开云体育

They're computers.? Stored operating system came in with digital computers (and by that definition, the early ones, programmed with plugboards, were NOT).

Harvey

The great thing about the "human computer" is that we don't need updates!? Maybe a generational re-alignment or two...
-Dave

Yes, the DA was a mechanical analog computer. You programmed it with a wrench (and typically a bunch of grad students).

If something computes, wouldn't it be odd */not /*to call it a computer? A DA certainly computes (up to fifth-order differential equations, IIRC).

Requiring that it have a stored operating system is much too restrictive. We had computers long before the advent of digital things, and therefore of OSs. The first computers were humans, after all!

-- Cheers
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070

Is a differential analyzer a form of analog computer? There is a good scene of one operating in the beginning of the film "When Worlds Collide". Other amazing analog computers are the mechanical fire control computers for battleships and submarines, and the Norden bombsite. Despite all of these, can they correctly be called computers? The definition of a computer I was told some time ago is "A control or calculating apparatus with a stored operating system"

?? Bruce Gentry, KA2IVY

2465A DMS. Is there a Battery storing calibration data; and Does a record of calibration data need to be made to restore the device if the batter goes flat?

When you think about it, the analogue computer is really a Laplace Transform.

EJP

Hey Frank,

The -22V supply does have an adjustment, and the 5.2V supply is derived
from the -22V supply. It turns out that -20V/-22V*5.2V is ~4.7V, so the low
5.2V supply is likely down to the low -22V supply. Did you try adjusting
the -22V supply?

Siggi

On Thu, Feb 15, 2024 at 6:53?AM Frank Mashockie <fmashockie@...>
wrote:

@Harvey

Left the lab for the day, but I did check the voltage drop across that
resistor R624 0.33ohm. I can't recall what it was off the top of my head,
but I'll let you know tomorrow. I thoroughly tested both power supply
circuits on the SG503 and if there is an issue, it must be something
loading down the supplies like you suggest.

However, I injected ~5.2V into the unit with an external power supply - it
did not fix the display issue. No difference whatsoever. It may be that
these are the normal voltages for the unit when it is powered from a TM5000
series mainframe.

I'll be taking another look at it tomorrow! Grateful for any further
suggestions as well!

-Frank

-Frank

One thing to note about calibrating the sg503. If you are going for the
best accuracy you will need the special cable.

In general use this is not critical but it can have a 1 to 2% effect on the
pk to pk output. So for dial accuracy this is a just be aware of it. Using
a non special cable will not effect flatness which is good.

The special cable is 50 ohms 1% if I remember the spec correctly

Eric



On Fri, Feb 23, 2024, 12:52 PM Adam R. Maxwell via groups.io <amaxwell=
[email protected]> wrote:

On Fri, Feb 23, 2024 at 07:12 AM, Frank Mashockie wrote:

I'd still be curious to know what voltages are typical at the -22V and

5.2V

rails for this SG503 powered via a TM5000 (not TM500). Because I am

still

measuring ~4.7V at the 5.2V rail even with it working. If anyone would

be

willing to measure that and share with the group, I would appreciate it!
Could save someone else from going down the same rabbit hole that I did

(if in

fact this is normal).

Curious whether you scoped your 5.2V rail and checked the voltage drop
across
R624? My 5.2V test point is at 5.2V until things warm up for a minute or
two, and
then starts wandering from 4.7-4.9 or so on my DMMs. The scope shows a
square
wave on the 5V test point that I think is due to the current limiter
kicking in, but
which the DMM averages out.

When the voltage drop across R624 goes below 0.6V, I'm back up to 5.2V. My
plan now is to replace the hottest ICs on the board and see if I can get
the current
down closer to the level Albert Otten reported, as I can't find any shorts
or bad
transistors.

Mine currently has no oscillator output unless I replace Q300 with a 2k
pot, per
the Wizard Workshop suggestion, so I'm afraid I've killed Q190 or U225. I
soldered
the grounded stud on the back of Q190 to the wrong point, so that's my
next stop.

Congrats on fixing your SG503. This is the plugin from hell as far as I'm
concerned.

Adam

On Fri, Feb 23, 2024 at 07:12 AM, Frank Mashockie wrote:

I'd still be curious to know what voltages are typical at the -22V and 5.2V
rails for this SG503 powered via a TM5000 (not TM500). Because I am still
measuring ~4.7V at the 5.2V rail even with it working. If anyone would be
willing to measure that and share with the group, I would appreciate it!
Could save someone else from going down the same rabbit hole that I did (if in
fact this is normal).

Curious whether you scoped your 5.2V rail and checked the voltage drop across
R624? My 5.2V test point is at 5.2V until things warm up for a minute or two, and
then starts wandering from 4.7-4.9 or so on my DMMs. The scope shows a square
wave on the 5V test point that I think is due to the current limiter kicking in, but
which the DMM averages out.

When the voltage drop across R624 goes below 0.6V, I'm back up to 5.2V. My
plan now is to replace the hottest ICs on the board and see if I can get the current
down closer to the level Albert Otten reported, as I can't find any shorts or bad
transistors.

Mine currently has no oscillator output unless I replace Q300 with a 2k pot, per
the Wizard Workshop suggestion, so I'm afraid I've killed Q190 or U225. I soldered
the grounded stud on the back of Q190 to the wrong point, so that's my next stop.

Congrats on fixing your SG503. This is the plugin from hell as far as I'm concerned.

