Video Friday: Such a Showoff

High-Stability Film Resistor

All photographs by Eric Schlaepfer & Windell H. Oskay

This high-stability movie resistor, about 4 millimeters in diameter, is made in a lot the identical manner as its cheap carbon-film cousin, however with exacting precision. A ceramic rod is coated with a fantastic layer of resistive movie (skinny steel, steel oxide, or carbon) after which a wonderfully uniform helical groove is machined into the movie.

Instead of coating the resistor with an epoxy, it’s hermetically sealed in a lustrous little glass envelope. This makes the resistor extra sturdy, perfect for specialised instances similar to precision reference instrumentation, the place long-term stability of the resistor is essential. The glass envelope supplies higher isolation towards moisture and different environmental adjustments than customary coatings like epoxy.

15-Turn Trimmer Potentiometer

It takes 15 rotations of an adjustment screw to maneuver a 15-turn trimmer potentiometer from one finish of its resistive vary to the opposite. Circuits that should be adjusted with fantastic decision management use one of these trimmer pot as an alternative of the single-turn selection.

The resistive aspect on this trimmer is a strip of cermet—a composite of ceramic and steel—silk-screened on a white ceramic substrate. Screen-printed steel hyperlinks every finish of the strip to the connecting wires. It’s a flattened, linear model of the horseshoe-shaped resistive aspect in single-turn trimmers.

Turning the adjustment screw strikes a plastic slider alongside a observe. The wiper is a spring finger, a spring-loaded steel contact, hooked up to the slider. It makes contact between a steel strip and the chosen level on the strip of resistive movie.

Ceramic Disc Capacitor

Capacitors are elementary digital elements that retailer vitality within the type of static electrical energy. They’re utilized in numerous methods, together with for bulk vitality storage, to easy out digital alerts, and as pc reminiscence cells. The easiest capacitor consists of two parallel steel plates with a spot between them, however capacitors can take many types as long as there are two conductive surfaces, referred to as electrodes, separated by an insulator.

A ceramic disc capacitor is a low-cost capacitor that’s continuously present in home equipment and toys. Its insulator is a ceramic disc, and its two parallel plates are extraordinarily skinny steel coatings which are evaporated or sputtered onto the disc’s outer surfaces. Connecting wires are hooked up utilizing solder, and the entire meeting is dipped right into a porous coating materials that dries laborious and protects the capacitor from injury.

Film Capacitor

Film capacitors are continuously present in high-quality audio gear, similar to headphone amplifiers, report gamers, graphic equalizers, and radio tuners. Their key function is that the dielectric materials is a plastic movie, similar to polyester or polypropylene.

The steel electrodes of this movie capacitor are vacuum-deposited on the surfaces of lengthy strips of plastic movie. After the leads are hooked up, the movies are rolled up and dipped into an epoxy that binds the meeting collectively. Then the finished meeting is dipped in a troublesome outer coating and marked with its worth.

Other kinds of movie capacitors are made by stacking flat layers of metallized plastic movie, somewhat than rolling up layers of movie.

Dipped Tantalum Capacitor

At the core of this capacitor is a porous pellet of tantalum steel. The pellet is created from tantalum powder and sintered, or compressed at a excessive temperature, right into a dense, spongelike stable.

Just like a kitchen sponge, the ensuing pellet has a excessive floor space per unit quantity. The pellet is then anodized, creating an insulating oxide layer with an equally excessive floor space. This course of packs plenty of capacitance right into a compact machine, utilizing spongelike geometry somewhat than the stacked or rolled layers that almost all different capacitors use.

The machine’s optimistic terminal, or anode, is related on to the tantalum steel. The adverse terminal, or cathode, is fashioned by a skinny layer of conductive manganese dioxide coating the pellet.

Inductors are elementary digital elements that retailer vitality within the type of a magnetic subject. They’re used, for instance, in some kinds of energy provides to transform between voltages by alternately storing and releasing vitality. This energy-efficient design helps maximize the battery lifetime of cellphones and different transportable electronics.

Inductors usually include a coil of insulated wire wrapped round a core of magnetic materials like iron or ferrite, a ceramic full of iron oxide. Current flowing across the core produces a magnetic subject that acts as a form of flywheel for present, smoothing out adjustments within the present because it flows by way of the inductor.

This axial inductor has a lot of turns of varnished copper wire wrapped round a ferrite type and soldered to copper leads on its two ends. It has a number of layers of safety: a transparent varnish over the windings, a light-green coating across the solder joints, and a placing inexperienced outer coating to guard the entire part and supply a floor for the colourful stripes that point out its inductance worth.

Power Supply Transformer

This transformer has a number of units of windings and is utilized in an influence provide to create a number of output AC voltages from a single AC enter similar to a wall outlet.

The small wires nearer the middle are “high impedance” turns of magnet wire. These windings carry the next voltage however a decrease present. They’re protected by a number of layers of tape, a copper-foil electrostatic protect, and extra tape.

The outer “low impedance” windings are made with thicker insulated wire and fewer turns. They deal with a decrease voltage however the next present.

All of the windings are wrapped round a black plastic bobbin. Two items of ferrite ceramic are bonded collectively to type the magnetic core on the coronary heart of the transformer.