Circuit is to plumbing

Thread Starter


Joined Nov 29, 2011
Hello. I am as green as it gets in regards to electronics. However, I am a musician and I would like to start building effects pedals for guitars; just simple stuff like boosters or distortion pedals.

At first you might think, “This guy is lazy, there are tons of how to’s and guides on that sort of thing.” Well you are only half right. The how to build directions and other related topics usually just tell you, “Get this many of this type of resistor and put them here, here, and here.”
I want a simple understanding of what these various components do, not just to be told to put them here and carefully solder.

The most common electrical components I can find that are used in effects pedals, other than circuit boards, are


Now, even though I do not have any understanding of electronics, I do have a pretty good understanding of simple plumbing. I imagine that if the electronic components can be related to an equivalent plumbing component, I would have the initial understanding necessary to start with some trial and error self-teaching.

So for instance, if I understand potentiometers correctly, the pots are like ball-valves. As you turn a ball valve closed, the water flow decreases in proportion to how much the valve is turned. Therefore, as you turn a pot closed, the electrical flow decreases. Pots also have something to do with the wattage, and I think they are actually a specific type of resistor. Whereas the little tan and striped resistors are some sort of pinch in the plumbing. (please correct if wrong)

Is there anybody out there with the knowledge of both electronics and plumbing that can fill me in on what the list above relates to in the water world?

Or do you know of a readily available resource that does something similar?
(A Google search turned up surprisingly little.)
(Also, for this forums snotty folks, bring on the hate and disdain for my lack of effective research skills and ignorance of the complexities of explaining such wonderful thing that is basic electronics, just include something useful with it.)


Joined Oct 15, 2009
There are a few very basic plumbing/electronics analogies but your best bet to learn is to simply read through the chapters located at the top of this site (see where it says VOL 1. DC,etc...) Takes a few hours at most and you should have a MUCH better understanding of electronic components/uses.


Joined Oct 2, 2009
So for instance, if I understand potentiometers correctly, the pots are like ball-valves. As you turn a ball valve closed, the water flow decreases in proportion to how much the valve is turned. Therefore, as you turn a pot closed, the electrical flow decreases. Pots also have something to do with the wattage, and I think they are actually a specific type of resistor. Whereas the little tan and striped resistors are some sort of pinch in the plumbing. (please correct if wrong)
One can only carry an analogy so far, but here goes anyway.

No, a potentiometer is not a ball-valve.

Let's begin with basics.

A battery is a water pump.

A resistor is your piping. If you use a fat pipe, there is less resistance and more water will flow. A skinny pipe and it will restrict the water flow.

A capacitor is a water tank, like a reservoir. It can hold water. You can smooth out the flow of water by using a holding tank.

An inductor is a water impeller or turbine. When you get the water going, it wants to keep going until the turbine slows down. It stores kinetic energy.

A diode is a back-stop valve, like the ones you put on your garden hose faucet to stop the sun from forcing water from the garden hose back into the pipe. Water can only flow one way, not backwards. A rectifier is another name for a diode.

A switch is your stop valve, faucet, cockstop, what ever you call it. But NOTE the backwards terminology: When you CLOSE a switch current flows. When you OPEN a valve, water flows.

A potentiometer is a 2-way diverter valve. Water comes in one pipe and you can divert the water two ways. How much you divert depends on how much you turn the control knob. Turn it all the way to the left and 100% goes one way. Turn it all the way to the right and 100% goes the other way. Turn it halfway and 50% goes one way and 50% goes the other way.

A transistor is a power diverter valve. Instead of using manual power to control the diverter you can use electrical, pressure, pneumatic or hydraulic to control the setting of the valve.

How's that for starters. I'll come up with some more later.
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Joined Oct 2, 2009
An ammeter is a water flow meter.

A voltmeter is a pressure meter.

An op-amp is a complex control system that takes the pressure reading from the pressure meter and feeds it back to the power valve so that the pressure is always constant. You can call it a pressure balancing system. If the pressure fluctuates too much, you need to put a capacitor on the line (a pressure holding tank).