Adam

I received some replacement 7490s and now this SG503 is fixed! I had to really sit down and teach myself how the 7490 works. I know what counters do but never really learned how they work. I'm still learning electronics and teach myself through repair mostly. I love a repair like this one that teaches me a new concept. A bit different than your typical power supply issue - though I did spend a bit too much time on that before moving on to the actual problem.

I'd still be curious to know what voltages are typical at the -22V and 5.2V rails for this SG503 powered via a TM5000 (not TM500). Because I am still measuring ~4.7V at the 5.2V rail even with it working. If anyone would be willing to measure that and share with the group, I would appreciate it! Could save someone else from going down the same rabbit hole that I did (if in fact this is normal).

The 10Mhz setting is still a bit scratchy - it gets unleveled at this setting (likely due to bad contact). And there are a couple cosmetic things I need to finish. As well as calibration. But that is it for this guy!

Here's the vblog of the repair on my YT channel for anyone interested.


Now all I need is to fix my CG5011 and I will be able to calibrate scopes!

-Frank

.... analog computing concepts continue to be of use, ....into the future:

In a research article in Science (AAAS) , Feb. 23, 2024 :


Programming memristor arrays with arbitrarily high precision for analog computing

In Section Research Article | In-Memory Computing

Abstract:
" In-memory computing represents an effective method for modeling complex physical systems that are typically challenging for conventional computing architectures but has been hindered by issues such as reading noise and writing variability that restrict scalability, accuracy, and precision in high-performance computations. We propose and demonstrate a circuit architecture and programming protocol that converts the analog computing result to digital at the last step and enables low-precision analog devices to perform high-precision computing. We use a weighted sum of multiple devices to represent one number, in which subsequently programmed devices are used to compensate for preceding programming errors. With a memristor system-on-chip, we experimentally demonstrate high-precision solutions for multiple scientific computing tasks while maintaining a substantial power efficiency advantage over conventional digital approaches. " ...

and

" Many complex physical systems can be described by coupled nonlinear equations that must be analyzed simultaneously at multiple spatiotemporal scales. However, these systems are often too complicated for analytical techniques, and direct numerical computation is hindered by the “curse of dimensionality,” which requires exponentially increasing resources as the size of the problem increases. These systems range from nanoscale problems in material modeling to large-scale problems in climate science. Although the need for accurate and high-performance computing solutions is growing, traditional von Neumann computing architectures are reaching their limit in terms of speed, energy consumption, and infrastructure. " ...

I found a parts TDS380 and swapped the option 14 rear panel connectors over to my working TDS380. Nothing else needed to be done - the connections were recognized when I booted. Having the ability to connect it to an external monitor was a nice benefit as well. If you do that, though, you'll need to make an adapter for the VGA connector. The pinout is non-standard.

Hi everyone, I have a TDS 380 that I want to use with GPIB for control and plotting. I've given up on locating a TD3F14A kit to do the conversion on my scope. Can I obtain any TDS 310, 320, 330, 340, 360 with these parts and move them to my 380? Will my 380 firmware recognize the opt. 14 hardware?

Don

On Wed, Feb 21, 2024 at 08:28 PM, greenboxmaven wrote:

Although it was exceptionally basic, General Electric offered an analog
computer science kit in the early 1960s.

?? Bruce Gentry, KA2IVY

Ah, yes! The GE "Project: Analog Computer" kit. I had one of those. It was really just an electrified slide rule, using potentiometers instead of sliding rails.
Better was "Project: Shortwave Radio" a printed circuit board based kit to build a 5 transistor, 6-18MHz superheterodyne radio with headphone output. I loved that kit and modified it to cover down to 3.5MHz to listen to 80 meter ham radio. It even had a BFO for CW/SSB.
--John Gord

It is a nice design. I like the compactness of it. I just figured out the Step Gen output and External input "trick" this past week. I wonder if the Tek engineers had this multiplier in mind when they added those jacks? It sure makes it simpler to hook up an external multiplier.

I like the one I made based upon ChuckA's design (I admit I am biased : ) ) as I can leave it hooked in and select "0" multiplication (as well as 50). Though the one I built goes to "only" -150V. I also prefer a linear power supply over a switcher and a wall wart supply.

Dave

Although it was exceptionally basic, General Electric offered an analog computer science kit in the early 1960s.

?? Bruce Gentry, KA2IVY

Hi Miguel,

This is my latest design. It's been something I've wanted to build for my 576 for about a year so I could draw a complete set of characteristic curves for vacuum tubes with a large cutoff voltage. The ADHV4702-1 high voltage op amp makes it very straightforward to generate the necessary negative grid voltage to drive tubes to cutoff. Gain is fixed at 10x so any step adjustments are made directly on the curve tracer. The only trouble with the ADHV4702-1 is that it's a QFN package, so it's a bit of a pain to solder.

I'd be happy to hear any feedback, other features that might prove useful, or applications it would be appropriate for. The current design is pretty application specific and the layout of the banana jack interconnects are for easy mating to the 576 and 577. The +0/-200v output doesn't lend itself to many other applications, but it could prove useful in the right situation. It can happily output 20ma @ 200v continuously. I suppose it could be useful as a negative bias generator when breadboarding or repairing vacuum tube circuits...

-Chris

Some years ago there was an analogue computer on eBay being broken up. Consisted of twelve TM506 racks with six AM501s in each.

Neat solution.

EJP

Agree - I see several things I would be interested in but without pricing I'm just going to move on...

Very cool.

I didn't see the Heathkit analog computer on either website, though.

DaveD