Don't just use the tools — understand why
Every article is tied closely to one of the on-site tools, explaining the principles, trade-offs and pitfalls behind "press once, get a result." Hand-written, with original diagrams and quick-reference tables — by the time you're back at the tool, you'll know where every number comes from.
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From Truth Table to Boolean Expression: SOP, POS and Minimization
Every truth table maps to a Boolean expression two ways: sum-of-products built from the rows that output 1, or product-of-sums built from the rows that output 0. This explains minterms and maxterms, the canonical forms, and how to minimize what you get with a K-map.
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Karnaugh Map Tutorial: Simplify Boolean Logic by Hand (with Don’t-Cares)
A K-map turns Boolean simplification into a visual game: order the cells in Gray code, circle the biggest power-of-two groups of 1s, and read off the minimal sum-of-products. This walks through 2-, 3- and 4-variable maps, the grouping rules, and how don’t-care terms make the answer even smaller.
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Sign-Magnitude vs One's vs Two's Complement: How Computers Store Negative Numbers
Sign-magnitude and one's complement both waste a bit pattern on a second 'negative zero'; two's complement has exactly one zero and lets the same adder do subtraction. Here are the three encodings side by side, their ranges, and how to negate a number by hand.
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Binary, Hex & Decimal Conversion: How to Convert by Hand (and Read Signed Values)
Hex is just binary in groups of four bits — once you see that, hex↔binary needs no arithmetic at all. This guide covers the nibble table, decimal↔binary by repeated division and by place value, and why 0xFF is 255 unsigned but −1 as a signed byte.
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Op-Amp Pinout & Basics: LM358 / LM324 / LM741 and the Two Core Circuits
Pinouts for the three op-amps beginners meet first — LM358, LM324 and LM741 — with the LM324 power-pin trap (VCC on 4, GND on 11), the two gain formulas you actually need, and why a single-supply LM358 output cannot quite reach the rails.
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74HC Logic Gates: Pinout Cheat-Sheet and Truth Tables (00/02/04/08/32/86)
Six of the most-used 74HC gates on one page: NAND/NOR/NOT/AND/OR/XOR pinouts and truth tables — plus the gotcha that the 74HC02 NOR puts its output on pin 1 while every other quad gate puts an input there, and why you must never float a CMOS input.
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7805 / 7812 / LM317 Voltage Regulator Pinout & Wiring
The 78xx fixed regulators are IN-GND-OUT (tab = GND); the LM317 adjustable is ADJ-OUT-IN (tab = OUT) — swapping them is a classic mistake. The pinouts, the LM317 Vout = 1.25(1+R2/R1) formula, and the bypass caps.
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Transistor Pinout (E/B/C): How Not to Plug It in Backwards
Emitter, base, collector — which pin is which on a TO-92, and the gotcha that the 2N2222/2N3904 (E-B-C) and the BC547 (C-B-E) are mirror images. Plus how to confirm with a multimeter before you solder.
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74HC595 Shift Register: Pinout and How to Chain Them
A serial-in / parallel-out shift register that turns 3 microcontroller pins into 8 (or 16, 24…) outputs. The pinout, the role of DS / SHCP / STCP, and how to chain chips with Q7S → DS.
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NE555 Timer: Pinout, Specs and Typical Circuits
The NE555 pinout (GND/TRIG/OUT/RESET/CTRL/THRES/DISCH/VCC), key specs, and the astable f=1.44/((Ra+2Rb)C) and monostable t=1.1RC formulas — with typical values and a one-click calculator.
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How to Read Resistor Color Codes (4, 5 and 6 Band)
The full color-to-digit, multiplier, tolerance and temp-coefficient tables (IEC 60062), how to spot band 1, and the difference between 4-, 5- and 6-band resistors — with a one-click decoder to verify.
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LED Forward Voltage Chart by Color (Red to UV)
What forward voltage does a red, blue, white or UV LED drop? This chart lists typical Vf by color at 20 mA, explains why Vf drifts with current and temperature, and links straight to the resistor calculator.
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LED Current-Limiting Resistor: Theory and Sizing — A Complete Guide from Formula to Part Selection
An LED is a constant-voltage device — connect it straight to a supply and it burns out instantly. This article lays out the current-limiting resistor formula, the safety logic of rounding the E24 standard value "up", how to choose the power rating, plus the easy-to-trip-up details like multiple LEDs in series/parallel and USB voltage fluctuation.
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