Electronics 01
How to Choose a Pull-Up Resistor Value (With I2C Math)
Pull-up resistors have a minimum set by sink current and a maximum set by rise time and leakage. Worked I2C example at 400 kHz, plus MCU internal pull-ups.
Electronics
Electronics 02
MOSFET Gate Resistor Value: How to Choose It (With Math)
The gate loop is a series RLC circuit. Choose the gate resistor for damping 0.7 to 1, then check switching loss and pin current. Worked IRLZ44N example.
Electronics 03
How Does a Buck Converter Work? Worked 12 V to 3.3 V
How a buck converter works, from volt-second balance to Vout = D·Vin, with a worked 12 V to 3.3 V, 2 A design, computed waveforms and efficiency.
Electronics 04
How to Calculate Crystal Load Capacitors (With Stray C)
CL = C1·C2/(C1+C2) + Cstray, but which stray? Worked 18 pF example, the ppm error from getting it wrong, and the gain margin check most guides skip.
Electronics 05
Button Debounce Capacitor Value: How to Size the RC
Switches bounce for 1.6 ms on average and 6 ms or more at worst. How to size the debounce R and C from Schmitt thresholds, and why 10k with 100 nF is too short.
Electronics 06
555 Timer Frequency Formula: Where 1.44 Comes From
f = 1.44/((R1 + 2R2)C). Why 1.44 is 1/ln 2, why duty cycle can't drop below 50%, and why the diode fix misses 50% at 5 V. Worked 1 kHz example.