5 ms·

One way valves are basically diodes, but for fluids rather than electrons. You can also make logic gates out of just diodes (or one way valves). Imagine writin

One way valves are basically diodes, but for fluids rather than electrons. You can also make logic gates out of just diodes (or one way valves). Imagine writing software for a hydraulic computer!

mbell 8y ago
> One way valves are basically diodes, but for fluids rather than electrons. The analog of the fluid in that analogy is electric charge/current, not electrons which move in the other direction (which kinda breaks the analogy as a result).
- Sharlin 8y ago
  And also move really really slowly compared to the field. Their (net) movement is actually pretty irrelevant to the propagation of what we call electricity an sich.
- rossdavidh 8y ago
  However, I think it would have been quite difficult for me to get the concept of "holes" in semiconductor current, which are positively charged pseudo-particles created by the absence of electrons, if I hadn't been able to think of them as being like bubbles in a fluid. They go the opposite way of the fluid flow, and they are somewhat particle-like. So it's not a totally broken analogy, it does help to clarify some things.
  - mbell 8y ago
    I generally found the fluid analogy did more damage than good for a lot of people in EE school. A lot of people think of electricity as electrons zipping around a circuit at the speed of light due (at least in part) to the water analogy. Having to transition from that world to thinking in charge transfer and fields while electrons move around linearly at a snails pace if at all was very difficult for many people. I'd bet in a poll of the general public, most people think electrons fly around a circuit like water in a pipe, which is of course completely wrong. I guess it's debatable whether the inaccuracy matters or not. But in general, I prefer analogies that are simplifications and leave out details, rather than those that are completely ass backwards from reality.
    - neuralRiot 8y ago
      The way the analogy was explained to me when i was a student is that the conductor is a hose filled with water, when you open the valve the water comes out instantly at the other end because the "charge" is moving. It was never confusing to me.
      - jcims 8y ago
        I think anyone that has waited for hot water to get to the tap understands this. Pressure (voltage) transmits at the speed of sound (light). The speed of the particles through the medium, on the other hand, depends on many factors.
      - hexane360 8y ago
        This is the correct way. In the water analogy, the circuit is a closed system and components are completely filled with water at all times. For example, the capacitor is a filled sphere with a rubber divider. The total amount of charge/water is constant, but you can change how it is divided between the two plates by an applied voltage/pressure.
      - fjsolwmv 8y ago
        The analogy is valid and hydraulic circuits work. If people transfer their incorrect understanding of water to incorrect knowledge of electricity, that doesn't make the analogy bad.
      - mbell 8y ago
        I think the analogy can work, but needs to be carefully applied. This wasn't an analogy taught in my EE program, but one that is common in TV programming and provided by high school science teachers whom may not themselves understand the nuance so many came into the program with this understanding in place. Ultimately though, this concept was the breaking point for my EE class; It's when half the class dropped out to other majors. Not that I blame the analogy entirely for this, I think in general this is the point at which a lot of people lose connection with deeper sciences. It's the point where analogies to the physical world (matter) break down because we're now fundamentally talking about energy, which doesn't obey the rules all humans are accustom to. The world where we can't see it or relate it to our daily experiences but only talk about it through mathematics.
jetrink 8y ago
MONIAC [1] was an analog computer designed in 1949 that used water to model the national economy of the United Kingdom. 1. https://en.wikipedia.org/wiki/MONIAC https://en.wikipedia.org/wiki/MONIAC
- digi_owl 8y ago
  Made by an engineer turned economist from New Zealand no less. Sadly he is better know for a diagram he drew of an observation, the Phillips curve. I fear that much like this hydraulic model, Steve Keen's work is likely to be ignored or ridiculed by future economists while they fret over religious X diagrams.
  - fjsolwmv 8y ago
    Hydraulic models solve differential equations. They aren't bad , but modern computers are a much better computational environment.
  - dredmorbius 8y ago
    There's a fairly significant overlap between engineers and economists. Chemists and physicists also. Largely out of the economic mainstream, since the 20th century, sadly.
- hexane360 8y ago
  This was brilliantly parodied in Terry Pratchett's Making Money.
  - Declanomous 8y ago
    I got a Kindle for Christmas, and I've been reading through Discworld chronologically. I'm on Raising Steam right now, and I already feel like I'm going to have to reread the series with a list of references open. There were a lot of places where it was apparent there was a reference to something, but it was completely inaccessible as an American in his late 20's. At the same time, I almost feel like I shouldn't read the last book for a while, it's going to be really bittersweet.
defterGoose 8y ago
There was a post here on Fluidics a few weeks ago.
vertexFarm 8y ago
If you've ever wondered what powered the logic of a hydraulic transmission back in the olden days, it's essentially a hydraulic computer with all sorts of components which are analogous to diodes, transistors, even a pump-driven comparator to weigh input shaft speed and load against the output shaft to decide when to switch a gear. Do an image search for an automatic transmission valve body. It even looks like a big industrial circuit board. Some components are passive like a check valve, some are active like a valve which is operated by pressure from some other part of the circuit. Newer ones also have partial electronic control, with microcontroller-driven solenoids and actuators moving around valves to control hydraulic rams which finally engage or disengage clutches. But it all began with no electronics at all. Pretty neat trick if you ask me. I remember being a kid taking apart my first Ford transaxle and being amazed by the sheer complexity, almost to the point where it seems biological. My dad bought a really bad one for a couple bucks at a junkyard. We didn't need it to fix anything, he just wanted to feed my curiosity. It was a great parenting move. I recommend doing it yourself if you find a cheap busted one, just to get the ideas flowing.
zaarn 8y ago
I luckily don't have to imagine it. During an electric course in school for half a year where we learned all kinds of stuff like high voltage circuitry, we also learned pneumatic logic. Almost all electric components can be replicated in pneumatics; capacitors, resistors, transistors, diodes (including Zener diodes)... And from that you can form simple logics. One design we had to generate was to build a pneumatic gate which would open and close by pressing four buttons (two for each side of the gate) and light up a red, yellow or green light depending on whether or not the gate is moving (of course the lights use a pressure sensor). Of course nobody builds that because such a system would be expensive compared to a Attiny with a shift register and a few relays capable of doing the same.