Joined Oct 2, 2009
When we design power supplies, we install small capacitors to take care of little fluctuations in the supply voltage. We call these filter capacitors, bypass or decoupling capacitors.

In plumbing, this is a water hammer, that little stub of piping that is filled with air and goes nowhere. When a valve is turned on and off quickly, the trapped air dampens the water pressure and minimizes the hydraulic shock or knock.


Joined Jul 17, 2007
Resistors generate electrical noise, like a hose nozzle generates audible noise.

As the current flows through the resistor, voltage is dropped across the resistor.

As water flows through a hose nozzle, the pressure in the hose is still high, but the pressure outside the hose is at atmospheric pressure (relatively low).

To reduce the noise at a resistor, we can use a capacitor.

To reduce the noise of a hose nozzle, we can throw it in a bucket of water.

Side note - metal film resistors generate much less noise, and are more accurate/stable than carbon resistors.
Carbon film resistors (they look like miniature dumbbells) are reasonably stable, but can change values on you with excessive heat, particularly when soldering.
Carbon resistors (cylindrical bodies) should be avoided, as they can/do change values very significantly over time and temperature.


Joined Mar 14, 2008
To elaborate a bit on the water analogy:

A discrete resistor is like a small orifice in the pipe. The smaller the orifice, the higher the resistance.

A capacitor is like a tank (size is capacitance) with a flexible membrane sealing the tank across the middle and outlets on both sides of the tank. The more pressure you apply and the larger the tank, the more water (charge) will be transferred from one side of tank to the other.

An inductor can be viewed as the inertia (inductance) of a heavy slug that fits snugly in the pipe with no leakage past it but it can readily move without friction. The ball takes effort to get it moving, and once it's moving it tends to keep moving. The heavier the slug the more inertia (inductance).


Joined Oct 2, 2009

Remember, all the piping in your circuit is the resistance. The more piping you have the more resistance there is. If there is too much resistance your flow will decrease. To increase the flow you have to apply more pressure, i.e. get a bigger pump.

Resistors in Series

In an electrical circuit, the current has to return back to the battery. Imagine a closed loop plumbing system like a central hot water heating system. If all the piping creates one long run with radiators all along the way, we call this a series circuit.

Resistors in Parallel

Instead of a series circuit, we can have hot water radiators branching off from the main line and then returning back to the pump. We call this a parallel circuit.

In the series circuit, more radiators will add resistance and hence will reduce the flow.

When we add more pipes in parallel we increase the net flow, that is, more current will flow.


Joined Dec 26, 2010
It is always necessary to remember that analogies only go so far. For instance, we can describe a transistor as a controlled valve.
I can't imagine however explaining the nuances of say the non-linear performance of an OC44 germanium transistor for an effects pedal, versus those of a 2N2905 silicon device. By the way, some people would assert that it is debatable that these can be proven even with proper electronic theory, but at least this gives us the means to examine the issues.

Transistors also come in other major classifications: PNP and NPN junction types, which conduct in opposite senses, similarly P and N channel field effect transistors, of both junction and insulated gate varieties, the latter divided into enhancement and (rare) depletion types. We get all of that without even beginning to encroach on the vast territory that is Integrated Circuits.

Beyond this, instead of transistors, some guitar amplifiers use electron tubes, which themselves divide into diodes, triodes, (beam) tetrodes, pentodes... None of this would seem to be addressable by"drain pipe" theory.

The point of this is not to say that the hydraulic analogy is not useful, but if you really want to understand musical equipment, you will really have to go beyond it before very long.


Joined Jun 7, 2009
You will find some very interesting applications in fluid control circuits, more so in oil based 'hydraulics' than in water 'plumbing'. Both pnuematic and hydraulic 'logic' were hotly persued by most major suppliers prior to electronics invading instrumentation and controls. Water 'plumbing' as an analogy, represents a very small subset of electrical qualities. Don't let that limitation impede your quest for knowledge. Call me snooty, but it's what I found through personal experience.