Sperry Vertical Gyro

rpadula

rpadula

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PancakeBunny
Friend of mine at work sent me this EE Times link showing the inner workings of a 747's gyro. The amplifier board on page 2 looks like the inside of my Century I autopilot! :yikes:
 
tonycondon said:
well, they're about the same vintage arent they?
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I believe so. After having spent most of my engineering life dealing with digital circuits, I find it amazing that all that spaghetti works! Or, shall I say works the same way every time. :smile:
 
rpadula said:
I believe so. After having spent most of my engineering life dealing with digital circuits, I find it amazing that all that spaghetti works! Or, shall I say works the same way every time. :smile:
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That's the rub with analog electronics, it never really works the same way twice. Component drift, Johnson noise, device to device parametric variations, supply voltage changes, and temperature effects all conspire to change an analog circuit's behavior. With (most) digital circuitry behaviors can be virtually identical (whether correct or not) between examples and over time. Of course since most of our world exhibits continuous behavior (at least above the quantum level) there's always going to be some analog circuitry in anything that interfaces it.
 
gismo said:
That's the rub with analog electronics, it never really works the same way twice. Component drift, Johnson noise, device to device parametric variations, supply voltage changes, and temperature effects all conspire to change an analog circuit's behavior. With (most) digital circuitry behaviors can be virtually identical (whether correct or not) between examples and over time. Of course since most of our world exhibits continuous behavior (at least above the quantum level) there's always going to be some analog circuitry in anything that interfaces it.
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Johnson noise????? What the heck were long distance 747 pilots doing in the cockpit??????
 
gismo said:
That's the rub with analog electronics, it never really works the same way twice. Component drift, Johnson noise, device to device parametric variations, supply voltage changes, and temperature effects all conspire to change an analog circuit's behavior. With (most) digital circuitry behaviors can be virtually identical (whether correct or not) between examples and over time. Of course since most of our world exhibits continuous behavior (at least above the quantum level) there's always going to be some analog circuitry in anything that interfaces it.
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Yeah, and it's a talent that's being slowly lost, too. We see too many "cheap" designs that don't account for all of the tolerances. And then people wonder why they fail 6 months to a year down the road.

But I was much relieved when they taught us how to map the S-plane to the unit circle. :D
 
rpadula said:
Yeah, and it's a talent that's being slowly lost, too. We see too many "cheap" designs that don't account for all of the tolerances. And then people wonder why they fail 6 months to a year down the road.

But I was much relieved when they taught us how to map the S-plane to the unit circle. :D
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My very first commercially produced design failed miserably with about a 6 month MTBF. It was a replacement for a 30 second thermal timer packaged in a vacuum tube envelope. My version used an RC delay feeding a neon lamp optically coupled to a photoresistive device. Problem was the input was 120 volts AC which was rectified and filtered with an electrolytic cap. Unfortunately I used a 150 v rated cap and they all exploded eventually. My only excuse is I was still in high school at the time and although I thought I knew a lot about electronics, I still had a few things to learn.
 
Jeez Lance why didn't you just use a simple 555 timer :D:D:D
 
vontresc said:
Jeez Lance why didn't you just use a simple 555 timer :D:D:D
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Ah, 'cause this was 1968 and they hadn't been designed yet? Besides I needed 120 VAC input and an isolated normally open output. A 555 would require a supply but would have been far more accurate if they existed. IIRC the only integrated circuit I'd ever used or even seen at that point was just a pair of and gates in one (round) package.
 
gismo said:
My very first commercially produced design failed miserably with about a 6 month MTBF. It was a replacement for a 30 second thermal timer packaged in a vacuum tube envelope. My version used an RC delay feeding a neon lamp optically coupled to a photoresistive device. Problem was the input was 120 volts AC which was rectified and filtered with an electrolytic cap. Unfortunately I used a 150 v rated cap and they all exploded eventually. My only excuse is I was still in high school at the time and although I thought I knew a lot about electronics, I still had a few things to learn.
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The problem was in the Fetzer valve. Come on, I can't believe you don't know this!!!
 
gismo said:
My very first commercially produced design failed miserably with about a 6 month MTBF. It was a replacement for a 30 second thermal timer packaged in a vacuum tube envelope. My version used an RC delay feeding a neon lamp optically coupled to a photoresistive device. Problem was the input was 120 volts AC which was rectified and filtered with an electrolytic cap. Unfortunately I used a 150 v rated cap and they all exploded eventually. My only excuse is I was still in high school at the time and although I thought I knew a lot about electronics, I still had a few things to learn.
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I love posts like this--not very often--that I read something and comprehend almost nothing.
 
jesse said:
I love posts like this--not very often--that I read something and comprehend almost nothing.
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Yeah, but I'll bet you can relate to a high school kid who thinks he knows everything but doesn't even know how much he doesn't know.
 
gismo said:
Yeah, but I'll bet you can relate to a high school kid who thinks he knows everything but doesn't even know how much he doesn't know.
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I miss knowing everything. Sucks getting dumber every year. :)
 
Will any of this help me fix the Century IIIB in my Aztec? :)
 
jesse said:
I love posts like this--not very often--that I read something and comprehend almost nothing.
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Ha!

Perhaps the only time in my lifetime when I know more than Jesse. Of course, it's all obsolete, but still...
 
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