One way valves are basically diodes, but for fluids rather than electrons. You can also make logic gates out of just diodes (or one way valves). Imagine writing software for a hydraulic computer!

mbell 8y ago

> One way valves are basically diodes, but for fluids rather than electrons. The analog of the fluid in that analogy is electric charge/current, not electrons which move in the other direction (which kinda breaks the analogy as a result).

Sharlin 8y ago
And also move really really slowly compared to the field. Their (net) movement is actually pretty irrelevant to the propagation of what we call electricity an sich.
rossdavidh 8y ago
However, I think it would have been quite difficult for me to get the concept of "holes" in semiconductor current, which are positively charged pseudo-particles created by the absence of electrons, if I hadn't been able to think of them as being like bubbles in a fluid. They go the opposite way of the fluid flow, and they are somewhat particle-like. So it's not a totally broken analogy, it does help to clarify some things.
- mbell 8y ago
  I generally found the fluid analogy did more damage than good for a lot of people in EE school. A lot of people think of electricity as electrons zipping around a circuit at the speed of light due (at least in part) to the water analogy. Having to transition from that world to thinking in charge transfer and fields while electrons move around linearly at a snails pace if at all was very difficult for many people. I'd bet in a poll of the general public, most people think electrons fly around a circuit like water in a pipe, which is of course completely wrong. I guess it's debatable whether the inaccuracy matters or not. But in general, I prefer analogies that are simplifications and leave out details, rather than those that are completely ass backwards from reality.
  - neuralRiot 8y ago
    The way the analogy was explained to me when i was a student is that the conductor is a hose filled with water, when you open the valve the water comes out instantly at the other end because the "charge" is moving. It was never confusing to me.
    - jcims 8y ago
      I think anyone that has waited for hot water to get to the tap understands this. Pressure (voltage) transmits at the speed of sound (light). The speed of the particles through the medium, on the other hand, depends on many factors.
    - hexane360 8y ago
      This is the correct way. In the water analogy, the circuit is a closed system and components are completely filled with water at all times. For example, the capacitor is a filled sphere with a rubber divider. The total amount of charge/water is constant, but you can change how it is divided between the two plates by an applied voltage/pressure.
    - fjsolwmv 8y ago
      The analogy is valid and hydraulic circuits work. If people transfer their incorrect understanding of water to incorrect knowledge of electricity, that doesn't make the analogy bad.
    - mbell 8y ago
      I think the analogy can work, but needs to be carefully applied. This wasn't an analogy taught in my EE program, but one that is common in TV programming and provided by high school science teachers whom may not themselves understand the nuance so many came into the program with this understanding in place. Ultimately though, this concept was the breaking point for my EE class; It's when half the class dropped out to other majors. Not that I blame the analogy entirely for this, I think in general this is the point at which a lot of people lose connection with deeper sciences. It's the point where analogies to the physical world (matter) break down because we're now fundamentally talking about energy, which doesn't obey the rules all humans are accustom to. The world where we can't see it or relate it to our daily experiences but only talk about it through mathematics.

