Passives (R, L, C)

Passives are the two- and three-terminal parts that resist, store, or divide — the ones you reach for in almost every circuit before any IC goes down. de:volt ships the Resistor, the Potentiometer, the Trimmer, the Capacitor (with Ceramic, Electrolytic, and Film body-style variants on the palette), and the Inductor. None of them have a datasheet to memorise; the behaviour is the value, and every value is editable in the Inspector.

Resistor

The plainest part in the catalog and the one you place most. A resistor sets a current for a given voltage (I = V / R) or drops a voltage for a given current. It is non-polar — pins a and b are interchangeable.

Pinout

Specs

The resistance param is the whole part — change it in the Inspector and the resistor becomes whatever you need. The tolerance param is the spread the Monte Carlo analysis draws from; at the 5% default a 220 Ω part can land anywhere from ~209 Ω to ~231 Ω across runs.

What you use it for

• Current limiting. A resistor in series with an LED caps the current the LED draws. For a red LED on a 5 V rail, a 330 Ω series resistor holds the current to roughly 10 mA: (5 V − 2 V_LED) / 330 Ω ≈ 9 mA. See /parts/leds for the per-colour forward voltages.
• Pull-up / pull-down. A resistor from a floating input to VCC or GND gives it a defined idle level so it isn’t left to pick up noise.
• Voltage division. Two resistors in series tap a fraction of the rail at their midpoint — the basis of every divider on this page.
• Biasing. Setting the quiescent operating point of a transistor or op-amp.

The four-resistor Resistor Array packs four isolated resistors that share one resistance value into a single SIP body — handy for ganged pull-ups on a bus. See /parts/passive-arrays-and-switches.

Potentiometer

A three-terminal variable divider: a resistive track of rTotal with a wiper that taps a point along it. Turning the shaft moves the wiper, so the wiper-to-end resistance varies continuously from 0 to rTotal.

Pinout

Specs

position is where the wiper sits, 0 at the CCW end and 1 at the CW end; 0.5 is mechanical centre. taper chooses how resistance tracks position: linear is proportional, log is the audio taper that matches how the ear perceives loudness.

Wiring it as a divider

Tie one end to VCC and the other to GND, and the wiper delivers a voltage that sweeps the full rail:

VCC ─── CW
         ├── (track) ── W ─── Vout (0 → VCC as you turn)
GND ─── CCW

With CW to VCC and CCW to GND, position = 0.5 puts the wiper at half-rail. Read the wiper on an analog input for a manual knob.

Trimmer

Mechanically the same divider as the potentiometer, but set once with a screwdriver and left alone — for calibration trims you don’t expect a user to touch. There is no taper param; trimmers are linear.

Pinout

Specs

Wire it exactly like a potentiometer — ends to your reference voltages, wiper to the node you’re trimming. The lower p_max reflects the smaller body of a real trimmer.

Capacitor

A capacitor stores charge on two plates; its voltage can’t change instantly, so it smooths, couples, and times. The generic Capacitor part carries a style param that selects the body — and the palette also offers three pre-styled variants so you can grab the right one directly.

Pinout

Specs

The style param doesn’t change the math the engine solves — it sets the part’s identity, polarity behaviour, and the tolerance band Monte Carlo draws from. Pick the variant that matches how you’d actually buy the part:

Ceramic (cap-ceramic)

Default 100 nF, non-polarised — either terminal can sit at the higher voltage. The workhorse decoupling cap. Place one within two breadboard columns of each IC’s VCC/GND pins so it can supply the fast current spikes the chip demands before the rail sags. Tolerance ~±10% for common X7R dielectrics.

Electrolytic (cap-electrolytic)

Default 100 µF, POLARISED — pin a is the positive (+) terminal and pin b is the negative (−). On a real part the negative leg is marked with a stripe; wiring it backwards breaks down the electrolyte and destroys the part. Use it for bulk rail filtering and for timing where you want a large value in a small footprint. Tolerance is loose (~−20%), so treat the value as a floor.

Film (cap-film)

Default 1 µF, non-polarised. Tight tolerance and stable, so reach for it in audio coupling, snubbers across switching contacts, and precision timing where a ceramic’s drift would matter.

Inductor

The dual of the capacitor: it stores energy in a magnetic field and its current can’t change instantly, so it resists changes in current. Non-polar, pins a and b.

Pinout

Specs

Inductors show up in RF filtering, in switching converters (where they shuttle energy between the input and output each cycle), and in tuned LC circuits paired with a capacitor. The inductance param is editable in the Inspector. Because an inductor fights sudden current changes, switching off the current through one produces a voltage spike — the reason inductive loads like relays and motors need a freewheeling diode across them (see /parts/diodes).

Placement

All of these are through-hole and breadboard-friendly. Straddle the centre gap or sit them in a single rail group as the circuit needs; the three-terminal pot and trimmer want their three pins on separate tie-points. See /user/breadboard-mode for how rows and rails connect.