February 2

Psychic Gaussian Transmodulator

From the travel journal of Alexander van Helsing:

“A few weeks ago, I received a curious letter from Bishop Waffelaert.  With the enthusiastic support of King Leopold II, the church of Sint-Petrus-en-Pauluskerk (Saint Peter and Paul) was to be built on the ashes of the previous church, destroyed so long ago.  Construction in Ostend has been underway for several months at this point, and the Bishop was present to oversee all spiritual matters there.  There have been increasing problems, however, since the clearing of the site; men attacked, supplies destroyed, and beasts running mad. Continue reading

October 22

Kyocera Car Charger hack

Cell phone car chargers are plentiful, inexpensive, and rarely compatible with a new phone.  An upcoming car trip created a need for a small variable supply I could use for the duration.  These factors, and a mention of hacking phone chargers on one of the sites I regularly read inspired me to crack open an old charger.

Initial Device

To the right is a Kyocera charger, split open.  There were no screws holding it together; a series of plastic posts kept the two halves together.  Careful application of a flat-bladed screwdriver pops it apart.  Inside was a delightfully accessible circuit board – the components were all labeled and through-hole, and the IC was unobscured. Continue reading

October 20

Voltage triggered switch

Minimum Voltage Indicator

This is a simple analog circuit that can be used to indicate if a minimum voltage is present at Vcc.  Minimum voltage is primarily determined by the zener voltage Dz.

Overview of how it works:

When Vcc < the zener breakdown voltage of Dz, the voltage drop across R1 and R2 are close to zero.  This means the voltage at base of the PNP transistor Q1,B is ~Vcc.  When VEB < VEB,on, the transistor does not conduct.  Therefore, current through R3 = 0, and the voltage drop across R3, defined as EN, is 0V.

Once Vcc > VZ, current starts to flow through R1.  Once there is sufficient current through R1 such that VR1 > VEB,on, Q1 begins to conduct.  This causes a voltage drop across R3, and EN to measure a >0 voltage (up to Vcc – VCE,sat).  R2 is in place to limit the current from the base of the transistor (as part of Q1’s conducted current will flow through the base from the emitter). The sensitivity of this circuit to the specific turn-on point and the Vcc/EN curve are strongly dependent on the values of R1 and R3, and somewhat dependent on the current knee of the zener diode.

Further notes and comments:

This circuit as presented optimizes cost and provide a high signal when Vcc is above the minimum.  Variations on this circuit include

  • a low signal at EN when Vcc is above minimum, using an NPN and flipping the circuit’s topology
  • Using a P-channel MOSFET for Q1 would eliminate the need for R2

As a note, a single LM431 (available from many manufacturers) can also perform a function similar to the “low EN” variation of this circuit with only a pair of external setpoint resistors and a pull-up resistor.  Which approach you choose depends on your application and need; the above could be advantageous for reason of cost, polarity (high EN when over Vcc,min using LM431 requires an inverting component), or voltage range (Maximum operating voltage of a LM431 is 37 volts, discrete bipolar transistors can operate in the hundreds of volts).

August 13

Youth Happens

I learned something new today: a new way to be annoyed and offended!

An older coworker came to me and asked for a “p-clip”.  When I asked him what a p-clip was, he replied “Never mind, you are too young to know what that is.” and walked off. I found myself angry, and highly offended. Benadryl and allergies are making me more cranky than usual, but the reaction was stronger than I anticipated.

P-clip, p-clamp, cable clip
P-clip, p-clamp, cable clip

On reflection (after a few seething minutes), my reaction makes some sense: I was accused of being unhelpful due to the ignorance of inexperience with a single specific term plucked from a dozen different possible disciplines, each of which have thousands of general and specific terms that can vary by age, experience, and even macro- and micro-geographically, then was dismissed in a manner to say that I was not worth the time to educate.  I did take some satisfaction from finding out that the older coworker next asked the Greybeard (probably twice my age, all years in multiple fields), and the Greybeard did not know what the older coworker was talking about either.

As a side note, I was able to find out what the older coworker was asking after in the time it took to fire off a single search engine query – had he felt that he did not want to or could describe to me what he needed, a wait of almost fifteen seconds could have brought me up to speed.  This is perhaps one of the great generational misunderstandings: that the Millennials and later generations have grown in and with the tools to quickly reference, absorb, and integrate data points.  Debate will continue on how this will help and/or hinder the underlying social and intellectual fabric of the future, but the ability to reference a single new and possibly strange term are undeniable.

I did address my concerns to the coworker – he felt they did not want to “waste my time” explaining it to me, and was surprised and concerned that he had caused offense.  I think when he made the comment he thought he was being funny.

Did I over-react? I dunno.
But I did learn something today.

