Archive for July 2009

Floating measurements

A floating measurement reads the voltage between two points, neither of which is at ground potential. A most typical floating measurement done quite often is when doing voltage measurements with a battery powered multimeter. The floating insulated multimeter allows doing floating measurements of slowly changing signals easily. The advent of switching power supplies and motor

Syncing Music and Fireworks

Design News has published an interesitng on-line article Gadget Freak Case #128: Syncing Music and Fireworks on how Deane Williams fixed up his PC to synchronize fireworks with music. He used his PC’s parallel printer port to connect the circuit controlling the fireworks. The software was written in Agilent VEE 8.0 but Williams says it

Ethernet history

In 1973, Bob Metcalfe sent an internal memo to his colleagues at Xerox proposing a local system of interacting workstations, files, and printers. The devices would all be linked by one coaxial cable, he said, and would run within a local area network. He called the system an Ether Network, or Ethernet. And 36 years

MOSFET testing

Multimeters are very good tools to find out problems in electronics circuits and testing electronics components. Resistor measurement is found in practically all multimeters, capacitance measurement range is becoming more and more common and some high-end models can also measure inductance. Many multimeters have also possiblity to test bipolar transistors (Hfe measurement range), but I

Controlling dangerous things safely

Fire When Ready – A Pyro-Electric Safety Primer is a great document on issues around controlling dangerous things electrically. The document tells the techniques used on pyro/fireworks electrical control. Quite similar practices are used in other control applications where potentially dangerous things are controlled using electrical circuits or electronics.

Grounding outside

Inside building there are situations where you can see 60-115 V AC between different equipment grounding points. When going outside the building the voltage differences can between different grounding points can become larger. In electrical engineering, Earth Potential Rise (EPR) also called Ground Potential Rise (GPR) occurs when a large current flows to earth through

Parallel port still popular

The traditional PC parallel port is getting more and more rare on new PCs. It could be said that the parallel port is practically dissappearing from the PC technology. For example my new PC I use (bought more than year ago) did not have parallel port in it. Started documenting parallel port controlling document Parallel