Ask your question to Youtube, they have the answer for everything.

john

Nope, sorry. A standard transistor has a base, an emitter, and a collector. A FIELD EFFECT TRANSISTOR, or FET, MOSFET, etc., has a source, a gate, and a drain. Get the terminology right.

Not electricity or power or voltage flowing. Current flows by passing electrons from one atom to the next due to a voltage potential. Then there's diodes.

I'm curious what a "standard" transistor is? Do you mean a BJT transistor? There is nothing standard about it. MOSFETS are the most widely used so if anything that would be the standard. For being so rude in your response, your own terminology is rather vague. The OP has a valid question and the type of transistor he is asking about is implied by his terminology. Everyone knows what he is asking.

To the OP, the answer is rather complicated. In the simplest explanation, the voltage applied to the gate either attracts electrons or electron holes (depending on the voltage and type of transistor) in a region connecting the source and drain. This accumulation of free electrons or electron holes then provide a path for current to flow between the source and drain. Kind of like an electrical draw bridge that is controlled by voltage at the gate. This is obviously a hand wavy answer. If you want a more detailed (and physics and math based) answer check out the transistor Wikipedia page or YouTube like another poster suggested.

For the gate to work one must do the truffle shuffle first.

Expanding on blackthorne- they consist of sandwiched layers of Silicon that are doped With electrons or electron holes. Thus you get pnp or npn type transistors -n standing for negative (doped with electrons) and p for positive (absence of e-). Without voltage change at the gate, No electrons (current) will thru the sandwiched layers. Of course a high enough voltage difference applied at the ends of the sandwich will break down that middle region and destroy the transistors functionality (blown transistors usually just conduct, or are always on).

Anyway, the gate pin acts on the middle layer - putting potential there which pulls Or pushes electrons depending on type.. one operates with a gate going low and the other with the gate going high (applying + voltage). Holes open up and electrons can flow, essentially. This allows current to flow thru the device from one end layer to the other, if there’s a difference in voltage potential between the two.

That’s your MOSFET- with the caveat that I learned this over 10 years ago so maybe missing details.. but running thru equations and such, it’s a whole college course on electron drift, and how circuit devices operate. I’m not as good with BJTs but it’s similar as I understand it.

I think the OP might be asking how does a potential difference exist at the gate of the FET since there is no apparent place for current to flow. With the caveat that I haven't been anywhere near a course on this stuff in 30+ years, [nevermind, I just looked into FETs more closely, and my understanding was incorrect]

With a bipolar transistor (I'm on more familiar ground here), s small amount of current applied to the base-collector pair of pins allows a much larger amount of current to flow from the emitter to the collector (at least for NPN transistors). At least that's what I remember from the rudimentary electronics I learned in high school.

I now know that the gate, source and drain of a FET are roughly equivalent to the base, emitter, and collector of a BJT (thanks wikipedia).

At the 100,000 foot view, and relating this to pinball hardware, all of these devices tend to be used to allow a small control signal to create higher level current flow to interact with the mechanical world. They tend to be the semiconductor hardware interfaces between logic and action. So the software on the CPU boards interacts with the playfield by sensing contact closures, and then creates actions (usually lights or coils) based on those senses and the rules of the game. These devices themselves have gotten more efficient over the past 50 years, and the amount of power they can handle has increased and the amount of heat dissappated has decreased by using new semiconductor materials and configurations, but they are still electronically controlled switches in the pinball application. (Note there is a whole slew of analog usages for these kinds of devices where the control signals are not just ON and OFF, but instead a range of analog signals, like voice or music)

This has much to do with the type of transistor, and the arrangement of the circuit. One way to do it is by using a PNP transistor in this arrangement. Applying voltage to the base of the transistor in question (i.e., "applying voltage to a single pin") stops current flowing from Vcc to ground. That is why this circuit is called active low.

So, applying the voltage to this point stops work from happening.

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Actually, nothing "moves" inside a transistor in the practical sense. At the atomic level, charge is being transferred, but nothing is moving. Magnetic movement based on current would be a relay (which was used for switching before transistors).

Voltage isn't being applied to a point. All transistors have some current flow from the gate (or base) to either the drain (collector), the source (emitter), or if available the body (substrate). The actual configuration of the current flow is based on the circuit, application, and particular type of transistor used.

It could be my interpretation, but I don't think the op is asking about what is happening at the atomic level. It seems to me that he is asking about applying voltage to a single point (a pin) and the gate closes (circuit shuts off) as a result.

....but, we haven't heard comments back from the op if any of these answers are helpful.

I feel like a number of responses here have essentially answered the OP question, hopefully. Applying a voltage to the gate pin controls a potential difference between the substrate layers so magic can happen, as long as the smoke inside hasn’t been released. The voltage doesn’t ‘go’ anywhere. Some leakage current occurs, as a ‘byproduct’, not by design.

I guess I'll throw my hat in the ring.

The simple answer is the voltage on the gate of the FET creates a charge. It's this charge that turns the transistor on or off. No gate current is needed for this action to occur. Since no current flows through the gate the gate doesn't draw any power, as power requires both voltage and current (P=VxI).

Kind of like if you put a charge on a balloon by rubbing it on your head, your hair will move towards the balloon without any current flowing between your hair and the balloon (no power required).

A bipolar transistor (base, emitter, collector) is functionally similar to a FET, but it's base does require current flow and it's internal operation is very different than the FET.

One thing to keep in mind. If a voltage is applied it has to be referenced to some point. If the low side isn't specified then it's implied to be ground (or the lowest potential in the circuit).

Think of a battery. If you only connect the (+) terminal and leave the (-) terminal floating, the battery won't do anything.

In the case of an n-channel MOSFET, the connection on the source acts as the low (-) potential and would provide the current ('ground') path you're looking for. Even though the MOSFET gate doesn't require any current to operate, it still needs the voltage (potential, charge) difference between the gate and the source to turn on.

In electronics, I think it's helpful to understand that the components don't know what "ground" means, their operation is only based on the potential differences between their connections.

Don't know if this makes things clearer or more confusing.