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Author here if anyone has questions about obscure Apollo hardware...

by kens 4y ago

mzs 4y ago
Do you have a guess? >The unusual feature of this module is the encapsulated module in the upper left. This module appears to contain three transistors and five capacitors. It's unclear why these components are encased in plastic. The block diagram for this module doesn't show any special circuitry that would motivate encapsulation. I hope to reverse-engineer this module to figure this out.
- jmole 4y ago
  temperature consistency across all the parts, probably. It's the reason things like discrete current sources use dual transistor packages: important transistor parameters track strongly with temperature, and if you want them to match, the temperatures need to be the same.
- atoav 4y ago
  I'd also say thermal coupling to ensure these components drift with some common average temperature. One thing where this would be done is e.g. an exponential converter or an antilog-amplifier, although there one would need only two transistors (one PNP and one NPN).
zw123456 4y ago
Fascinating as usual Ken, thank you. I am still absorbing the tech, but one thing that struck me in the very detailed photos (thanks for that) it does not appear that the components, resistors, capacitors etc. were soldered to the binding posts, it looks almost as if they were welded or fused? I am wondering if that was for reliability due to vibrations of launch ? oops never mind, i see your comment on one photo.
- kens 4y ago
  Yes, the components were spot-welded. This was common in the Apollo electronics. I think it was more reliable than soldering.
  - zw123456 4y ago
    Right, it had to survive the vibration of the mighty Saturn V. But even so, that construction, the insulating tubes and hot glue, I am not sure I would risk my life on that!
    - Koshkin 4y ago
      I am sure it (the construction) was extensively tested.
    - HPsquared 4y ago
      It's unlikely the astronauts would trust their life to this processor alone. There would be at least one backup, and probably a plan in the event of total communication failure. System design!
      - zw123456 4y ago
        Could be but just looking at the block diag Ken showed, that thing looked like a really critical component that all the comm ran through, although it looks like there may have been a way to bypass it for voice only comm in an emergency. But regardless, I still think those guys were amazingly brave, they knew the thing they were riding in was pretty cutting edge and there were big risks. (Apollo 13 of course is an example).
ThinkingGuy 4y ago
I was interested to see how communication between and from the individual astronauts was handled via VHF and then relayed by the lunar lander. Did the lunar rover used on Apollo 15-17 have the same equipment as the lunar lander, to transmit back to Earth?
- kens 4y ago
  The Lunar Communications Relay Unit (LCRU) on the rover provided S-band communication to Earth (MSFN) for voice, telemetry and TV.
urda 4y ago
What's your favorite bit of obscure Apollo hardware?
- kens 4y ago
  I like the traveling wave tube amplifier because it's such a wild way to amplify a signal. The digital ranging using a pseudorandom sequence is also pretty cool.
  - sponaugle 4y ago
    That article you did on the digital ranging was fantastic in part because once you read it, you think "Yea, that is a great way to do that, why didn't I think of that!". It was both novel and easy to appreciate.
AdamJacobMuller 4y ago
Thank you for all of your articles, they make hardware engineering understandable for someone like me who is a software engineer and burns himself every time he touches a soldering iron :) > The components are liberally covered in what looks like hot glue. I suspect that the hot glue was only used in equipment for ground testing, while modules for spaceflight were fully encapsulated to prevent short circuits. This is making me wonder, where in the world are you getting this stuff from?
- kens 4y ago
  A collector loaned us the premodulation processor. I think he got it from RR Auction, which regularly has auctions with lots of amazing space hardware.

Author here if anyone has questions about obscure Apollo hardware...

by kens 4y ago

Author here if anyone has questions about obscure Apollo hardware...

mzs 4y ago

Do you have a guess? >The unusual feature of this module is the encapsulated module in the upper left. This module appears to contain three transistors and five capacitors. It's unclear why these components are encased in plastic. The block diagram for this module doesn't show any special circuitry that would motivate encapsulation. I hope to reverse-engineer this module to figure this out.

jmole 4y ago
temperature consistency across all the parts, probably. It's the reason things like discrete current sources use dual transistor packages: important transistor parameters track strongly with temperature, and if you want them to match, the temperatures need to be the same.
atoav 4y ago
I'd also say thermal coupling to ensure these components drift with some common average temperature. One thing where this would be done is e.g. an exponential converter or an antilog-amplifier, although there one would need only two transistors (one PNP and one NPN).

zw123456 4y ago

Fascinating as usual Ken, thank you. I am still absorbing the tech, but one thing that struck me in the very detailed photos (thanks for that) it does not appear that the components, resistors, capacitors etc. were soldered to the binding posts, it looks almost as if they were welded or fused? I am wondering if that was for reliability due to vibrations of launch ? oops never mind, i see your comment on one photo.

kens 4y ago
Yes, the components were spot-welded. This was common in the Apollo electronics. I think it was more reliable than soldering.
- zw123456 4y ago
  Right, it had to survive the vibration of the mighty Saturn V. But even so, that construction, the insulating tubes and hot glue, I am not sure I would risk my life on that!
  - Koshkin 4y ago
    I am sure it (the construction) was extensively tested.
  - HPsquared 4y ago
    It's unlikely the astronauts would trust their life to this processor alone. There would be at least one backup, and probably a plan in the event of total communication failure. System design!
    - zw123456 4y ago
      Could be but just looking at the block diag Ken showed, that thing looked like a really critical component that all the comm ran through, although it looks like there may have been a way to bypass it for voice only comm in an emergency. But regardless, I still think those guys were amazingly brave, they knew the thing they were riding in was pretty cutting edge and there were big risks. (Apollo 13 of course is an example).

ThinkingGuy 4y ago

I was interested to see how communication between and from the individual astronauts was handled via VHF and then relayed by the lunar lander. Did the lunar rover used on Apollo 15-17 have the same equipment as the lunar lander, to transmit back to Earth?

kens 4y ago
The Lunar Communications Relay Unit (LCRU) on the rover provided S-band communication to Earth (MSFN) for voice, telemetry and TV.

urda 4y ago

What's your favorite bit of obscure Apollo hardware?

kens 4y ago
I like the traveling wave tube amplifier because it's such a wild way to amplify a signal. The digital ranging using a pseudorandom sequence is also pretty cool.
- sponaugle 4y ago
  That article you did on the digital ranging was fantastic in part because once you read it, you think "Yea, that is a great way to do that, why didn't I think of that!". It was both novel and easy to appreciate.

AdamJacobMuller 4y ago

Thank you for all of your articles, they make hardware engineering understandable for someone like me who is a software engineer and burns himself every time he touches a soldering iron :) > The components are liberally covered in what looks like hot glue. I suspect that the hot glue was only used in equipment for ground testing, while modules for spaceflight were fully encapsulated to prevent short circuits. This is making me wonder, where in the world are you getting this stuff from?

kens 4y ago
A collector loaned us the premodulation processor. I think he got it from RR Auction, which regularly has auctions with lots of amazing space hardware.