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Space race PSUs

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Piotr Wyderski
Guest

Wed Feb 06, 2019 8:45 am   



Hi,

what PSUs did they use in the rockets/lunar modules back then in the
60s? Some early switchers or was everything linear?

Best regards, Piotr

Tim Williams
Guest

Wed Feb 06, 2019 8:45 am   



Yup!

High level overview of one system here:
https://www.ibiblio.org/apollo/Documents/ApolloTrainingElectricalPowerSystemStudyGuide.pdf

Enjoy this series -- they test the power supply in this one, but it's well
worth watching all of them.
https://www.youtube.com/watch?v=9Ys-VshuOLQ

Going back further, no idea, you'd have to find documentation on it, if it's
out there. Best case, someone's done a video series about it and there you
go; or it's on archive.org or something like that. Worst case, file a FOIA
regarding a particular mission and see what they have (or ask the e.g.
Library of Congress? where the docs are, if they're already public).

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

"Piotr Wyderski" <peter.pan_at_neverland.mil> wrote in message
news:q3e12k$s8v$1_at_node1.news.atman.pl...
Quote:
Hi,

what PSUs did they use in the rockets/lunar modules back then in the 60s?
Some early switchers or was everything linear?

Best regards, Piotr


Piotr Wyderski
Guest

Wed Feb 06, 2019 8:45 am   



Tim Williams wrote:

Great, thanks!

> Going back further, no idea, you'd have to find documentation on it

In the V rockets the Germans used magnetic amplifiers and hence
everything was based on AC -- but long-term operation wasn't exactly a
goal. ;-)

Best regards, Piotr

piglet
Guest

Wed Feb 06, 2019 4:45 pm   



On 06/02/2019 3:04 pm, piglet wrote:
Quote:
On 06/02/2019 7:07 am, Piotr Wyderski wrote:
Hi,

what PSUs did they use in the rockets/lunar modules back then in the
60s? Some early switchers or was everything linear?

     Best regards, Piotr


Here is the Apollo Guidance computer 28V to 4V buck switcher:

https://www.dropbox.com/s/w7haa1j14usb0xy/AGC_PSU4V_a30-a31-1.jpg?dl=0

I would love to know more about the earlier Gemini (IBM all descrete)
computer but there is much less info on the web than for Apollo. From
what little seen I suspect that had DC-DC transformer converter for the
logic supplies so kind-of switch mode too?

piglet


N.B. Here is the AGC power supply for the DSKY electroluminescent
display, HV AC square wave. Note the mag-amp:

https://www.dropbox.com/s/1veq869lng3s58b/AGC_PSU_ELHV_d7-el_power.jpg?dl=0

piglet

piglet
Guest

Wed Feb 06, 2019 4:45 pm   



On 06/02/2019 7:07 am, Piotr Wyderski wrote:
Quote:
Hi,

what PSUs did they use in the rockets/lunar modules back then in the
60s? Some early switchers or was everything linear?

    Best regards, Piotr


Here is the Apollo Guidance computer 28V to 4V buck switcher:

<https://www.dropbox.com/s/w7haa1j14usb0xy/AGC_PSU4V_a30-a31-1.jpg?dl=0>

I would love to know more about the earlier Gemini (IBM all descrete)
computer but there is much less info on the web than for Apollo. From
what little seen I suspect that had DC-DC transformer converter for the
logic supplies so kind-of switch mode too?

piglet

bitrex
Guest

Wed Feb 06, 2019 6:45 pm   



On 02/06/2019 11:50 AM, bitrex wrote:
Quote:
On 02/06/2019 10:04 AM, piglet wrote:
On 06/02/2019 7:07 am, Piotr Wyderski wrote:
Hi,

what PSUs did they use in the rockets/lunar modules back then in the
60s? Some early switchers or was everything linear?

