most creative / bizarre use of a component for other than intended purpose? - Page 1
Forum section: electronics / general

author: djacobow
author_rank: Super Contributor
timestamp: March 21, 2019, 04:45:49 pm
content: As I get more experience with electronics, I appreciate the need to stay within all the required parameters of a device, if I want a reliable circuit, and the need to stay *well* within those parameters if I want to manufacture a reliable circuit in volume with minimal fuss.But this has made me curious -- for fun -- about pushing parts beyond their ratings or into strange service that you'd never guess from the datasheet. You have any favorite examples of this? The weirder the better!

author: tggzzz
author_rank: Super Contributor
timestamp: March 21, 2019, 05:05:56 pm
content: An AoE x-Chapter writeup...Quotehttps://groups.google.com/forum/#!topic/sci.electronics.design/7Y9qPYSn1k0

author: Andy Watson
author_rank: Super Contributor
timestamp: March 21, 2019, 05:07:55 pm
content: I think Mike already has the winner:http://www.electricstuff.co.uk/electrofun.html

author: nctnico
author_rank: Super Contributor
timestamp: March 21, 2019, 05:12:58 pm
content: One of the designs I worked on uses an RS485 transceiver to inject a tone into a telephone line. We had no space to work with, only a few pins from an FPGA and needed something rugged and simple to do the job.

author: djacobow
author_rank: Super Contributor
timestamp: March 21, 2019, 05:13:28 pm
content: Quote from: tggzzz on March 21, 2019, 05:05:56 pmPoor fishies getting zapped with bright flashes all day long!That's a cool example, though Hill doesn't get full credit, because he's still using the LED to make light. :-)

author: djacobow
author_rank: Super Contributor
timestamp: March 21, 2019, 05:18:09 pm
content: Quote from: Andy Watson on March 21, 2019, 05:07:55 pmSince everything went SMT,fertilityproduction rates have fallen precipitously.

author: daqq
author_rank: Super Contributor
timestamp: March 21, 2019, 05:19:36 pm
content: I needed a fast trigger pulse transmitted from an FPGA to an IGBT driver. The signal was transmitted using an RS485 driver with precise timing. However, if the signal was over a few microseconds, the device would not survive it.So, after playing around with analog watchdogs, flip flops etc. I found out that the simplest solution would be to use a small RF transformer that would be hooked up to the RS485 driver. The transformer would, with a square wave, quickly saturate, thus failing to feed the termination resistor on the other side, thus naturally limiting the length of the pulse, thus preventing me from fumbling up the FPGA configuration in a destructive way. Bonus: Galvanic isolation!

author: RoGeorge
author_rank: Super Contributor
timestamp: March 21, 2019, 05:39:41 pm
content: Does any of these qualify?- Peltier elements to trigger a tactile thermal illusionhttps://hackaday.io/project/6577-dune-pain-box-a-hackers-replica- Intentionally breacking a MOSFET in order to lower its Vghttps://hackaday.io/project/16616-your-mosfet-is-not-good-enough-then-modify-it- Using ON/OFF relays and DC motors to create a variable flashing light bulb from DChttps://hackaday.io/project/26191-entries-for-the-flashing-light-prize-2017

author: Tomorokoshi
author_rank: Super Contributor
timestamp: March 21, 2019, 06:43:41 pm
content: When it comes tosuccessfulapplications, using an incandescent lamp to stabilize an oscillator.

author: CJay
author_rank: Super Contributor
timestamp: March 21, 2019, 06:46:30 pm
content: Friend of mine discovered that common electrolytic capacitors fit the barrel and fire from .22 caliber air rifles, does that count?

author: Wolfram
author_rank: Frequent Contributor
timestamp: March 21, 2019, 07:29:52 pm
content: An LM317 used as a radio transmitter surely qualifies:https://www.qsl.net/qrp/tx/317-tx.htm

author: coppercone2
author_rank: Super Contributor
timestamp: March 21, 2019, 07:36:08 pm
content: DIP make good spacers when you rip the legs off

author: djacobow
author_rank: Super Contributor
timestamp: March 21, 2019, 07:56:08 pm
content: Quote from: Wolfram on March 21, 2019, 07:29:52 pmYes! I was just thinking about this: can I get a regulator to oscillate and thus transmit a radio signal. I think the answer for me would be no, not on purpose, anyway. But I suspected someone smarter could pull it off!