April 20

The Morality of Spare Change

The other day a man approached me in the parking lot as I was leaving the grocery store. He asked if I had a spare dollar for an emergency – he needed gas to get someplace.  I told him that I had no cash, as I did not carry any normally, apologized, and wished him well.

The brief conversation on the way home with my companion on this touched on addressing this sort of situation.  My companion was surprised that I even acknowledged the person.

I maintain that you cannot simply ignore a person.  To ignore them is to deny them the most basic human dignity: acknowledging someone costs you nothing more than a few moments of time, and to deny someone even the small concession of recognizing them as a human addressing another is cruel.

Yes, this will put you into the situation where you must address what the person is wanting.  It may be spare change.  It may be truly an emergency of the sort that the most basic level of humanity demands we render aid (such as dire and/or life-threatening circumstances), and indeed to form the habit of ignoring the pleas for help around us makes us ignore immediate demands of action, and denies us an awareness of our surroundings and the situation of the people in it.

Even if it is spare change or similar aid, you must look at the person who is asking for a quarter, or a dollar, or whatever you can spare, and  answer them.  This is a service to you as much as them – your answer forces you to assess yourself.  Can you spare money?  Will you?  Why, or why not?  Will you lie to this person?  Why or why not?  Do they make you uncomfortable with their request?  Why or why not?

Our lives are made up of moments that are revealing.  Choose to use them, to learn about yourself.  Reflect, find answers, and change slowly if you do not like what you find.

Attention must be paid.  To others, and to yourself.

January 16

Technology is insanity

“Insanity is doing the same thing over and over again but expecting different results.”*

Technology is complicated.  The devices we interact with each day are simplified interfaces concealing layers of devices creating systems of subsystems linking other subsystems with interlocking peripherals and a sprinkling of manufacturing variances and use-based fatigue.

And that is just the toilet.  Your cell phone is far worse.

Yet, every time you sit down to do a little paperwork in the one-man no-pants cube, you expect when you sign off, stand up and press that little lever, your contribution is processed.  On the whole, that turns out to be true.  Unless you filed a particularly large document, or the latest auto-potty forgets to flush this time.

We used to hold all of our technology to that standard: do something, get a result; repeat same thing, get same result.

Then came computers.
Then cell phones.
Then smartphones, a wondrous merging of the two.

Computers repeatedly reinforced the idea that you could repeat the same actions and get different results.  Not all the time, but occasionally doing something or even nothing would result in a change in state of your machine.  This being due to the layers of abstractions and interfaces that make this astoundingly complicated tool relatively easy to use.  Same thing, different results.

Seems a bit insane.

Cell phones introduced us further to this.  If you stand in one spot, unmoving, you could have a strong signal, a weak signal, or no signal, and this will change as you stand, motionless, changing no parameters.  Dropping calls, making but not receiving calls, delay times in minutes to days of texts, notifications not coming through – all variable events that seem to be entirely disconnected from any action you take**.

The insanity marches forward.

Smartphones are the pinnacle of this disconnect: they communicate constantly with cell towers and all the peripherals in their system, getting notifications, sending and receiving data, and generally doing lots of stuff even when you aren’t touching them.  You may be aware of this or not, but the seemingly arbitrary changes in behavior of your device are multiplied here.  You can do the same thing with your smartphone and get different results.

Insanity.  And you are not surprised when this occurs, either.

You are now expecting insanity.

This is why people get so very angry and frustrated at technology.  They don’t seem to have any control over making it work or not.  If you run a test where you give someone a task and arbitrarily punish them whether or not they do it correctly, they become frustrated, angry, defiant, and sullen.  Further, since it is arbitrary, it looks like an inability to use technology (a black mark in social standing).

So why does the world seem insane, populated by cranky and randomly angry people?  Hmmmm…


* Attribution varies, from Rita Mae Brown in her book Sudden Death to Benjamin Franklin to Albert Einstein.  Precise attribution is irrelevant in this case.

** There are rational, explainable reasons why these events occur – the fluctuation of the reported signal strength, for example, is dependent on your position, but also, the EM field around you, between you and the tower, objects between and behind you and the tower, tower load, and more.  This does not change the experience.

January 15

Tech – Fulmen Hominem

From the laboratory notes of Abraham van Helsing

Generation of high differential tension and effect on tissue (living and dead)

Who is not familiar with the galvanic reaction?  While Galvani made many fine contributions to science, history will best remember him for his demonstration of the invigoration and  reanimation of a severed frog’s leg by means of electrical application.  This most fascinating application, taken to an extreme by the hubris of doctor Victor Frankenstein, suggests a use for this phenomenon somewhere between a twitching severed limb and a monstrous creature last spotted above the Arctic circle.

