[HN Gopher] Reverse-engineering the Apollo spacecraft's FM radio
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Reverse-engineering the Apollo spacecraft's FM radio
Author : lycopodiopsida
Score : 62 points
Date : 2022-07-09 10:41 UTC (12 hours ago)
(HTM) web link (www.righto.com)
(TXT) w3m dump (www.righto.com)
| bilsbie wrote:
| Is this also the technology that allowed the president to have a
| real time phone call with astronauts on the moon?
| kens wrote:
| The module I looked at was in the Command Module, so Nixon's
| telephone call would have gone through slightly different
| hardware on the Lunar Module.
| bouvin wrote:
| If you ever wanted to use the sound of the Apollo transmissions
| creatively, the Lunar Module [1] is possibly the most niche of
| Eurorack modules.
|
| [1] https://ajhsynth.com/Lunar.html
| drunkonvinyl wrote:
| That is the coolest niche module I've ever seen. Looking for
| used ones on reverb now.
| rwmj wrote:
| Is it a surprise they didn't use PCBs? I thought by the 50s and
| 60s PCBs were an established technology.
| kens wrote:
| The Apollo hardware is a mixture of various technologies. Some
| pieces (like the Apollo Guidance Computer and the LVDC) used
| printed circuit boards. But point-to-point wiring was also very
| common. So PCBs existed but weren't dominant.
| davidwritesbugs wrote:
| I was also very puzzled by this, I've seen pin mounting before
| in very old equipment but as you say PCBs were in widespread
| use by the Apollo mission. Perhaps a conservative approach to
| technology, or did it have a cost/reliability implication?
| varjag wrote:
| No, they weren't quite an established technology by 1960. Also
| multi-layer PCBs weren't a thing, and two layers do not allow
| routing for the component density.
| kens wrote:
| The Apollo Guidance Computer and the LVDC used multi-layer
| printed circuit boards for the Apollo missions. I think the
| AGC was 7 layers and the LVDC 12.
| varjag wrote:
| I stand corrected. Was it one of the project innovations
| though? Can't seem to recall ever seeing that myself on
| commercial period hardware.
| kens wrote:
| IBM used multi-layer PCBs for the IBM System/360 (1964)
| so they were in use for some applications. But most
| electronics seemed to stick with two layers at most for a
| long time.
| klondike_ wrote:
| PCBs during this time period were very brittle and fragile. The
| board itself was prone to cracking under high heat and the
| traces could easily lift off the board. Not a good fit for the
| hot vacuum tube circuits of the era. Zenith and other
| manufacturers often advertised point-to-point wiring as a
| feature for reliability
| ninefathom wrote:
| Seconded. I've worked with PCBs of that vintage quite a bit-
| both recently and closer to their era. They are absurdly
| heavy and fragile by modern standards, and were very prone to
| having the traces lift off the boards, to the point of being
| notorious for sudden electrical shorts. If memory serves,
| that problem persisted at least through the 1980s. I'm sure
| there was a technological development of PCBs that eased the
| issue; somebody who knows more on that subject may be able to
| clarify.
| asmithmd1 wrote:
| Ultra premium guitar amps use point-to-point wiring:
|
| https://secureservercdn.net/50.62.89.49/34e.08c.myftpupload....
|
| This guitar amp wiring looks much better than the Apollo radio
| iasay wrote:
| They did. Just not in aerospace until the mid 1960s when decent
| quality fibreglass (FR4) boards were available. The previous
| SRBP and Bakelite boards were fragile and/or hygroscopic.
| jaytaylor wrote:
| Hygroscopic, an interesting new word to me! Thank you :)
|
| > _hy*gro*scop*ic_
|
| > adjective
|
| > (of a substance) tending to absorb moisture from the air.
| relating to humidity or its measurement.
| [deleted]
| zoomablemind wrote:
| Very methodical narration - pleasure to follow!
|
| I wonder if the reverse-engineered modules ended up functional,
| or the objective was only to determine the missing pin part.
|
| Was the silicone used to simply immobilize the mounted components
| or for other purposes like cooling, fire retardation?
| kens wrote:
| The objectives were curiosity (understanding how it works) and
| finding the missing pin so we can power up the module. The
| reverse-engineering isn't good enough to build a new one, e.g.
| I didn't figure out the capacitor values.
|
| I don't think the silicone had any other purpose than keeping
| the components in place.
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