author: jmelson
author_rank: Super Contributor
timestamp: March 21, 2019, 08:13:47 pm
content: Quote from: djacobow on March 21, 2019, 07:56:08 pmMany years ago, there were memory boards on S-100 systems that had oscillating regulators. I guess it had to do with lots of decoupling caps on the memory array and maybe not enough on the unregulated input. You could hold a transistor radio near it and hear it hiss. My solution was to take all the regulators out and feed the motherboard regulated +5 V.Jon

author: bd139
author_rank: Super Contributor
timestamp: March 21, 2019, 08:17:36 pm
content: I used 1 ohm 1/8W carbon film resistors as igniters for model rockets as they were cheaper and more reliable than the official product to do the job.Also I used a big electrolytic capacitor as a plumb bob once.

author: EEVblog
author_rank: Unknown
timestamp: March 21, 2019, 08:59:21 pm
content: Not an electronic component, but intended for electronics use.I once shock and vibration tested sanitary pads as a shock absorbing material for a crystal oscillator.(they weren't terrific BTW)

author: EEVblog
author_rank: Unknown
timestamp: March 21, 2019, 09:02:40 pm
content: Quote from: bd139 on March 21, 2019, 08:17:36 pmWe used to use a through hole resistor in a little pocket on the side of a flotation bag for a sonobuoy. After a pre-set time floating on the ocean the resistor would burn through the bag and sink the buoy.Also used a resistor with a string around it to hold back the striking pin for the air canister that inflated the bag, heating up the resistor burned the string.

author: bsudbrink
author_rank: Frequent Contributor
timestamp: March 21, 2019, 09:58:36 pm
content: DRAM as image sensor (when it was first done in 1974):More info:http://wsudbrink.dyndns.org:8080/cyclops/index.html

author: Gyro
author_rank: Super Contributor
timestamp: March 21, 2019, 10:06:08 pm
content: Quote from: Andy Watson on March 21, 2019, 05:07:55 pmFrom the crazing on that Rifa cap I think they're in for a bigger bang than they expected.

author: electromotive
author_rank: Regular Contributor
timestamp: March 21, 2019, 10:19:11 pm
content: Homemade rotary phase converters -- a simple yet elegant solution for running 3-phase machines on standard 240v.

author: Psi
author_rank: Super Contributor
timestamp: March 21, 2019, 10:33:57 pm
content: One some metal enclosures the sides are tapered. So the top is bigger than the bottom.For example, side view---------/ \-----------I have seen PCB mount phono jacks used on the side of these cases. (guitar effects pedals that sort of thing)The jack is both chassis mounted to the sides and TH soldered to an internal PCB.This creates a problem because the case side angle is not 90deg to where you want to put the PCB in the case. eg The PCB wants to sit at an angle.To solve this problem i saw someone put non-connected SMT resistors/caps under the edge of the jack socket so it sits angled on the PCB and counteracts the case edge angle so that the PCB sits flat in the case.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 21, 2019, 10:50:00 pm
content: Jim Williams famously applied high voltage to bipolar transistors in a controlled way in order to generate very fast pulses. That also works for applications requiring not so fast pulses, in which case transistor selection and circuit layout are no longer critical. I made a flashing LED circuit for a small solar panel that way (for a visual indication that it is in fact generating electricity), uses well under a milliamp to make a yellow LED flash bright enough to be seen even in direct sunlight. That was about 20 years ago and the indicator still flashes!And while not really a component, I managed to make art out of some FPGA mining code I found online. Long story short, I was using that code to help a friend of mine and I wanted to find an interesting picture to post on Facebook so that my other friends can see what I did. I opened the code in Vivado (schematic view) and started coloring the lines in order to make the picture look better - in other words make it into art! Not only did some code intended to help an artist become art itself, I used Vivado as a coloring book...

