Saturday, September 7, 2019

Setting preferred units in Eagle CAD to metric or imperial

If you want to set Eagle CAD to display units in either metric or imperial, there is a simple command to do this.
SET Interface.PreferredUnit n
where n can be:
0 - the default value. Eagle decides if will display metric or imperial
1 - imperial
2 - metric

To change current units in Eagle CAD, simply paste the command in the command line, replace the n with your preferred value and press enter. To confirm that it worked, open the DRC window.

Changing from metric units to imperial in Eagle CAD
Imperial units in Eagle CAD DRC window

Changing from imperial units to metric in Eagle CAD
Metric units in Eagle CAD DRC window

Monday, August 19, 2019

How to build a zener and LED diode tester using a 555 timer DIY

If you have a bunch of salvaged Zener diodes you need a quick way to sort them. In this article I describe how to build a simple test equipment that can be used to measure the breakdown voltage of a Zener diode. It can also be used to test LEDs and their color, since sometime a color LED can look white when not lit. This Zener tester is powered from a 9V battery so it doesn't involve dangerous mains voltage and can measure diodes up to 90V with the help of a 555 timer boost converter. 

I also use it for checking for burned LEDs in a mains light bulb.

Zener and LED diode tester

Thursday, June 27, 2019

How water flows inside a washing machine

I had a broken Indesit WIE 107 washing machine and I was curious to know how water is distributed to 3 containers with only 2 solenoid valves and so I took it apart.

Washing machine water inlet distribution box teardown

Washing machine water inlet distribution box teardown
Top side (original)

Washing machine water inlet distribution box teardown
Top side (with markers)