     Best regards, Piotr


Here is the Apollo Guidance computer 28V to 4V buck switcher:

https://www.dropbox.com/s/w7haa1j14usb0xy/AGC_PSU4V_a30-a31-1.jpg?dl=0

The AGC and hence man's trip to the moon was made possible by
decent-quality PNP transistors for current sources.


Or more accurately, to make Sziklai pairs from

bitrex
Guest

Wed Feb 06, 2019 6:45 pm   



On 02/06/2019 10:04 AM, piglet wrote:
Quote:
On 06/02/2019 7:07 am, Piotr Wyderski wrote:
Hi,

what PSUs did they use in the rockets/lunar modules back then in the
60s? Some early switchers or was everything linear?

     Best regards, Piotr


Here is the Apollo Guidance computer 28V to 4V buck switcher:

https://www.dropbox.com/s/w7haa1j14usb0xy/AGC_PSU4V_a30-a31-1.jpg?dl=0


The AGC and hence man's trip to the moon was made possible by
decent-quality PNP transistors for current sources.

Much of that hysteric buck converter seems designed around having to use
an NPN for second gain stage amp Q2 in a way that would be considered
awkward today, probably because without it the diff amp wouldn't have
enough gain to perform well at the desired switching frequency

Quote:
I would love to know more about the earlier Gemini (IBM all descrete)
computer but there is much less info on the web than for Apollo. From
what little seen I suspect that had DC-DC transformer converter for the
logic supplies so kind-of switch mode too?

piglet


piglet
Guest

Wed Feb 06, 2019 7:45 pm   



On 06/02/2019 5:03 pm, bitrex wrote:
Quote:
On 02/06/2019 11:50 AM, bitrex wrote:
On 02/06/2019 10:04 AM, piglet wrote:
On 06/02/2019 7:07 am, Piotr Wyderski wrote:
Hi,

what PSUs did they use in the rockets/lunar modules back then in the
60s? Some early switchers or was everything linear?

     Best regards, Piotr


Here is the Apollo Guidance computer 28V to 4V buck switcher:

https://www.dropbox.com/s/w7haa1j14usb0xy/AGC_PSU4V_a30-a31-1.jpg?dl=0

The AGC and hence man's trip to the moon was made possible by
decent-quality PNP transistors for current sources.

Or more accurately, to make Sziklai pairs from


All the PNPs in that circuit are saturated switches.

They can't have been that great - needed three in parallel Q9 Q10 Q11 to
drive the NPN power switch.

piglet

Winfield Hill
Guest

Wed Feb 06, 2019 7:45 pm   



bitrex wrote...
Quote:

On 02/06/2019 10:04 AM, piglet wrote:
On 06/02/2019 7:07 am, Piotr Wyderski wrote:

what PSUs did they use in the rockets/lunar modules back
then in the 60s? Some early switchers or was everything linear?

Here is the Apollo Guidance computer 28V to 4V buck switcher:

https://www.dropbox.com/s/w7haa1j14usb0xy/AGC_PSU4V_a30-a31-1.jpg?dl=0

The AGC and hence man's trip to the moon was made possible by
decent-quality PNP transistors for current sources.


Not sure the selection was as limited as you suggest. Probably
the earliest that design was under consideration was about 1963.
We had lots of good parts by then. E.g., here's a story about
Fairchild's 2N1613, silicon planar NPN in TO-5 package, introduced
in 1960 at Wescon. By 1963 there were multiple second sources.
http://semiconductormuseum.com/PhotoGallery/PhotoGallery_2N1613.htm


--
Thanks,
- Win

bitrex
Guest

Wed Feb 06, 2019 9:45 pm   



On 02/06/2019 01:34 PM, Winfield Hill wrote:
Quote:
bitrex wrote...

On 02/06/2019 10:04 AM, piglet wrote:
On 06/02/2019 7:07 am, Piotr Wyderski wrote:

what PSUs did they use in the rockets/lunar modules back
then in the 60s? Some early switchers or was everything linear?

