ESP now includes a blog – Anything new will be announced here.

ESP (The Audio Pages) now includes a blog.  Sorry, but there’s not much of interest here yet.  To see the real ESP site, just go to


I’ve been publishing electronics (primarily audio) information since 1999.

There is something new on the ESP site though.  Many people are experiencing ‘brown-outs’, where the mains voltage falls well below normal. This problem is worse now than it used to be, because most power companies are running their networks close to the limits, and they also use ‘renewable’ energy sources whose output can suddenly stop without warning.

If your refrigerator (for example) tries to run while the voltage is low, the motor may be unable to start.  This can lead to a burnt out motor in extreme circumstances, but Project 138 may well save the day.  Valve (tube) amplifiers are also vulnerable, and surprisingly, some transistor amps can get very upset too – especially if the mains voltage goes higher than normal.

I must warn anyone interested in building the circuit that it involves some serious mains wiring (in operation, the entire circuit is live), and should never be built by anyone not experienced or  qualified to work with mains power.

There’s another new project as well (well, it’s been on the site for about a month now).  Anyone wanting to build a portable powered PA system should look at Project 137.  It can also be used for powering Leslie (rotating) speakers commonly used with organs, or can be the basis of a pretty awesome party Hi-Fi system.  System power is 250W, and it’s not only very loud, but clean too!

Cheers,   Rod


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