Silicon Valley was Built on Tubes of Glass

Lee de Forest

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 already a controversial figure. He had founded a company in New York to develop his early vacuum tubes as detectors for radio, but he was not very good at business. Some of the officers of the company decided that progress was not being made fast enough and drained the company of assets while de Forest was away. This led to years of legal troubles and the arrest of many involved due to fraud and loss of investors’ money.

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California Looks to Compel IoT Security

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 is capable of connecting to the Internet, directly or indirectly, or to another connected device, to equip the device with reasonable security features appropriate to the nature of the device and the information it may collect, contain, or transmit, that protect it from unauthorized access, destruction, use, modification, or disclosure, and to design the device to indicate when it is collecting information and to obtain consumer consent before it collects or transmits information, as specified. The bill would also require a person who sells or offers to sell a connected device to provide a short, plainly written notice of the connected device’s information collection functions at the point of sale, as specified. The bill would require a manufacturer of a connected device to provide direct notification of security patches and updates to a consumer who purchases the device.

This is just a proposal and will change as it finds its way through committee. Currently there a really no methods of punishment outlined, but recent comments have suggested individual prosecutors may have latitude to interpret these cases as they see fit. Additionally it has been suggested that the devices in question would be required to notify in some way the user when information is being collected. No language exists yet to clarify or set forth rules on this matter.

The security community has been sounding the cry of lackluster (often lack of) security on this growing army of IoT hardware and we’ve all known one day the government would get involved. Often this type of action requires a major event where people were in some way harmed either physically or financially that would push this issue. Denial of service attacks have already occurred and hijacking of webcams and such are commonplace. Perhaps what we saw in September finally pushed this into the limelight.

Any reasonable person can see the necessity of some basic level of security such as eliminating default passwords and ensuring the security of the data. The question raised here is whether or not the government can get this right. Hackaday has previously argued that this is a much deeper problem than is being addressed in this bill.

The size of California’s economy (relative to both the nation and the world) and the high concentration of tech companies make it likely that standards imposed if this law passes will have a large effect on devices in all markets.

I Think I Failed. Yes, I Failed.

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 of long out of production parts to throw in there for audiophile cred, and I want some of that.

img_2857-2Lets use some cool retro transistors! I merrily go along for hours designing away. Carefully balancing the current of the long tailed pair input. Picking just the right collector power resistor and capacitor value to drive the transformer. Calculating the negative feedback circuit for proper low frequency cutoff and high frequency stability, and into the breadboard the parts go — jumper clips, meter probes, and test leads abound — a truly joyful event.

All of the voltages check out, frequency response is what you would expect, and a slight tweak to the feedback look brought everything right into happiness. Time to fire up the trusty old HP 334A Distortion Analyzer. Those old machines require you to calibrate the input circuit and the volt meter, tune a filter to the fundamental frequency you are applying to the device under test and step down to lower and lower orders of distortion levels until the meter happily sits somewhere in the middle of a range.

Most modern circuits in even cheap products just go right down to sub .1% total harmonic distortion levels without even a thought and I expected this to be much the same. The look of horror must have been pronounced on my face when the distortion level of my precious circuit was something more akin to a clock radio! A frantic search began. Was it a bad jumper, or a dirty lead in the breadboard, or an unseated component? Was my function generator in some state of disrepair? Is the Stephen King story Maximum Overdrive coming true and my bench is going to eat me alive? All distinct possibilities in this state of panic.

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How To Make Your Weller Wireless

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 we are ignoring the negative effects of switching DC current over AC current on mechanical contacts. After all we are “In the Trenches” wherever we might have need for such a device. Using a couple of gel cell 12 volt 7 amp hour batteries freshly removed from a UPS I strung them up, and there you have it, a totally battery operated  iron with performance equal to that of the one at my bench.

Connecting SMPS to the Weller Iron
Connecting Power to the Weller Iron

Right at 24 volts the iron Thermocycles at the same rate as it would be while using the bench top supply for it. Just sitting under no load it cycles about every ten seconds and there was no perceptible difference in heat capacity or performance. A fully charged pair of batteries will last all day. The on state current draw from a full charge (13.5 volts on each of the batteries) yielded about a 2 amp draw. As the voltage began to decrease the current off cycle would get shorter as one would expect, but no drop in heat transfer was noticed until the batteries were well depleted and that took most of a work day.

For this instance I used the hand piece from the venerable Weller WTCPT station. For ongoing use I would not recommend this due to the use of a mechanical contact within the unit and switching of DC can reduced the life of most mechanical switches. Currently I am awaiting the arrival of some cheap eBay Hakko handpieces; I am sure they are knockoffs, but fine to experiment with a simple PWM with a feedback loop controller as the basic Hakko design also utilizes a 24 volt source. An automatic shut off timer would also be handy to avoid premature battery abuse due to a forgetful operator.


Flying Close To The Flame: Designing Past Specified Limits

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.

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Artisanal Vacuum Tubes: Hackaday Shows You How

Homemade Vacuum Tube
Homemade Vacuum Tube

About a decade ago I started a strange little journey in my free time that cut a path across electronics manufacturing from over the last century. One morning I decided to find out how the little glowing glass bottles we sometimes call electron tubes worked. Not knowing any better I simply picked up an old copy of the Thomas Register. For those of you generally under 40 that was our version of Google, and resembled a set of 10 yellow pages.

I started calling companies listed under “Electron Tube Manufacturers” until I got a voice on the other end. Most of the numbers would ring to the familiar “this number is no longer in service” message, but in one lucky case I found I was talking to a Mrs. Roni Elsbury, nee Ulmer of M.U. Inc. Her company is one of the only remaining firms still engaged in the production of traditional style vacuum tubes in the U.S. Ever since then I have enjoyed occasional journeys down to her facility to assist her in maintenance of the equipment, work on tooling, and help to solve little engineering challenges that keep this very artisanal process alive. It did not take too many of these trips to realize that this could be distilled down to some very basic tools and processes that could be reproduced in your average garage and that positive, all be it rudimentary results could be had with information widely available on the Internet.

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