I have had the occasion and privilege of speaking at length with a brilliant Austrian, Nikola Tesla, at the Exposition Universelle in Paris.  The brunt of our conversation fixed primarily on Herr Tesla’s furtherance in generating large differential potentials from meaner levels.  His demonstrations of lightning summoned and tamed by his hand were like watching a Zeus of old.  While his displays harmed him not, he noted that without his preparations, the wrath of the tamed bolts would be terrible to behold.

On the train back from the Exposition, my mind had occasion to wander from Herr Tesla’s display to Volta’s demonstration of Galvani’s work.  While the apparatus Tesla employs for his work was great in power, so too was it in bulk.  If, perhaps, less power were employed, the size may be reduced to something a man may easily carry?  For  any tissue, whether it belong to those living or once living, will jump and tense to the influence of a bolt of electricity.  Among the creatures I have read of or even had the occasion to face, all shared the commonality of flesh.  To this end, their bodies betraying their will by the introduction of a high potential, I bend my next focus.

The resultant device created quite satisfying displays, and its damped bite was enough to deny me the use of my hand for a notable duration.  I must note that the full effect must be terrible indeed to be effective against the things outside man’s usual sphere: to this caution must be taken not to introduce the effects of this on a man, as the result will be most severe.  The device proved, the next challenge comes in reducing the size of coils and galvanic pile to something that can be carried – currently the excitation device occupies much of a laboratory table.”


As part of a costume for the character of Abraham van Helsing (less the bold scholar of medicine in Bram Stoker’s Dracula, more the swashbuckling character in a recent movie), I created several props of varying degrees of function.  One of them is this baton capped with man’s lightning.  For this, I gutted an inexpensive stun gun, and formed the rod around the secondary, high-step transformer.  The priming circuitry, responsible for stepping 9V up to a few hundred, was housed in an arm guard that was frankly ugly.

The central ball was one of the output electrodes, and the guard ring around it the second half.  When it was energized, arcs would strike at random around the ring.  The energized section was isolated from the control by an acrylic rod (illuminated with an LED for effect)

Notable problems I had with this device:

  • Variable display: the arcing display would not be consistent, varying with environmental conditions and ring oxides, from violet tracers (like a plasma ball) to full arcs, to no arcs.
  • Insulator breakdown: I do not know if the potential reached the neighborhood of the advertized 100kV, but the insulation between the outer bronze conductors and the hidden wire to the secondary transformer developed a flaw.  It began arcing across the base.  Once the initial strikes burned through the insulation, I could not create a good replacement.  I tried stripping the area and filling it with hot glue, resin epoxy, clay, even silly putty (which burns interestingly, by the way).

It was a learning experience, and one I think I will revisit at some point to finalize.  I have some corona dope, so I am hopeful.

January 12

Toy LED Lantern

The culprit, functional now
The subject of this discussion

Lights are an impulse buy I constantly struggle against. Soooo many lovely varied options.  My young son gives me new excuses to give in to that impulse.  On the Fourth of July, I was shopping at Michael’s when I found an LED lantern in the discount bin.  It seemed sturdy enough, with good fittings and a solid-feeling switch.  So I gave in to the impulse. After all, my son will be out after dark tonight, right?  He will need the lantern.

I loaded it up with 4xAA (NiMH, but the lower voltage shouldn’t cause any performance issues) and we took it to the evening fireworks show.  The lamp was bright through the evening, and my son turned it on and off at his whim. On the way back from fireworks, however, the new little plastic lantern started flickering.  I cracked it open, expecting a loose wire, or cold solder joint – both common problems in cheap consumer goods, especially with ROHS directives and lead-free solder.  The litany of problems went far deeper than that. The three white LEDs were wired in parallel, a fair design choice.  It could have used one fewer batteries at that point, but we will let that pass.  They were current-limited by a 22Ω, 1/8W, 5% resistor, which I noticed was hot to the touch.  Very hot.

Running the calculations*, each branch of the LEDs were running at ~37mA, which is 120% of their MAXIMUM rating.  Further, the resistor was dissipating ~260mW, about 200% of its maximum rating.  As a side note, the resistor had externally visible voids and a poor paint job, indicating possibly a rejected part (aka cheaper); it did measure within tolerance, though. As it turns out, one of the LEDs was partially burned out – occasionally working, occasionally shorting, causing the whole unit to flicker.  This particular LED configuration is not fault-friendly – if one shorts, the entire set goes out; if one opens, the other two LEDs each experience half of the burned-out LED’s current in addition to their own.

Oh, also the wiring was flimsy with cold soldering and no strain relief and part of the diffuser latch was cracked.

