EEVblog uCurrent - Precision nA Current Measurement Assistant

Here is another useful circuit from EEVblog, that can be used to measure from pico amps to amps current.

Clearance Holes for Metric Fasteners

When designing a PCB board, it is important to determine the necessary clearance for screw holes. The table below shows the general screw sizes and the corresponding hole clearances.

PCB Design : Via Current Carrying Capacity

Maximum via current carrying capacity can be calculated using Saturn PCB Design Toolkit

Commonly used via size and current carrying capacity are as below.

Altium Designer : Layer Stacks for 2 and 4 Layers PCBs

Design > Layer Stack Manager

Absolutely free and easy to use Software Tool for Engineers

1) gerbv - A Free/Open Source Gerber Viewer

You can download the source code from this page.

2) View 3D objects with STP viewer

Direct download link is here.

3) FreeCAD

Download Link is here.