SD2000 Installing a better FET

[JC1]

Math or Execution

Hi Max,

You sure this was the fault of the math.

Or Man's execution of logistics.

No fly by wire in 69.

Oh that was fly by wire, just no auto pilot.

That was the fault of the Math?

No Sorry,

Open an engineering/technical book sometime.

See all those funny symbols.

That is math.

And until you get a hold on all that you got a hold on

nothing.

[Max]

Hi Max,

You sure this was the fault of the math.

Or Man's execution of logistics.

No fly by wire in 69.

Oh that was fly by wire, just no auto pilot.

That was the fault of the Math?

No Sorry,

Open an engineering/technical book sometime.

See all those funny symbols.

That is math.

And until you get a hold on all that you got a hold on

nothing.

Hi,
yes math is useful... but that time only Armstrong's eyes saved their butt.

LEM mounted a shoe-box size computer... and used the "Luminary" program version "99".

Problem was on power-supply-units but next Apollo-missions used different version of the Luminary , till last version, the 299.

read...
"Such frightening alarms occurred during the Apollo 11 landing (first moon
landing). If you listen to recordings of the landing, you will hear the Capcom
say "1201 alarm" and "1202 alarm." The astronauts' checklist had erroneously
called for the astronauts to turn on the rendezvous radar before initiation of
the descent. Subsequently, the program that managed the radar began demanding
too much of the computer's spare margin of time. The power supply for the radar
was not properly synchronized with the LM's main power supply. Consequently, as
the two power supplies went in and out of synchronization, the rendezvous radar
generated many spurious input signals to the LM's computer. In responding to
these signals, the computer delayed some of its guidance calculations and left
others unfinished. This situation caused the computer to issue alarms during
the landing. During a normal descent, the guidance program, which brought the
LM to its target landing site using a minimum of fuel, would issue commands
once every two seconds. Steering commands to the digital autopilot, which kept
the LM stable, were issued every 10th of a second. Although the landing, which
had an 11-minute guidance phase, was successful, a full minute's worth of
guidance commands were never issued by the computer due to rendezvous radar!


For debugging, the programmers at MIT had an IBM 360 model 175 mainframe
computer that acted as a simulator of the LM. Allan and his colleagues would
test their software in this simulator, which interfaced with their software
just as the real LM, with its associated dynamics, would. The IBM 360 produced
printed output as well as plots of the trajectories of the simulated landings.
In the real LM, the on-board computer had a digital display and a keyboard.
During landing, the computer would display a number, updated periodically. The
LM "Pilot", who was on the right and never touched the controls, would
continuously read out updated values of this number. The Commander on the left,
who was actually manipulating the controls, would find this number on a
reticule painted on the window. The target landing spot, where the computer was
trying to land, would be visible at that location out the window.
"

So also your assertion of "No fly by wire in 69." is not exact for the Apollo11/LEM that actually had a kind of fly-by-wire system!

Was math the problem ? Of course not. Math is really useful... but you miss the point that I focused on previous post: when you are in a hurry and things get complex... math couldn't save your butt... but experience can do.

I open tech-books quite often... and know the funny symbols you said but not for this I belive math is the answer for any technical problem!

Best regards,
Max

[JC1]

Hord to understand

Hi Max,

No fly by wire in 69.

Oh that was fly by wire, just no auto pilot.


I said they did have fly by wire.

just no auto pilot. I think they did well.

But none of this has anything to do with math.

This all has to do with implementation.

Now they didn't have anyone to "copy".

Original thought.

Experience in what? Trial and Error. Lots of trials.

Lots of errors. Did alot of that when I was young.

Wasted alot of time. Got very little real progress.

Not to say I don't still make alot of errors, I do.

Just at a higher level.

Anyway the Old NE5534A is still the standard by which

others are compared, and the others are still a struggling.

But then they aren't designing them to be fast on

recovery. Perhaps someone could design a discrete

design that would. then might have a "better" all the way

around front end.

[eclipse]

So is it a good idea to change that FET with new, having higher capacitance, risking melting everything around , and which one turns to be best replacement?

[eclipse]

I noticed one very big resistor in the supply part, probably 1 or 2 Watt.
Does anybody know it's exact value?

[robby_h]

So is it a good idea to change that FET with new, having higher capacitance, risking melting everything around , and which one turns to be best replacement?

Be wary of some of these older threads. The IRF710 is simply part of a high voltage clamp circuit and spends it's life operating as a variable high value resistor. It doesn't switch the coil and there's no benefit what so ever in replacing it.

[ZED]

Choke ol`boy

Eclipse the component you refer to is actually a inductor commonly refered to as a choke,you will see it in the SD2000 schematics on the "transmit" page,its value is 1.1 mh.

Zed

[barry]

Woody what fet did you end up using ?

[Unregistered]

The best fets to use are ST50W20NK They are the same fets that arte used in the GP series. Even change the reservoir FET, Change all 3 as if you drop the pulse frequency the resevoir stabilisation Fet will get very hot.

http://detectormods.com