Here is the Apollo Guidance computer 28V to 4V buck switcher:

https://www.dropbox.com/s/w7haa1j14usb0xy/AGC_PSU4V_a30-a31-1.jpg?dl=0

The AGC and hence man's trip to the moon was made possible by
decent-quality PNP transistors for current sources.

Not sure the selection was as limited as you suggest. Probably
the earliest that design was under consideration was about 1963.
We had lots of good parts by then. E.g., here's a story about
Fairchild's 2N1613, silicon planar NPN in TO-5 package, introduced
in 1960 at Wescon. By 1963 there were multiple second sources.
http://semiconductormuseum.com/PhotoGallery/PhotoGallery_2N1613.htm



I was mistaken piglet is correct there aren't any PNP current sources in
that circuit.

I didn't start learning about analog design until ah, more recently so
it's an odd-looking circuit to my eyes, when I see solid state designs
from that era I guess my go-to is "I hear the PNPs sucked" like you have
to do weird stuff to shove an NPN in Q2s position, if you were designing
a simple high-gain diff amp today you'd likely use a current-source
loaded PNP and be done with it.

bitrex
Guest

Wed Feb 06, 2019 9:45 pm   



On 02/06/2019 01:02 PM, piglet wrote:
Quote:
On 06/02/2019 5:03 pm, bitrex wrote:
On 02/06/2019 11:50 AM, bitrex wrote:
On 02/06/2019 10:04 AM, piglet wrote:
On 06/02/2019 7:07 am, Piotr Wyderski wrote:
Hi,

what PSUs did they use in the rockets/lunar modules back then in
the 60s? Some early switchers or was everything linear?

     Best regards, Piotr


Here is the Apollo Guidance computer 28V to 4V buck switcher:

https://www.dropbox.com/s/w7haa1j14usb0xy/AGC_PSU4V_a30-a31-1.jpg?dl=0


The AGC and hence man's trip to the moon was made possible by
decent-quality PNP transistors for current sources.

Or more accurately, to make Sziklai pairs from

All the PNPs in that circuit are saturated switches.

They can't have been that great - needed three in parallel Q9 Q10 Q11 to
drive the NPN power switch.

piglet


Ya I had thought Q4 was acting as some sort of load for Q2, it's not I
neglected to notice C6 it's for sync-signal-injection of some kind.

I couldn't see initially how the diff amp works at all with Q2 connected
that way from a DC-bias perspective but the AC voltage swing at that
node will be small so I guess there's enough headroom.

Piotr Wyderski
Guest

Thu Feb 07, 2019 10:45 am   



piglet wrote:

> Here is the Apollo Guidance computer 28V to 4V buck switcher:

Thank you very much, piglet!

Best regards, Piotr

Piotr Wyderski
Guest

Sat Feb 09, 2019 9:45 pm   



Tim Williams wrote:

Quote:


The more I read it, the more amazed I am. E.g. the three phase
AC synthesis using 8 steering waveforms and a bunch of windings
connected in a crazy way. Not very unusual today, but a top
notch engineering back then. Thanks again!

Best regars, Piotr


Guest

Sat Feb 09, 2019 11:45 pm   



On Sat, 9 Feb 2019 21:22:48 +0100, Piotr Wyderski
<peter.pan_at_neverland.mil> wrote:

Quote:
Tim Williams wrote:

High level overview of one system here:
https://www.ibiblio.org/apollo/Documents/ApolloTrainingElectricalPowerSystemStudyGuide.pdf

The more I read it, the more amazed I am. E.g. the three phase
AC synthesis using 8 steering waveforms and a bunch of windings
connected in a crazy way. Not very unusual today, but a top
notch engineering back then. Thanks again!


Interesting design which cancels out low harmonics and high harmonics
are then easy to filter out.

Each unit delivers only 1.25 kW but weights 20 kg and are quite
bulky.Then there are three such units. Apparently there are some
critical AC loads that would justify the use AC aboard Apollo.

The 115/200 V 400 Hz is a standard aviation voltage, so apparently
some existing AC devices were used.

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