Sunday, June 9, 2019

Crystal Capacitor Calculator

I needed a simple crystal capacitor calculator, the formula used is: C = 2*Cload – 2*Cstray (taken from

Just fill in C_load (from crystal datasheet) and C_stray (depends on PCB layout), then, press the calculate button.

CL:  (from crystal datasheet)

CS:  (from PCB layout)

C:  (this is the capacitor to be connected to the crystal)

Optional: Make sure that CL and CL_Actual is not too far from each other.
Actual C_load if using the calculated value [CL = (C1 * C2) / (C1 + C2) + Cstray]

Wednesday, April 10, 2019

Simple Open-Collector Comparator with Pull-up Resistor Hysteresis Level (Inverting Schmitt Trigger) Calculator

Most of the calculators on the internet are designed for push-pull output comparator, while they are handy, I do find myself wanting to use an open-collector or open-drain comparator instead.

As described by the title, this is a simple javascript-based calculator to calculate VH and VL.
No styling applied, so, it will look a bit ugly. 😆

There is no input-sanitation, so, make sure to only put plain numbers.
Let me know if you spot any careless mistake in the maths. 😁