author: RoGeorge
author_rank: Super Contributor
timestamp: March 21, 2019, 11:13:56 pm
content: 555 timer as an AM radio receiverhttps://hackaday.com/2011/02/25/hear-that-its-a-555-timer-am-radio/

author: nctnico
author_rank: Super Contributor
timestamp: March 21, 2019, 11:16:21 pm
content: 555's also make a nice PWM controller chip. And with an extra transistor you can have current limiting too.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 21, 2019, 11:46:58 pm
content: Quote from: nctnico on March 21, 2019, 11:16:21 pmThat's one of its intended uses. The 555 and 7400 contests had all sorts of strange uses for those chips.Ever tried using an 8 bit microprocessor (not microcontroller) as a binary counter with no other active component except the clock source and indicator LEDs? Julian Ilett did.

author: amyk
author_rank: Super Contributor
timestamp: March 22, 2019, 12:18:47 am
content: Ceramic decoupling capacitors on an MCU board used as a diagnostic beeper controlled by some software that repeatedly woke and put the processor to sleep at the appropriate frequencies.

author: David Hess
author_rank: Super Contributor
timestamp: March 22, 2019, 12:50:55 am
content: 1. Using transistors as low leakage and fast diodes.2. Using transistors as zener diodes.3. Using transistors as noise diodes.4. Using a single transistor to generate a negative voltage.5. Using an optocoupler to generate a negative voltage.6. Using a CMOS hex inverter in reverse (inputs and outputs are inputs, power pins are outputs) as a synchronous bridge rectifier.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 22, 2019, 01:39:44 am
content: A German company who made turbo vacuum pumps made use of a Switchmode power supply controller IC to source drive pulses for their high speed polyphase motor.The IC could produce a pulse train which started out with a low duty cycle to get the motor turning, then the duty cycle increased, until the correct speed was obtainedIt "thought" it was regulating a Power supply voltage, but was in fact, stabilising the motor speed.There was a lot more to it than that, but it is too long ago, & I didn't take notes.Telecom Aust used sanitary napkins to wipe the insides of waveguides.Their predecessor, the PMG Dept, used fishing rod blanks to push cables thru crowded cable ducts.The Army allegedly used condoms to keep moisture out of the muzzles of artillery.I used some small circular PCBs from some forgotten audio project to fill holes which had been burnt in the SMPS PCB of a Picture Monitor in a quite spectacular blow up.After epoxying them in, their existing tracks lent themselves almost perfectly to mounting the components which had been vapourised in the "big bang".The delay timers in one old Broadcast Transmitter used "electric jug" elements combined with a bimetallic strip.It the element failed, they were available at the nearest hardware shop.

author: coppercone2
author_rank: Super Contributor
timestamp: March 22, 2019, 04:52:18 am
content: i think it was standard procedure to issue prophylactics for beach landing operations in the marine corps to allow the rifle to get through the beach head without being flooded

author: helius
author_rank: Super Contributor
timestamp: March 22, 2019, 05:08:33 am
content: Quote from: coppercone2 on March 22, 2019, 04:52:18 amSam Fuller's "The Big Red One" shows this being done. Fuller was present at the Normandy landings and it was from his own experience.

author: GopherT
author_rank: Contributor
timestamp: March 22, 2019, 06:04:15 am
content: I've been using a 12V/15A transformer as a door stop for the past 15 years. Slides well on the sidewalk when I push with my foot but it never lets the door move. Even with all the copper crooks around here, nobody ever tried to take it.

author: CJay
author_rank: Super Contributor
timestamp: March 22, 2019, 12:35:14 pm
content: Quote from: vk6zgo on March 22, 2019, 01:39:44 amThat bi-metallic thermostat is a work of art, it's been used in so many applications.There's a great radio documentary about it featuring the inventor, John Taylorhttps://www.bbc.co.uk/programmes/b0b42z87

author: Urs42
author_rank: Unknown
timestamp: March 22, 2019, 12:41:44 pm
content: Not really a component but i had to have a landline phone contract for reasons, there was nothing connected to that line. I did use that line to power some DC fans and other things. At least i was getting something useful for the money...

author: bd139
author_rank: Super Contributor
timestamp: March 22, 2019, 12:42:38 pm
content: That’s not a bad idea actually

