
Wilson if I am not using matched parts. Just habit, perhaps a bad one.

On Tue, Jul 27, 2021 at 23:33 Ed Breya via groups.io <edbreya=
[email protected]> wrote:

Looks about right, except the PNPs appear upside down. If you're going
with emitter ballast resistors in the mirror, then you probably don't

need

transistor matching or the Wilson configuration, and two NPNs per mirror
would suffice. The compliance is pretty much constant since the row and
column nodes hold very close to ground - there's hardly any Early effect.

Ed





--

Andy

Here is the schematic for the digitally controlled current sink:


That needs to be duplicated for each row/column.
Using 1% E96 resistors and unmatched transistors, it is accurate to
within +/- 10uA in my testing, so I do not think I need to resort to
matched parts.

Values of R5-R8 would need to be tweaked if your logic was 3.3V, but I
plan to design to 5V parts.

On Tue, Jul 27, 2021 at 6:26 PM Andy Warner <andyw@...> wrote:

Simple mistake on the prototype wiring was the cause of the poor TS pulse
detection previously reported.

Here is what it should look like:



This is basically the TS to TTL conversion circuit from the 7M13 readout
module (correctly wired this time.)

Now we have nice sharp edges, and about 35us from the rising edge of the
blue trace (the logic level output) to set up the current sinks
appropriately, which I think is plenty of time.

I am planning to use SPI port expanders, to reduce the number of I/O pins
required on the microcontroller, and also make the circuit more universal,
so I am planning to use an input pin per timeslot. The 7M13 uses a trick
where it diode ORs TS2-10 together, thus requiring only 2 pins of input,
TS1 to flag start of readout, and all the subsequent timeslots simply
increment a counter, no need for interpolation. However, I am planning to
give each timeslot its own pin, that way the circuit can diagnose missing
timeslots and other issues.

On Tue, Jul 27, 2021 at 4:39 PM Ed Breya via groups.io <edbreya=
[email protected]> wrote:

I think you'll need at least two TS detectors (like maybe the first and
last), so you can figure out the actual running frequency and

interpolate

the rest of the slots. In my readout exerciser, it is all inside the
plug-in, and uses all of the TSs for direct coding, so it was
straightforward - except for needing 14 interface signal lines.

Ed

--
Andy

--
Andy

Simple mistake on the prototype wiring was the cause of the poor TS pulse
detection previously reported.

Here is what it should look like:



This is basically the TS to TTL conversion circuit from the 7M13 readout
module (correctly wired this time.)

Now we have nice sharp edges, and about 35us from the rising edge of the
blue trace (the logic level output) to set up the current sinks
appropriately, which I think is plenty of time.

I am planning to use SPI port expanders, to reduce the number of I/O pins
required on the microcontroller, and also make the circuit more universal,
so I am planning to use an input pin per timeslot. The 7M13 uses a trick
where it diode ORs TS2-10 together, thus requiring only 2 pins of input,
TS1 to flag start of readout, and all the subsequent timeslots simply
increment a counter, no need for interpolation. However, I am planning to
give each timeslot its own pin, that way the circuit can diagnose missing
timeslots and other issues.

On Tue, Jul 27, 2021 at 4:39 PM Ed Breya via groups.io <edbreya=
[email protected]> wrote:

I think you'll need at least two TS detectors (like maybe the first and
last), so you can figure out the actual running frequency and interpolate
the rest of the slots. In my readout exerciser, it is all inside the
plug-in, and uses all of the TSs for direct coding, so it was
straightforward - except for needing 14 interface signal lines.

Ed

--
Andy

Silicone valley is obviously located in Hollywood.

Harvey


On 7/27/2021 9:39 PM, Dominic O'Kelly wrote:

Ha! Oh dear... I wrote that on my phone so perhaps I can blame autocorrect.... either way it's a good case for proof reading one's work.

Yes I'd imagine silicone valley is in a different part of California... more focused on the front end work ;)

Ha! Oh dear... I wrote that on my phone so perhaps I can blame autocorrect.... either way it's a good case for proof reading one's work.

Yes I'd imagine silicone valley is in a different part of California... more focused on the front end work ;)

Awesome that would be great. I am kind of out of my depth on this one. The connectors on the board are

Large connector in the front of the scope - AMP 3-530662-0-8301
Small connector towards the back of the scope - AMP 2-530662-5-8110

So making slow progress

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Ke-Fong Lin
Sent: Wednesday, July 21, 2021 3:17 AM
To: [email protected]
Subject: Re: [TekScopes] Recreating an old board for the 7854

I need to figure out how to make Kicad do a PCB edge connecter.

You can use Python scripts to generate the Kicad footprints for the PCB edge connectors.
I've done it for my TM500/5000 and 7000 series extender projects.




You should be able to re-target these scripts. I can even help you do so if you want.

I need to figure out how to make Kicad do a PCB edge connecter.