Author Archives: Charles Alexanian

Silicon Valley was Built on Tubes of Glass

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Bill Shockley brought the transistor to a pasture in Palo Alto, but he didn’t land there by chance. There was already a plot afoot which had nothing to do with silicon, and it had already been a happening place for some time by then.

Often overshadowed by Edison and Menlo Park or Western Electric and its Bell Labs, people forget that the practical beginning of modern radio and telecommunications began unsuspectingly in the Bay Area on the shoestring-budgeted work benches of Lee de Forest at Federal Telegraph.

As the first decade of the 20th century passed, Lee de Forest was …read more

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California Looks to Compel IoT Security

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There is a bill going through committee in the state of California which, if passed, would require a minium level of security for Internet of Things devices and then some. California SB 327 Information privacy: connected devices in its original form calls for connected device manufacturers to secure their devices, protect the information they collect or store, indicate when they are collecting it, get user approval before doing so, and be proactive in informing users of security updates:

require a manufacturer that sells or offers to sell a connected device, defined as any device, sensor, or other physical object that …read more

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I Think I Failed. Yes, I Failed.

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Down the rabbit hole you go.

In my particular case I am testing a new output matching transformer design for an audio preamplifier and using one of my go to driver circuit designs. Very stable, and very reliable. Wack it together and off you go to test and measurement land without a care in the world. This particular transformer is designed to be driven with a  class A amplifier operating at 48 volts in a pro audio setting where you turn the knobs with your pinky in the air sort of thing. Extra points if you can find some sort …read more

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How To Make Your Weller Wireless

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On occasion I have encountered portable soldering irons and my impressions of them have ranged from nearly usable to total rubbish. While using a popular butane powered model and pondering if it was really any better than a copper wire and a candle a thought occurred to me. A regular old Weller station runs on 24 volts AC and performs all of its temperature regulation in a magnetically activated thermostatic fashion and all of that goodness occurs within the hand piece itself. It stood to reason that it could perform just as well with a DC source.

In this instance …read more

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Flying Close To The Flame: Designing Past Specified Limits

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A very good question came up on The EEVBlog forum that I thought deserved an in depth answer. The poster asked why would amplifier companies in the heyday of tube technology operate tubes in mass produced circuits well in excess of their published manufacturers recommended limits. The simple answer is: because the could get away with it. So the real question worth exploring is how did they get away with operating outside of their own published limitations? Let’s jump in and take a look at the collection of reasons.

Materials-Based Tube Performance

First a brief discussion of what the limiting …read more

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