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 22, 2019, 01:04:39 pm
content: Quote from: CJay on March 21, 2019, 06:46:30 pmCharge them up first for an extra zap on impact, like a stun gun.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 22, 2019, 01:53:16 pm
content: Quote from: NiHaoMike on March 21, 2019, 11:46:58 pmIt's arguably more "off brand" to use a 555 as a peak current mode controller:https://www.seventransistorlabs.com/Images/555%20Boost.pdfbut really it's just using it for what it is.Indeed, do see those contests for a level well beyond what'll get covered in this thread.Quote from: vk6zgo on March 22, 2019, 01:39:44 amThis too, isn't especially "off brand" when you consider that a motor is just a rotating transformer.Now, a full VFD, can get quite complicated indeed when you include features like torque and inertia control, jog and so on, but the core could still be a PWM something or other if you really wanted. (I've taken apart 70s-80s VFDs chock full of RTL gates; lord knows what all they were doing in there.)Tim

author: soldar
author_rank: Super Contributor
timestamp: March 22, 2019, 05:35:08 pm
content: Quote from: EEVblog on March 21, 2019, 08:59:21 pmI have used the "artificial cork" they use for wine bottle stoppers these days. They are very good for this type of purpose. And always a good excuse to buy wine

author: soldar
author_rank: Super Contributor
timestamp: March 22, 2019, 05:42:48 pm
content: Quote from: Urs42 on March 22, 2019, 12:41:44 pmA phone line cannot supply more than about 1W so I cannot see how it could possibly power "fans and other things".

author: soldar
author_rank: Super Contributor
timestamp: March 22, 2019, 05:45:10 pm
content: Quote from: GopherT on March 22, 2019, 06:04:15 am12V/15A is the correct spec for this purpose. Anything else will not work as well.

author: Urs42
author_rank: Unknown
timestamp: March 22, 2019, 06:26:01 pm
content: Quote from: soldar on March 22, 2019, 05:42:48 pmNot at the same time, but it was possible to light up a LED Xmas light string get a 200mm "PC" fan to turn, i think it did not run at full speed, this was more than 20 years ago.

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 22, 2019, 07:10:16 pm
content: Quote from: amyk on March 22, 2019, 12:18:47 amAlong a similar idea, many ESC's for brushless motors will use the motor itself as a beeper to indicate status and configuration info.

author: Dr. Frank
author_rank: Super Contributor
timestamp: March 22, 2019, 07:20:59 pm
content: Our former senior engineer, Mr. Kr., once created the expression 'angst capacitor'.That's a capacitor designed in by too an anxious engineer into an automotive electronics for passenger vehicles, rated with high capacitance like 2200uF and high voltage like 25V.These too high values should let the electronics survive at low battery during ignition, and jump start, which is loading the 12V car battery briefly with van battery voltage of up to 28.8V, when car shall be rolled out of ship after weeks of transport, having an empty battery.Instead, a 1000uF/16V capacitor should be used, as this nominal DC voltage includes some ac overhead of formation of the electrolyte, about a factor of 1.5. Remember, that during the formation process the oxide thickness of the anode is created, by a high formation current. The supplier had to guarantee to withstand 2min of 28.8V.It's getting even more strange.. This low voltage rated elco would also serve as a zener diode, during load dump pulses. These are short inductive over voltages in the car power network, when heavy loads were switched, like the starter/generator, HVAC and steering aid motor.Usually, a suppressor diode would be used to clamp the induced energy at about 30V.A 16V elco would draw excess formation current at these higher over voltages, therefore behaving like a zener, or suppressor diode.That senior is long retired, so the engineers now chose less dangerous values.Frank

author: RoGeorge
author_rank: Super Contributor
timestamp: March 22, 2019, 07:21:32 pm
content: Here we have regulations against using landline phone lines other than intended.You are not allowed to connect any other device to a landline phone (except a landline approved phone that fulfills all the landline phones regulations).

author: jmelson
author_rank: Super Contributor
timestamp: March 22, 2019, 07:36:16 pm
content: All Haas machining centers use a stove-top "cal-rod" heating element as a braking resistor on the spindle drive. They put it in a perforated cage for heat removal.Lots of VFD manufacturers sell fantastically overpriced braking resistors (in the $200 range) to people who don't know better.Jon

author: unitedatoms
author_rank: Frequent Contributor
timestamp: March 23, 2019, 12:17:01 am
content: I once made a variac kind of driver for incadescent bulb using thyristor, xformer and small bjt in avalanche mode, running from mains voltage. Similar to this article.https://electronics.stackexchange.com/questions/98066/how-does-this-bjt-transistor-work-without-any-connection-to-its-base

author: vk6zgo
author_rank: Super Contributor
timestamp: March 23, 2019, 12:30:00 am
content: Quote from: T3sl4co1l on March 22, 2019, 01:53:16 pmYes, & the upside for me was that I could find the full specifications for the device they did use, supplementing the minimal information available from the umpteenth generation photocoipy that took the place of a Service Manual.A special device would have been much more difficult.The motor drive was an interesting thing, there were 4 "phases", with some big fat power BJTs being switched in turn to create the revolving field.Hall effect sensors provided feedback as to motor position, speed, etc.The motor & pump could not be separated without a lot of work (I had that on good authority from the Mechanical Engineering guys), so testing entailed jury rigging a bunch of car headlight bulbs as a test load.The driver passed these tests only to goBang!when we connected it to the real thing.I thought I must have been doing something wrong, & went through the same routine again------Bang!Turns out there was a mechanical fault in the pump, so it couldn't turn.These things are very "touchy" about being used outside their proper vacuum environment, so we didn't take the top off.Of course, that meant we couldn't see the damage through the little window in the lid.

author: Canis Dirus Leidy
author_rank: Regular Contributor
timestamp: March 23, 2019, 01:10:40 am
content: Quote from: RoGeorge on March 21, 2019, 11:13:56 pmPfff. Real men use7400К155ЛА3 and catch harmonics with FM-receiver:P.S. Or you can use NAND IC as FM detector:http://radionet.com.ru/shem/shem487.htmlP.P.S. And real programmers use whole PDP-8:

author: David Hess
author_rank: Super Contributor
timestamp: March 23, 2019, 03:57:43 am
content: Quote from: bd139 on March 21, 2019, 08:17:36 pmCarbon composition resistors had their off-label uses also. Low value 1/8th watt ones make good overload resistant fuses. Large value high wattage carbon composition resistors are useful as inductor winding forms with built in leads.Another use I have had for high value resistors is as a substitute for a binding post to physically anchor a circuit connection.

author: Brumby
author_rank: Unknown
timestamp: March 23, 2019, 04:17:22 am
content: Would you call an IBM 3203 printer a "component"? (Itwaspart of a System 370 installation.)If so, I worked worked out a sequence of printed characters to create a musical scale from the impact of the print hammers. Put together two tunes: "Whistle while you work" and "We wish you a Merry Christmas".The IBM field engineer liked it. My manager smiled ... and told me not to do any more.

author: GlennSprigg
author_rank: Super Contributor
timestamp: March 23, 2019, 11:57:36 am
content: I'm not sure if this equates to the 'OP's postulations, but once, I was involved with a machine,that was basically a 'Heater', that was drying manufactured Toweling after the dyeing process.It was larger than a shipping-container, and was fully encased in grounded stainless steel.1st point of interest, is that it used (i think, from memory) 35,000 Watts of RF as the heat source !!2nd point of interest, is that when you opened any of the 'doors' on the sides, it was internallybrilliantly lit, with many bare fluorescent light tubes, held in place with spring-clips, & no wiring !!Not sure how Oc-Health-Safety would grade all that nowP.S. I do not remember what the frequency was...

author: joeqsmith
author_rank: Super Contributor
timestamp: March 23, 2019, 05:03:53 pm
content: Quote from: Dr. Frank on March 22, 2019, 07:20:59 pmInteresting is I would consider a load dump to be a very wide high energy transient. We called the case where the engine was running and the cables were removed from the battery a load dump. The charging system back then would reach well over 30 volts. Some of the semiconductors were designed specifically for it. Times change and it sounds like it now has a new meaning in automotive.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 23, 2019, 08:56:40 pm
content: I think he misspoke about inductive transients versus load dump as such, but meant load dump?Tim

author: Circlotron
author_rank: Super Contributor
timestamp: March 23, 2019, 10:10:54 pm
content: An LM317 adjustable voltage regulator makes a surprisingly good class A audio power amplifier.https://www.diyaudio.com/forums/solid-state/12377-4-harmony-9-watt-class-amp-using-voltage-regulator-ic-3.html

author: Kleinstein
author_rank: Super Contributor
timestamp: March 24, 2019, 10:39:39 am
content: At the university I passed AC current through solar cells to produce sound. Not very effective but it can tell something about the solar cells if one "listens" (measures) carefully.A classic one is a non working computer as a door-stop.Another classic is the broken Dell cup holder (CD player tray).

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 24, 2019, 12:37:17 pm
content: Quote from: Kleinstein on March 24, 2019, 10:39:39 amI have actually seen a symbol for "Do not use CD drive as cup holder" on a few servers I worked on. I guess some users really are that stupid...

author: TERRA Operative
author_rank: Super Contributor
timestamp: March 24, 2019, 01:52:08 pm
content: Quote from: David Hess on March 23, 2019, 03:57:43 amJaycar did this for an inductor in an amplifier kit.

author: BrianHG
author_rank: Super Contributor
timestamp: March 24, 2019, 02:57:27 pm
content: Using a panel meter's arm as a microgram balance scale:https://www.eevblog.com/forum/projects/mg-scale-interesting-effect/msg2292177/#msg2292177

author: Gribo
author_rank: Frequent Contributor
timestamp: March 24, 2019, 04:27:42 pm
content: A Xilinx Spartan 5 as an analog filter, the RTL was generated by genetic algorithm.http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=6691182CC83AE8577D7C44EB9D847DA1?doi=10.1.1.50.9691&rep=rep1&type=pdf

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 24, 2019, 06:29:31 pm
content: You can use standard vacuum tubes at low plate voltages (like 12V) and even get significant current through them. It's called space charging and you can build some neat things with jellybean audio tubes (though there were even special tubes designed for space charging used in portable radios). You can even switch relays and drive LEDS at moderate current (watch it, even at low voltage the current can be high enough to pop things in certain conditions, but it won't be the tube).http://www.junkbox.com/electronics/lowvoltagetubes.shtmlhttps://en.m.wikipedia.org/wiki/Space_chargeHowever, normal audio and radio/tv tubes will work with experimenting and tinkering, though space charge circuits are very different from normal tube circuits such as having positive grid bias. (Won't work as well as the actual space charge tubes probably, but as I said you can still build useful quirky stuff).https://www.eevblog.com/forum/projects/all-tube-automatic-led-lampnight-light/msg1008013/#msg1008013(I have no schematic sorry, but I should get to posting one. It's incredibly simple, and I managed to get away without an LED limit resistor, but you can play around with different tubes and whatnot for more current).

author: janoc
author_rank: Super Contributor
timestamp: March 24, 2019, 06:39:57 pm
content: I have used HIN232 (MAX232 clone) for its charge pump in order to get +10/-10V out of +5V to drive LCD shutter glasses.

author: Dr. Frank
author_rank: Super Contributor
timestamp: March 24, 2019, 07:13:09 pm
content: Quote from: joeqsmith on March 23, 2019, 05:03:53 pmWell, the explanations of the origin of such Load Dump pulses varies. Often, it is only linked to the loose connection to battery fault.I remember, that I specified such special Load Dump pulses for electrolytic capacitors, like 'withstand 10 pulses of 30V (?) in 1h (?)', or so, as to simulate that loose connection.But the battery fault is only one example, 'Load Dump' literally means dumping offanyelectrical load, which is carrying heavy currents.(At the moment, I can't check ISO 7637, if the origin is described in detail, maybe tomorrow.)Even the headlamp main beam might switch off about 10A in the on-board supply, and a servo motor switches 30..40A as well.The generator then creates spikes/pulses, caused by its own inductance, or by the limited decay time of the primary generating magnetic field.Normally, the battery soaks up these voltage pulses, but due to the inductance of the wire harness, the pulses can anyhow first spread into other electronics.Another effect might occur directly from the inductive consumer, as its inductive spikes might crosstalk into the wire harness.But that effect is usually not covered by the Load Dump norm.Frank

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 24, 2019, 08:06:01 pm
content: Quote from: janoc on March 24, 2019, 06:39:57 pmThe HC-SR04 also uses a MAX232 as a boosted driver.

author: CJay
author_rank: Super Contributor
timestamp: March 24, 2019, 08:23:15 pm
content: Quote from: janoc on March 24, 2019, 06:39:57 pmI've used as a charge pump for a varicap

author: tszaboo
author_rank: Super Contributor
timestamp: March 24, 2019, 10:07:34 pm
content: When we found out, that those cheap 3mm blue LEDs shoot off the domes, when they are instantaneously grossly overloaded... Then we bought a few hundred. It was a lot of fun. Also, finding out the physics, on how far away can we shoot the plastic dome.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 25, 2019, 12:35:01 am
content: Quote from: NANDBlog on March 24, 2019, 10:07:34 pmNot quite a use, but years ago, we inadvertently wired up some Mains distribution panels (not the big ones, the small ones at the bottom of a 19" rack), using 125v neon indicator lamps instead of 250v.A bunch of us were given the job of removing the incorrect ones, chucking them in a bin, & fitting the right type.As luck would have it, the bin was a bit far away, so it became a competition to try to chuck the redundant neons from a distance.To our surprise, some lamps which didn't make the distance flashed when they made an impact on the concrete floorThe game, of course, then became to see how many we could make flash.These were the standard rectangular ones, with the neon & series resistor enclosed in a red plastic case.I often wondered what mechanism would make the neons flash due to impact alone, with no voltage source.

author: joeqsmith
author_rank: Super Contributor
timestamp: March 25, 2019, 02:04:36 am
content: Quote from: Dr. Frank on March 24, 2019, 07:13:09 pmThe standards we based our tests off were very specific about the load dump. I want to say it was 60V for 10's of ms, or maybe the parts were rated to 60 and we tested at 40. Seems we only had to apply maybe 5 or so pulses. It would be fun to have those standards today. As I remember for example, they showed how to make the generators (which we did). There was a fast inductive switching transient and they called for some specific air conditioner clutch solenoid. The only test we did not build the generator for was ESD. That's been a very long time ago. Things were very crude compared to where we were by the time I left automotive.

author: BrianHG
author_rank: Super Contributor
timestamp: March 25, 2019, 02:36:27 am
content: Using a PIC with comparitor inputs, and a software UART, I did make a proper balanced RS485 transceiver (only using the PIC comparitor input as a true differential line receiver and switching the same 2 pins to output generating a differential line driver.) back in the early 2000's which ran a multi-node temp, humidity sensors + led display & push buttons, at 2400 baud networked through a 8 story apartment building on unshielded phone cables, error free! Cant do that with the UART unless you want to add a RS-485 transceiver IC on each PCB.

author: CJay
author_rank: Super Contributor
timestamp: March 25, 2019, 07:14:17 am
content: Quote from: TERRA Operative on March 24, 2019, 01:52:08 pmMaplin did it for their classic MOSFET amplifier but a resistor in parallel with a coil damps ringing so it's not uncommon to see in some applications (CRT monitors, many had a resistor in parallel with a low inductance coil, the resistors used to fail and the result was visible on screen as a ghosted image of one or more colours).*oops, beaten to it by BLueskull*Quote from: blueskull on March 25, 2019, 01:08:31 am

author: Canis Dirus Leidy
author_rank: Regular Contributor
timestamp: March 25, 2019, 08:23:28 am
content: If you have old diodes or transistors, do not throw them away. You can make a photocell or solar battery from them:

author: alanb
author_rank: Frequent Contributor
timestamp: March 25, 2019, 03:49:25 pm
content: GreatScott used a CPU as a hand warmer.https://youtu.be/Bw2p-Dmn48U

author: langwadt
author_rank: Super Contributor
timestamp: March 25, 2019, 04:10:10 pm
content: Quote from: joeqsmith on March 25, 2019, 02:04:36 amhttp://www.compel.ru/wordpress/wp-content/uploads/2017/05/ISO-16750-22010E-.pdf

