High current Molexia, or “why’s the dryer acting stupid?”

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This is what you get when Molexia strikes at about 20 amps of load. It doesn’t smell great.

On a side note, I now understand why some dryers have a broken belt interlock switch that the belt tensioner lands on if it goes slack. On this Frigidaire stack unit, a broken belt lets the tensioner arm land on the motor shaft, causing them to loudly wear a divot in each other and rain metal fillings down into the chassis below.

There was also a completely disintegrated foam gasket that interfaces the lint filter/exhaust duct to the blower inlet.. I never took a picture of it, but my solution was to angrily glob half a tube of rtv silicone there to stick the two back together.

Good Enough For Museum Work.

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Pooped Pop Video Player!

Updated: Do not, for the love of cheeeeze, bump this thing while it’s running or it will throw a big scary blue screen NMI / parity check error and scare you to the very core of your being

wpid-wp-1435769410872.jpg Well well well, would you look what tripped and fell on its face today? This is an old Visual Circuits POPVideo Player, from the late 1990s. Amazingly, the only problem here was a bad power supply.

But let’s look inside, because, oh man, this thing should be a computing history museum piece.

 

The year was 1990-something. People were still dancing the Macarena everywhere. Grunge rock was still going strong, accompanied by some pretty nice sort of folk music, a lot having female vocalists and very little Studio Magic. Digital signage was just starting to really catch on and replace static signage in advertising and the like, using CRT televisions or video projectors… and the Pop Video Player was ready and willing to drive this.

The features: Hard disk video storage of MPEG-2 content… updatable via changing the removable hard drive out, or over IP via modem (!!!) or Ethernet interface. Windows NT 3.51 or 4.00 (hurrrrk!) based machine on an AMD K6-2 at 200 mhz…

Needless to say, a PC of this thing’s stature would have trouble playing any sort of video, so it’s got some custom hardware. Special cards with four MPEG-2 decoder ASICs, audio codecs, and framebuffers with S-Video and composite outputs were used. The software then only has to fill the buffers on each of the MPEG-2 decoders and respond to control commands which could be sent in by serial port (possibly over IP?).

And here we go on the magical history tour.

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Brand Name Necrophilia

There’s a really weird situation with brand names, especially in consumer electronics, that really kinda drives me nuts.

So we had a lot of big companies in the electronics industry… to name a few, Curtis-Mathes, Westinghouse, Memorex, Magnavox, and even Commodore, which ceased to be over the years. Yet, you can buy products that are supposedly made by them today. Said products are complete and unfettered Chinese lowest bidder garbage. I call the situation “brand name necrophilia”.

What happened?

Crappy Funai VCR guts
Crappy Funai VCR guts

The problem is, their brand names were taken as more valuable than the companies. When those companies went bankrupt, or otherwise ceased operation, their brand names were sold to a licensing company that specializes in renting them out to an importer or retailer to have them stamped on whatever junk they’re bringing in, in hopes that the brand name recognition will fool consumers into thinking the product is actually designed, manufactured, and supported by a well established company.

You couldn’t be more wrong, sorry! That Westinghouse TV is nothing like the set you bought from them in the 70s. Enjoy the fact that it will take 3 seconds to respond to the push of ANY button on the remote and will fracture the screen if you as much as breathe on the bezel.

Good examples of this happening in the past include the Salton / Russel Hobbs corporation, now part of Spectrum Brands; the Westinghouse brand which seems to universally appear on the worst electronics imaginable, Sylvania, Emerson Radio, and quite a few others.

Funai Corporation was originally the manufacturer on many of these junkers, but in recent years they’ve lost traction since a retailer can just shop around themselves for the lowest prices on random Chinese manufacturing.

Mamma Mixer!!

This is the big mama of all audio mixers.
It’s kidproof. I’ve witnessed kids climbing right on the fader knobs and causing no harm.
Holy wow. See my hand there? That’s not a small hand. That’s a biiiiig fader.

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Like a funky British audio console I worked on at a BBC World Service studio, this mixer just uses the control surface faders to set a gain control voltage to some offboard voltage controlled amplifiers (VCAs).

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I’ve just kinda overlooked this thing for years until today when I had to open it to change a set of captive, vandal resistant headphones screwed through it. What I expected was to find some cute little linkage connecting to a set of small faders. What I found puts Penny & Giles faders to shame!!!

Warning!! Engineering porn ahead!! Have some lint free wipes, DeOxit Fader Lube, mild dish soap and water ready before clicking…….

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Apple iOS: “Try again in 40 years…”

 

Whoop whoop, big surprise, there’s a BUG in this operating system! Apple iOS on the iPad, iPhone, iPod Touch, and iToilet have all been reported to do this once in a blue moon. Apparently it’s a result of a login failure followed by the system realtime clock resetting back to 0 seconds after Jan 1, 1970, 00:00:00 UTC.

At least on the desktop Mac OS X, a warning is thrown and sensible measures are taken to prevent meltdown when the system time gets lost like this. On the iBaubles, though, you may be faced with this: “iPhone / iPod / iPad is disabled, try again in 23,000,000+ minutes (about 40 years)”.

This would indicate that the login system is basically just doing something like this: if the password entered is invalid, it adds 60 seconds (or whatever) to the current time in seconds since January 1, 1970, then sets that as a deadline before which you cannot login again. Unfortunately this is stored in nonvolatile storage somewhere, but the time can still be lost by a loss of power, and no sanity check is present to reset the timeout if the system time is lost. (A much better method would be to just check the kernel’s register for system uptime!!) Since NONE of the Apple devices have user-replaceable batteries, this wouldn’t exactly be defeating the security granted by slowing down an attacker trying multiple passwords on the device.
IMAG4769_1[1]

 

The solutions:

* Get the time set on the device again. Either move into range of a WiFi network the device previously recognizes, or into range of a cellular signal in the case of an iPhone or 3G/4G connected iPad. Upon reestablishing connection, the device may reset its clock and allow login again.