jetrink 8y ago

MONIAC [1] was an analog computer designed in 1949 that used water to model the national economy of the United Kingdom. 1. https://en.wikipedia.org/wiki/MONIAC https://en.wikipedia.org/wiki/MONIAC

digi_owl 8y ago
Made by an engineer turned economist from New Zealand no less. Sadly he is better know for a diagram he drew of an observation, the Phillips curve. I fear that much like this hydraulic model, Steve Keen's work is likely to be ignored or ridiculed by future economists while they fret over religious X diagrams.
- fjsolwmv 8y ago
  Hydraulic models solve differential equations. They aren't bad , but modern computers are a much better computational environment.
- dredmorbius 8y ago
  There's a fairly significant overlap between engineers and economists. Chemists and physicists also. Largely out of the economic mainstream, since the 20th century, sadly.
hexane360 8y ago
This was brilliantly parodied in Terry Pratchett's Making Money.
- Declanomous 8y ago
  I got a Kindle for Christmas, and I've been reading through Discworld chronologically. I'm on Raising Steam right now, and I already feel like I'm going to have to reread the series with a list of references open. There were a lot of places where it was apparent there was a reference to something, but it was completely inaccessible as an American in his late 20's. At the same time, I almost feel like I shouldn't read the last book for a while, it's going to be really bittersweet.

defterGoose 8y ago

There was a post here on Fluidics a few weeks ago.

vertexFarm 8y ago

If you've ever wondered what powered the logic of a hydraulic transmission back in the olden days, it's essentially a hydraulic computer with all sorts of components which are analogous to diodes, transistors, even a pump-driven comparator to weigh input shaft speed and load against the output shaft to decide when to switch a gear. Do an image search for an automatic transmission valve body. It even looks like a big industrial circuit board. Some components are passive like a check valve, some are active like a valve which is operated by pressure from some other part of the circuit. Newer ones also have partial electronic control, with microcontroller-driven solenoids and actuators moving around valves to control hydraulic rams which finally engage or disengage clutches. But it all began with no electronics at all. Pretty neat trick if you ask me. I remember being a kid taking apart my first Ford transaxle and being amazed by the sheer complexity, almost to the point where it seems biological. My dad bought a really bad one for a couple bucks at a junkyard. We didn't need it to fix anything, he just wanted to feed my curiosity. It was a great parenting move. I recommend doing it yourself if you find a cheap busted one, just to get the ideas flowing.

zaarn 8y ago

I luckily don't have to imagine it. During an electric course in school for half a year where we learned all kinds of stuff like high voltage circuitry, we also learned pneumatic logic. Almost all electric components can be replicated in pneumatics; capacitors, resistors, transistors, diodes (including Zener diodes)... And from that you can form simple logics. One design we had to generate was to build a pneumatic gate which would open and close by pressing four buttons (two for each side of the gate) and light up a red, yellow or green light depending on whether or not the gate is moving (of course the lights use a pressure sensor). Of course nobody builds that because such a system would be expensive compared to a Attiny with a shift register and a few relays capable of doing the same.