What exactly does a toroid do?

[Ouchyfoot]

What exactly does a toroid do, and what would happen if I replaced a small toroid with a larger one?

[ryansoh3]

An inductor resists changes in electric flow by storing energy magnetically. It smoothens fluctuating currents, and using a bigger inductor may or may not alter the circuit significantly. It’s used in buck and/or boost circuits to regulate voltage and current.

Here’s some excellent info by Le Quack at LPF:

Buck Regulator

A buck regulator is a switching step DOWN regulator. Most of these for our purposes are monolithic; they contain all needed parts inside of the IC package.

They step down voltage by using a switch, typically a MOSFET, a type of transistor. By rapidly turning the switch off and on, (as fast as 2 mhz!) they chop the DC supply up into something called a square wave.

The square wave is then fed into an inductor, which smooths it out into an average voltage of the square wave. It is then fed through a smoothing capacitor, which then smooths out the voltage even further, to essentially pure DC. Once it is fed through the capacitor, it goes through the current sense resistor, to the feedback op amp.

Feedback in a buck regulator works by modifying the duty cycle of the MOSFET. This means, that when the voltage across the current sense resistor is too high, (AKA too much current) the regulator will turn off for a little while to drop the output voltage a bit. If the voltage then becomes too low, the regulator will turn back on again, causing the voltage to then rise. This repeats again and again thousands of times a second to maintain regulation.

Buck regulators are only good if your laser diodes forward voltage is LOWER than your supply voltage. They can supply additional current with more supply voltage though!

How laser diode drivers work; An Explanatory Thread

[Dimbo_The_Blinky]

You mean besides oppose changes in current flow? It’s basically just a very-efficiently-made Inductor.

Hopefully this will generate some useful discussion!! It’s hard to answer, for some reason.

I’m grinding down the same trail, so I can maybe be some small help, but only as another traveler may remember a certain watering hole or cave along the way.

It’s funny, to me, how the answer that question is so-often a description of what it does, not how it does it. The physics interests me the most, but I’m weird that way. [/watering hole]

Sorry. What do you mean by “small” and “large”? Physical size isn’t a reliable indicator of performance, is why I ask…

Inductance (in Henries) of a Toroid is determined by the material of which it’s made (or not made, in an air-core inductor) and the number of wire turns taken around it. AFAIK, the smallest possible Inductor is a simple single turn of wire in the air.

Generally, higher (or “larger”) inductance results in a lower resonant frequency, in RF applications.

To finally answer your question, in a tuned resonant circuit, changing the Toroid to one with a different Inductance will probably just wreck it. Getting a different physical size with the same Inductance might change how much net current you could carry, but only through that component (not necessarily the rest of the circuit supporting it).

Sorry to wander. I hope to cull this post to its essence as this discussion takes off — hint, hint! (Time to hear from them what knows what to know!) :party: