{"id":1147,"date":"2026-07-31T17:02:29","date_gmt":"2026-07-31T15:02:29","guid":{"rendered":"https:\/\/www.i8zse.it\/en\/?page_id=1147"},"modified":"2026-07-31T17:03:13","modified_gmt":"2026-07-31T15:03:13","slug":"passive-components","status":"publish","type":"page","link":"https:\/\/www.i8zse.it\/en\/pixie\/passive-components\/","title":{"rendered":"Passive components"},"content":{"rendered":"

Before examining the Pixie schematic, it is necessary to be able to recognize, at a glance, the components we will find in the kit. Let us start with passive components<\/strong>: elements that do not amplify or generate energy, but store it, dissipate it, or control its flow.<\/p>\n

The resistor<\/h2>\n

\"\"<\/a><\/p>\n

The resistor is a component that opposes the flow of current. It has virtually endless applications in electronics because resistance, voltage and current are closely related through Ohm’s law<\/strong>.<\/p>\n

\"\"<\/p>\n

Ohm’s law relates the three fundamental quantities of a circuit (voltage E, current I, resistance R) through a set of formulas that allow one quantity to be calculated when the other two are known. It is the most widely used calculation tool when designing or testing an electronic circuit. Combined with the formulas for power P, it also allows this quantity to be calculated, providing one of the most important tools in electronics.<\/p>\n

\"\"<\/a><\/p>\n

There are many different types of resistors, depending on the power they need to dissipate, the required precision and the manufacturing technology. Trimmers<\/strong> and potentiometers<\/strong> are essentially variable resistors: their resistance can be manually adjusted by moving a slider. It should be remembered that, like all real components, resistors are never completely pure<\/em>: they also exhibit, to a small extent, parasitic capacitive and inductive characteristics. This aspect is normally negligible at low frequencies, but becomes important when working with radio frequencies.<\/p>\n

The colour code<\/h3>\n

Through-hole resistors do not show their value using numbers, but rather through a series of coloured bands printed on their body. Each colour corresponds to a digit, and the sequence of bands encodes the resistance value in ohms and the tolerance.<\/p>\n

\"\"<\/p>\n

Learning how to read this code is one of the first practical skills to acquire: with some practice it becomes immediate, but at the beginning it is always advisable to verify the value with a multimeter, especially when you are just starting out.<\/p>\n

The capacitor<\/h2>\n

\"\"<\/a><\/p>\n

The capacitor is a passive component that stores a small amount of energy in an electric field<\/strong>. It is made of two conductive layers separated by an insulating material called a dielectric<\/strong>.<\/p>\n

\"\"<\/p>\n

This insulating layer prevents the flow of direct current once the charge is complete: in steady-state DC conditions, a capacitor behaves like an open circuit. Its main characteristic, capacitance<\/strong>, expresses the amount of energy it can store and is measured in Farads<\/strong> \u2014 although, as seen on the previous page, in practice the submultiples (\u00b5F, nF, pF) are almost always used.<\/p>\n

Because it stores and releases energy cyclically, the capacitor opposes the passage of direct current but allows the transfer of signals that vary over time, such as alternating current signals. Capacitors can be polarized<\/strong> (meaning they have a mandatory mounting direction, such as electrolytic capacitors) or non-polarized (such as ceramic capacitors). The main data \u2014 capacitance and maximum voltage \u2014 are always indicated on the component body, either through colour coding or printed markings.<\/p>\n

In particular, electrolytic capacitors clearly indicate polarity: the positive terminal is generally the longer one, while the negative terminal is marked by a coloured stripe on the body of the component.<\/p>\n

Capacitor codes<\/h3>\n

Capacitors are also often marked with a code, generally consisting of three digits or three digits plus a letter. Of the three digits, the first two are significant figures, while the third is the multiplier. For example, a 100 nF capacitor is marked 104. The fourth character, if present, indicates the tolerance of the nominal value: M<\/strong> means \u00b120%<\/strong>, K<\/strong> means \u00b110%<\/strong>, and J<\/strong> means \u00b15%<\/strong>.<\/p>\n

\"\"<\/a><\/p>\n

Why are two capacitors often found together in the Pixie?<\/h3>\n

A natural question that arises when looking at the Pixie schematic is: why are there, in some parts of the circuit, two capacitors of different types placed next to each other? Two capacitors connected in parallel simply add their capacitances, but the reason here is different: no real component is completely pure<\/em>. Electrolytic capacitors are effective at minimizing voltage fluctuations (slow variations), but they are not suitable for reducing high-frequency noise; ceramic capacitors, on the other hand, are very effective at reducing high-frequency noise but not slow voltage variations. Although they appear to perform the same task, the two components therefore have complementary functions.<\/p>\n

The inductor<\/h2>\n

\"\"<\/p>\n

\"\"<\/p>\n

The inductor is a passive component that stores a small amount of energy in a magnetic field<\/strong>. It is made of coils of electrical wire, wound either in air or around ferromagnetic materials (for example ferrite, which increases its efficiency). Inductors are particularly important in radio circuits. Together with capacitors, they are in fact able to select or generate very specific frequencies: it is precisely by exploiting this property that we will build some of the fundamental circuits of the Pixie.<\/p>\n

Its main characteristic, inductance<\/strong>, is measured in Henries<\/strong> (H) \u2014 and here too, in practical applications, submultiples are almost always used, especially \u00b5H. Commercial inductors are available with standard values, but in amateur radio, especially in home-built projects, it is often necessary to wind them manually, calculating the required number of turns according to the desired value and the type of core used.<\/p>\n","protected":false},"excerpt":{"rendered":"

Before examining the Pixie schematic, it is necessary to be able to recognize, at a glance, the components we will find in the kit. Let us start with passive components: elements that do not amplify or generate energy, but store it, dissipate it, or control its flow. The resistor The resistor is a component that […]<\/p>\n","protected":false},"author":1,"featured_media":1148,"parent":1140,"menu_order":3,"comment_status":"closed","ping_status":"closed","template":"","meta":{"iawp_total_views":0,"footnotes":""},"class_list":["post-1147","page","type-page","status-publish","has-post-thumbnail","hentry"],"yoast_head":"\nPassive components - I8ZSE<\/title>\n<meta name=\"description\" content=\"Pixie Course: Let's get to know the passive components\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.i8zse.it\/en\/pixie\/passive-components\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Passive components - I8ZSE\" \/>\n<meta property=\"og:description\" content=\"Pixie Course: Let's get to know the passive components\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.i8zse.it\/en\/pixie\/passive-components\/\" \/>\n<meta property=\"og:site_name\" content=\"I8ZSE\" \/>\n<meta property=\"article:modified_time\" content=\"2026-07-31T15:03:13+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.i8zse.it\/en\/wp-content\/uploads\/2026\/07\/resistori-1.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"637\" \/>\n\t<meta property=\"og:image:height\" content=\"649\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"6 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.i8zse.it\\\/en\\\/pixie\\\/passive-components\\\/\",\"url\":\"https:\\\/\\\/www.i8zse.it\\\/en\\\/pixie\\\/passive-components\\\/\",\"name\":\"Passive components - 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