Embedded Calculators & Part Finder
Size a value with 64 free calculators, then find the real component that fits — in stock, at the best price. For MCU, power, RF & firmware. No account.
★ Popular
💡LED Resistor
⚡Ohm's Law
🚌CAN Bit Timing
🔻Voltage Divider
🔠Glyph Mapper
📦Struct Padding
PWM / Timer
Frequency, period, duty cycle
UART Baud Rate
Error rate, PASS/FAIL check
ADC Resolution
LSB voltage, SNR, dynamic range
Watchdog Timer
STM32 IWDG & WWDG timeouts
I2C Timing
Bus timing & pull-up values
CAN Bus Bit Timing
STM32 bxCAN/FDCAN & MCP2515
SPI Timing
Bit period, frame, throughput
RS-485 Bus
Cable length, termination, bias
LIN Bus Timing
Bit, break, frame time
Modbus RTU Timing
Char & inter-frame gaps
Ring Buffer / DMA
Buffer sizing
Register Map → C
Bitfield struct & macros
CRC → C Code
Lookup table & function
Stepper Motor
Steps/rev, microstep, pulse rate
BLDC / PMSM Speed
Motor electrical freq, pole pairs
Rotary Encoder
Motor encoder counts/rev
Motor Torque ↔ Power
N·m, RPM, Watts, hp
MOSFET Power Loss
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LDO Dropout / Power
Heat dissipation & efficiency
I2S Audio Clock
BCLK, LRCLK, bit period
USB Data Lines
Bit time, 90Ω, termination
Ethernet Cable
Bit time, delay, 100m limit
Bit Field Visualizer
32-bit register breakdown
Q-Format Converter
Float ↔ fixed-point
Number Base Converter
Dec, Hex, Bin, Oct converter
IEEE 754 Visualizer
32-bit Float & 64-bit Double
Endian Swap
Big/Little/Mid-Endian byte swap
Struct Alignment
C struct padding & visualizer
Memory & Transmission
Bytes, baud rate & sample times
Glyph Mapper
7-Segment & Character LCD custom font generator
Crystal Load Cap
Oscillator load capacitor sizing
Ohm's Law
V, I, R, P — any 2 → all 4
Voltage Divider
Vout, loaded divider, Thevenin
LED Resistor
Series/parallel configs & E24
Resistor Code
Color bands & SMD decoder
Op-Amp Gain
Amp configurations & Schmitt
Instrumentation Amp
3-op-amp in-amp gain & Vout
Op-Amp Resistor
Inverting/Non-inv → R2,R3,R4
BJT Bias CE
Q-point & stability factor
NE555 Timer
Astable / monostable
Capacitor Charge
RC time constant, τ milestones
Buck / Boost
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AWG Wire Gauge
Wire gauge & voltage drop
Series / Parallel
R · C · L equivalent value
LM317 Regulator
Adjustable Vout & R2 solver
Current Divider
Branch currents in parallel R
LC Resonance
LCR resonant freq, Q-factor
RC Filter
Cutoff frequency, gain & phase
dB Converter
dB, dBm & mW bidirectional
CRC Calculator
CRC-8/16/32, 7 polynomials
Checksum / CRC
XOR, Sum8/16, LRC, CRC
PCB Trace Calc
IPC impedance & trace width
Active Filter
Sallen-Key 2nd-order LPF/HPF
RF Trans. Line
Microstrip impedance (IPC-2141)
VSWR / Return Loss
Γ, return & mismatch loss
RF Link Budget
FSPL, Rx power, margin
Wavelength / Antenna
λ, λ/2 dipole, λ/4 whip
Attenuator Pad
T / Pi resistor values (dB)
Coil Inductance
Air-core solenoid (Wheeler)
Battery Life
Estimated system run-time
Temperature
Units & RTD sensor temps
Wheatstone Bridge
Bridge Vout & balance
Junction Temp
Thermal Tj & max power
Resistive Attenuator (T / Pi Pad) Calculator
Compute resistor values for symmetric T and Pi attenuator pads at a given attenuation and impedance.
Input
ℹ Symmetric (matched) pad — same impedance Z₀ on input and output.
Results
T-Pad · R1 (series)—
T-Pad · R2 (shunt)—
Pi-Pad · R1 (shunt)—
Pi-Pad · R2 (series)—
💡 Usage & Formula
A resistive pad reduces signal level by a fixed amount while keeping the line matched to Z₀. Let K = 10^(dB/20).
- T-pad:
R1 = Z₀(K−1)/(K+1),R2 = Z₀·2K/(K²−1) - Pi-pad:
R1 = Z₀(K+1)/(K−1),R2 = Z₀(K²−1)/(2K)
Usage: Enter the attenuation and system impedance (50 Ω for most RF). Pick the T or Pi topology that gives the most buildable resistor values.
When you need it: Designing a matched resistive pad that drops signal level by a set number of dB while keeping the line at its characteristic impedance (usually 50 Ω).
Worked example: A 6 dB 50 Ω Pi pad uses a series R ≈ 37 Ω between two shunt Rs ≈ 150 Ω. The voltage ratio is 10^(dB/20), and the pad presents 50 Ω at both ports.
Tips & gotchas:
- Resistive pads are broadband and dead simple, but they dissipate the attenuated power as heat.
- T topology suits low attenuation; Pi is common at 50 Ω — both are matched two-ports.
- The input resistor sees the most power; rate it for the full input level at high drive.
- A pad also improves source/load match — a few dB of padding is a cheap VSWR fix.
📖 References:
Attenuator (Wikipedia)