* Reset completely and restore from DFU mode. You will lose anything stored on the device…. but it’ll be unbricked.
DFU mode instructions here.

Gee, is it any wonder why I prefer Android? 😉

 

A hot button issue.

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Q. How much current can you switch with the contacts of a Suzo-Happ Ultimate Arcade Pushbutton?

A. A little less than this. ????

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Don’t overcook a PDIP.

Microwaving a dead ULN2803 PDIP: https://youtu.be/zn3EdQsz3uw

Gotta wonder how a cerdip part would fare — at least it wouldn’t keep burning.

This one suffered a bad output that disabled functions of a museum exhibit I was working on, and I wasted a few minutes trying to figure out why…. Then a minute more precisely cutting out some wire to form a perfect 2450 megacycle dipole, putting the chip in the middle…….

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Magic Smoke has vented.

Jellyfishin’, or, pretty lights

If you’ve got an Arduino, a DMX512 control shield, and some lights that are DMX512 controllable, try this effect out. (The variables are called “JellyFish” because I was using it with an American DJ Jellyfish.)

The Jellyfish can be put in a 28 channel DMX mode where each channel sets the brightness of one of its 28 blocks of color or white LEDs.

The effect of running this code should be that you get a cool display of each light turning on then fading out. Every number of iterations set by jellyFishAddRate, one of the lights will be randomly selected and maxed out, then continue to fade back down. It’s a really nice looking effect and would look pretty awesome on a linear array of individually addressable lights. The same effect should work well on other things like addressable LED tapes and ‘smart’ pixels/Christmas lights, etc, with appropriate drive method.

#include <DmxSimple.h> 
// import the DmxSimple library, of course

int jellyFish[28]; // This array will store the brightnesses
int jellyFishBase=1; // dmx512 base address for da fish
int jellyFishFadeRate=19; // Higher = slower
int jellyFishAddRate=84; // same deal
int jellyFishAddCount;
int jellyFishFadeCount;

void setup() {
jellyFishAddCount=0;
jellyFishFadeCount=0;
 DmxSimple.usePin(3); // this is the data output pin on the shield you're using. if you need to enable the transmitter with another pin, don't forget to DigitalWrite it HIGH!

 /* DMX devices typically need to receive a complete set of channels
 ** even if you only need to adjust the first channel. You can
 ** easily change the number of channels sent here. If you don't
 ** do this, DmxSimple will set the maximum channel number to the
 ** highest channel you DmxSimple.write() to. */
 DmxSimple.maxChannel(42);
 // Turn on the lights.
 int i;
 for (i=0; i<28; i++) {
 jellyFish[i] = 255;
}

}

void loop() {
 jellyFishFadeCount++;
 jellyFishAddCount++;
 if (jellyFishAddCount > jellyFishAddRate) {
 jellyFish[random(28)] = 255;
 jellyFishAddCount=0;
 }
 if (jellyFishFadeCount > jellyFishFadeRate) {
 jellyFishFade();
 jellyFishFadeCount = 0;
 }

 int i;
 for (i=0; i<28; i++) {
 DmxSimple.write((jellyFishBase + i), jellyFish[i]);
 }
}

void jellyFishFade() {
 int i;
 for (i=0; i<28; i++) {
 if (jellyFish[i] > 0) {
 jellyFish[i]--;
 }
 }
}

We wore an onion on our belts…

A couple decades ago the ICE Games Cyclone came out. It’s this big round “stop the light” arcade game still produced to this day and installed in almost ALL arcades that have redemption games, as it makes decently good earnings and has no moving parts (other than cooling fans) – nothing to really go wrong other than some little kid running it out of tickets. It uses incandescent lamps, but best I can tell it’s running 12 volt bulbs at 9 volts DC at a very short duty cycle… I’ve never seen one with bulbs out.

Out of curiosity I looked in its manual and found this, the schematic for the lamp driver boards:

cyclone-driver-s

 

I immediately grimaced and was like “wait, what IS all that?”. Well, 1990. That’s what it is.

The left set of chips are 74HCT164 shift registers. The right set are 74HC273 D latches, used to “mute” the lamp outputs while the shift registers are busy being spun around to advance the selected light position, then latch the selected lamp outputs in to the lamp drivers which are ANOTHER layer of parts – oldschool TIP120 bipolar junction transistors.

Nowadays I’d just use a pair of TPIC6595 series chips from Texas Instruments. The TPIC6595, TPIC6B595, and TPIC6C595 are all shift registers with a builtin set of output latches and high current low-side DMOS drivers – the B/C variants have different characteristics to the drivers and are less expensive but lower current. All of them would cheerfully drive an incandescent bulb like they used there, or better yet, LED.

This just proves I’m spoiled rotten.

But we had to say dickety because the Kaiser had stolen our word “twenty”—-

Microphone challenge!

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This is a vandal resistant gooseneck mic made in the UK a couple years ago… Since discontinued because nobody bought them. They lasted too long.

This is what the kids did to it.

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My theory is that someone broke the gooseneck then hammered the mic into surfaces until the head broke open.

This presents a challenge not typically encountered by a radio engineer, how do you come up with an adjustable microphone that can deal with children hanging or swinging from it? (I’ve personally witnessed both.)

Any suggestions? I’m thinking of making a mic boom out of 80/20 components with a mic capsule in a piece of plumbing pipe and a gas shock to support the weight.