Reading Components
Decode resistor color bands, 3-digit ceramic-cap codes, and electrolytic markings — the cheat sheet every guitar-pedal builder needs at the bench.
Why you need to read this in the first place
You ordered 50 resistors from Tayda. They show up in a little ziplock, all the same beige cylinder, with no markings except some colored stripes. Welcome to one of the small but real pains of pedal building. The good news is that the color code is genuinely simple and you'll have it memorized after maybe ten builds — much faster than you'd think.
Resistor color bands
A standard 4-band resistor reads like this: the first two bands are digits, the third is a multiplier (×10ⁿ), and the fourth is a tolerance.
The digits, in order from 0 to 9, are: Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White. The classic mnemonic is unprintable; pick your own.
So Brown-Black-Orange-Gold = 1, 0, ×1,000, ±5% = 10 kΩ. Yellow-Violet-Red-Gold = 4, 7, ×100 = 4.7 kΩ. Precision 5-band resistors add a third digit before the multiplier — same idea, one more band.
Ceramic caps (the little disc and box ones)
Ceramic caps print a 3-digit number on the body. The first two digits are the value, the third is a multiplier — and the units are picofarads (pF). So 104 = 10 × 10⁴ pF = 100,000 pF = 100 nF = 0.1 µF. 223 = 22 × 10³ pF = 22 nF.
You'll see a lot of 103 (10 nF) and 104 (100 nF) in pedals — they're the most common coupling and bypass values. When in doubt, hit the Cap Code calculator under Tools.
Electrolytics (the cans with a stripe)
Aluminum electrolytic caps are easy: the value is printed plainly on the side, e.g. '47 µF 25V.' But they're polarized — they only work one way. The longer leg is the positive lead, and there's a white stripe down the side marking the negative leg.
Get the polarity wrong and the cap will work just fine for a few seconds, then make a tiny popping sound and stop being a capacitor (sometimes with a puff of magic smoke). Always double-check the orientation against the silkscreen before powering up — and use a voltage rating at least 50% above your supply (so 16 V or higher for a 9 V pedal, even if a 10 V cap would technically fit).
Film caps and the rest
Polyester/film caps (the box-shaped ones, often green or brown) print their value the same way as ceramics, but you'll sometimes see formats like '2A104J' — the '2A' is voltage code (100 V), '104' is the value (100 nF), 'J' is tolerance (±5%). They're non-polarized, so orientation doesn't matter.
For everything else weird, Pedal Bench's Tools tab has a calculator that takes the printed code and tells you the value, voltage, and tolerance. Bookmark it.