# Ram pump vs boost converter

Discussion in 'General Electronics Chat' started by kubeek, Jun 16, 2016.

1. ### kubeek Thread Starter AAC Fanatic!

Sep 20, 2005
4,875
863
We have all seen the analogy between flow of water and electricity, pressure, flow and restriction being equivalent to voltage, current, and resistance. Yesterday I found an example of a water circuit with an inductor and a capacitor, which performs equivalently to a boost converter. It´s called a ram pump, and it uses the kinetic energy of water flowing downstream to create slow flow of high pressure water.

See this video for explanation how it works.

Now tell my that the water analogy is wrong and should not be used to show how electricity works

endolith likes this.
2. ### nsaspook AAC Fanatic!

Aug 27, 2009
3,638
3,769
Because electrons don't carry the kinetic energy of a circuit normally. The energy is stored in fields (inductor and a capacitor) outside the conductors. What's the water analogy for that?

3. ### kubeek Thread Starter AAC Fanatic!

Sep 20, 2005
4,875
863
Well yes, you can´t model the efect of magnetic or dielectric materials with water, but for the basic ideal elements you can find their ideal water analogs and build circuits that behave the same and are subject to the same differential equations (except for some constants).

As for the fields, magnetic field is analog to kinetic energy, and electric field analog to pressue. Don´t you see how that pump behaves exactly like a boost converter, except that the mechanics of the first valve allow it to have a self contained oscillator and make it so that the system is virtually a current controled boost converter, with the inductor being the head pipe and the output capacitor being the tank?

Last edited: Jun 16, 2016
endolith likes this.
4. ### nsaspook AAC Fanatic!

Aug 27, 2009
3,638
3,769
In that same amount of time you could have explained the electrical equations directly with simple models of real circuits instead of a two step process that's prone to misinterpretation. IMO it's better to have initial confusion on the correct model than certainty on the analogy in the long run.

5. ### kubeek Thread Starter AAC Fanatic!

Sep 20, 2005
4,875
863
Yes you could, but there are people how will understand the relationships easier when you present them with a very similar situation, but one where they can relate to the world they already know.

endolith likes this.
6. ### nsaspook AAC Fanatic!

Aug 27, 2009
3,638
3,769
That, my friend is a large leap of faith.

7. ### #12 Expert

Nov 30, 2010
17,899
9,319
This analogy works for me. The mass of water flowing down from right to left exchanges potential energy for kinetic energy. That resembles the magnetic field around an inductor. In both cases, an attempt to suddenly stop the flow results in diverting the kinetic or magnetic energy to a different output. Why not just go to the calculus of it? Because a lot of people aren't that educated.

In several cases, I have used electronic principles to do mechanical jobs. I modeled the water supply system for a home as a bunch of resistors and it worked. I know how to pipe a home so that flushing the toilet will not change the temperature in the shower. My nephew needed to use an air tool on the end of 100 ft of 1/4 inch tubing. NFL! I placed a 5 gallon "capacitor" on the end of the 100 ft tube and he was able to do the job with a 6 ft hose from the air tank to the air tool. Pneumatics, hydraulics, and electronics have some similarities. Do the intake manifold and exhaust headers on a car engine resemble capacitors and inductors? Yes! If you model them correctly, you can arrive at tuned induction and tuned exhaust for certain RPM ranges.

endolith and kubeek like this.
8. ### nsaspook AAC Fanatic!

Aug 27, 2009
3,638
3,769
We try to reduce all problems to mechanical principles. After you understand electronics and hydraulics, analogy is great for understanding a problem without a lot of math. I just don't think it's that great method for learning electronics when it's been proven most students have little experience with real fluid systems.

https://www.lhup.edu/~dsimanek/scenario/analogy.htm

Last edited: Jun 16, 2016
9. ### #12 Expert

Nov 30, 2010
17,899
9,319
One of the strengths of this site is the different ways people model and explain real processes. Mine is one, yours is one. Sometimes I fail to communicate with the TS and somebody else succeeds. This is not a problem as long as nobody leads the TS down a fantasy path which results in a wrong conclusion. Simple models for simple people, straight up Calculus for the more educated. Especially in the Homework section, I find people that can speak Calculus and simple models bounce off them like water off a duck. In the Chat section, we find people with much lower levels of education, and simple models work better for them. It's about finding the level of the TS. If the simple model works, we can pursue the details, interactions, and exceptions later.

endolith likes this.
10. ### nsaspook AAC Fanatic!

Aug 27, 2009
3,638
3,769
100% concur with simple models of electricity (or any subject) for problems but frankly I see little use in developing simple or detailed physical analogies for teaching detailed facts about anything.