Many parts of this product were shodding (opposite of shining) examples of the shoddy engineering and poor foresight that plagues many consumer goods, many of which could be rectified inexpensively and easily.   Using a 33Ω instead of a 22Ω resistor (1/4W) would dramatically decrease the failure rate of these products, cutting down on returned product.  The human eye is not very sensitive to differences in high light levels, and LED life sharply decreases with higher currents / overcurrent.  I would venture that the consumer of a toy lantern is not looking for a room-lighting device so much as a rugged, long-lasting device.

This has turned into something of a rant.  In the end, I repaired the lantern with some white LEDs I had on-hand and a correct 33ohm resistor. Take-away lessons:

  1. A 1/4 cent oversight/savings can be rectified with $1.51 in parts and $100 in equipment – on a $5 plastic lantern
  2. Don’t be afraid to open up a product, and do question everything. Just because it is on the market does not mean that it is correct, and price tag does not dictate quality. There are some quite elegant solutions found in cheap toys, as well as appalling oversights.
  3. When buying cheap toys, don’t loose your receipt. You can’t take it back, and then you have to fix it.  :)

* Simple LED current-voltage calculations for single and paralleled configurations, derived from Ohm’s Law and Kirchhoff Current Laws A single LED driven by a voltage source and with a current limiting resistor is defined by the following equations:

I=\frac{V_{s}-V_{f}}{R}       OR       R=\frac{V_{s}-V_{f}}{I}

  • Vf is the forward voltage drop of the LED (a characteristic of the LED based on its color) [volts]
  • Vs is the voltage source [volts]
  • R is the value with a current limiting resistor [ohms]
  • I is the current through the branch (from the voltage source, through the resistor and the LED) [amps]

Given the forward voltage (available on the datasheet or package for the LED, or here) and the maximum continuous current (again, datasheet or package), you can determine the resistor needed, rounded to the next largest standard resistor value. With this information, LEDs wired in parallel (all anodes tied together and all cathodes tied together) being limited by a single resistor would be described by:

I_{LED}=\frac{V_{s}-V_{f}}{R \cdot N}       OR       R=\frac{V_{s}-V_{f}}{I_{LED}\cdot N}

with N being the number of (identical) LEDs wired in parallel.  ILED now only describes the current through a single LED. The calculations above were used with the assumptions of Vf=3.6V, ILED=Imax=30mA for LED characteristics, which are typical for a white “superbright” type LED.

January 12

IRL

You might believe there is a certain irony in writing this here in this medium.  However, on reflection, I think you will find that it is not the message, and this is the most effective way to address this issue.  I mean, who reads street fliers?  You may have to look up from your entertainment.

Look, a segue.

I propose a bit of a challenge.  Unplug, and engage.  I highly recommend it, and when the introvert engineer is recommending you look around, perhaps attention should be paid.  Put down your devices, your media and infotainment, from any sort of escapism or entertainment or media stimulation.  I don’t propose anything crazy, like a week or even a day.  An hour is a good number to regularly do – think of it as exercise for your senses.  Choose an hour a day you normally would be able to entertain yourself (it is useless to say, for instance, an hour at work where you wouldn’t be allowed access anyway counts).  Better, choose something that you would normally seek entertainment for.  If you listen to music between classes, or check your favorite web updates on a commute (NOT while operating the vehicle, I hope), or would dive back into a book/ebook in the ten minutes before an appointment, refrain.  Don’t seek the distraction – instead look around and observe other people, your surroundings, the environment.

Whyever should you do such a mad silly thing, though?  Its a valid question.  I did and still often do fill gaps between events, and idle minutes stretching to hours on such entertainments.  One such entertainment is streaming comedy – continuous hours of a variety of such folk.  I find I don’t laugh much (apparently the live experience helps; or is it the live alcohol?); even so, all but the worst genitalia-airlines-and-racial-joke comedians have some grain of insight into human behavior and condition.  More, less, insightful, or useful depends on the recipient.  One such comedian (who I do not remember the name of) was remarking on the “dumbing” of modern Americans.  Among his other forgettable anecdotes, he noted that people of the last century had more down time on their brains – they did not have access to any sort of constant media.  He postulated that they thought more as a result.

I find his conclusion incomplete, but the line of reasoning was heading in the right direction.  Our brains need idle time.  Mulling time.  Random thought time.  We are social creatures.  Even me, an introvert engineer who frequently refers to the people around me by species.  We do need time in nature, even just seeing trees or grass.

Electronic, painted, printed, or even imagined substitutes are not equivalent.

My point?  Spend a little time each day being bored, being observant.  Allowing your brain to rest is healthy.  Observing your surroundings, the behaviors of people around you, feeds your mind like a book (albeit a rather obscured plot).