Tools

Each calculator shows the formula, the parameters it uses, a worked example, and the checks it applies.

• Resistor Color Code Decoder

  Decode 4-, 5- and 6-band through-hole resistor colour codes to resistance, tolerance and optional TCR.

• AMS1117-ADJ Calculator – Resistors, Dropout & Heat Check

  Pick AMS1117-ADJ resistors with standard values, then check dropout, the 10 mA minimum load and junction temperature before you build.

• Battery Life Calculator

  Estimate run-time from battery capacity in mAh, average load current and an optional derating factor.

• CH340 Selector – CH340G vs C vs E vs B, Pinout & 3.3 V Use

  Pick the right CH340 variant by crystal, package, modem lines, temperature and 3.3 V supply, with the WCH pin differences and baud-error figures for each.

• Capacitor Calculator

  Capacitive reactance Xc at a frequency and RC time constant τ from resistance and capacitance.

• LED Series Resistor Calculator

  Size the series resistor for one LED string from supply voltage, forward voltage and current, then pick a nearby E-series value and check resistor power.

• Ohm's Law Calculator

  Solve V = I × R for voltage, current or resistance when you know the other two.

• MP1584 Calculator (NRFND) – Resistors, RFREQ, Inductor + MP2338 Notes

  Set MP1584 output and frequency resistors, size the inductor and check the 100 ns minimum on-time. MPS lists MP1584 as not recommended for new designs; see what changes with MP2338.

• Parallel Resistor Calculator

  Combine resistors in parallel or series. See the equivalent resistance and the conductance of the network.

• LM2596-ADJ Calculator – Feedback Resistors, Inductor E·T, Min VIN

  Set LM2596-ADJ output with standard resistors, get the inductor E·T value TI uses, and check minimum input voltage for TI, onsemi or XL2596 parts.

• Electrical Power Calculator

  Compute DC power and the third quantity from any two of voltage, current and resistance using P = VI, I²R and V²/R.

• TL431 Calculator – Output Voltage & Cathode Resistor Window

  Calculate TL431 divider resistors with Iref error, the valid cathode-resistor range for your input and load, and SOT-23 power and temperature rise.

• TP4056 Charge Current Calculator – RPROG, Heat & Cutoff

  Set TP4056 charge current from RPROG, check chip temperature at your battery voltage, and see why "1.2k = 1A" tables disagree with the datasheet.

• Voltage Divider Calculator

  Find the tap voltage of a two-resistor divider, see how a load pulls that tap down, and check the current and power in each resistor.

• Electronics Unit Converter

  Convert resistance, voltage, current, capacitance, inductance, frequency, time, power and energy with SI prefixes.

• Reactance Calculator

  Capacitive Xc and inductive Xl from frequency and capacitance or inductance.