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: March 25, 2019, 07:54:43 pm
content: 1.) As I have told already somewhere, I use overage electrolytics in combination with a variac to scare noisy birds away.2.) There was a VERY full mounting plate to which one 1/2cc relay had to be added in immediate vicinity to certain other components. I looked into my stuff and found a strip of perforated sheet metal, which, in combination with two standoff bolts, allowed us to mount it above/between two others.I can only say that to my knowledge, it was the only part of a MECANO set to make it THAT FAR.(Talking about LEO here)

author: joeqsmith
author_rank: Super Contributor
timestamp: March 25, 2019, 11:12:09 pm
content: Quote from: langwadt on March 25, 2019, 04:10:10 pmThanks for the link. I want to say that the standards we used came directly from the big three. This is roughly 30 years before the standard you mention. I remember talking about whole system clamps to handle the load dump but nothing had been implemented. I want to say back then we were not doing anything with bulk current injection. One interesting thing looking at the document you link is they test to -20C. I think we designed for -40 to 85C inside the car and -40 to 125C under the hood. We used 217 ground mobile back then to predict life. A bit too conservative and later the big three worked out PREL which was basically about the time I moved on. Again, it's all a bit of a fog now.

author: HalFET
author_rank: Frequent Contributor
timestamp: March 26, 2019, 01:12:24 am
content: I think my worst abuse of a component so far was to use a full-fledged VFD for 3 phase motors to drive an electroluminescent panel of a few watts.

author: David Hess
author_rank: Super Contributor
timestamp: March 26, 2019, 01:24:49 am
content: Quote from: CJay on March 25, 2019, 07:14:17 amI was only refering to using the resistor has a coil form. Winding an inductor around a low value resistor which damps the Q is still sometimes done for RLC decoupling and load isolation. You can find this in a lot of old through-hole test equipment.

author: SeanB
author_rank: Super Contributor
timestamp: March 26, 2019, 04:56:00 am
content: I was using a mystery TO3 transistor ( no markings on it, out of the used parts bin but was NPN, probably a 2N3055 or a 2N3773, but definitely not a BUX20, as those are not available in the standard TO3 package, but only in the massive high current package with heavy Kovarbase and leads) as a dummy load on a 5v rail, as I had to check it was capable of delivering 10A while still staying in spec.Simple enough, transistor with 3 leads soldered to it, one heavy one to emitter that was bonded to chassis of the equipment, use any of the 84 M4x16 capscrews you had to remove to get the covers off, a thinner one to base leading to the decade box, and then collector was a thick wire soldered to the top hat of the device. In use take a nice clean cup, fill with cold water and drop the transistor in it, and measure current with the AVO8 on the 15A DC range, Dc voltage with the test rack DMM. As the test generally only would be 10 minutes or so, unless you had to adjust settings with another 2 decade boxes, as resistors were select on test and solder into the turret pins on the PCB, a lot more reliable than a variable resistor, but in general you only ran 10 minutes at a time. Water got hot, but generally not to the point of the transistor boiling it.Same transistor survived, even being used to test power supplies, where you went well over 20A for a few seconds.The BUX20 transistors were used in a lamp control, interesting in the power stage used a early optocoupler, and this drove a darlington stage made from a 2N2219A and the BUX20. Badly designed, the transistor was poorly heatsinked ( and not possible to change either without 1 ton of paperwork) so only thing was to select drivers for highest gain and thus lowest saturation voltage. Safety feature ( unintended) was the BUX20 unsoldering itself from the base and emitter wires when it got to 200C case temperature, otherwise lesser transistors tended to just go short circuit, blowing the 20A DC fuse, after blowing the main and spare lamp ( because pilot would switch in spare lamp of course when first went out, and this would blow the fuse on the now short circuit transistor) out. Interesting transistor BUX20, 50A collector current and usable gain at this as well, just really expensive, and only was beaten by power mosfets recently, just do not believe the power dissipation, hard to do without water cooling.https://www.comsetsemi.com/Datasheet/bux20.pdf

author: johnwa
author_rank: Frequent Contributor
timestamp: March 26, 2019, 07:21:45 am
content: I don't have the link handy right now, but some time ago, a local radio club organised a competition to build a radio receiver using a single active device. One constructor ended up using a vacuum fluorescent display as an "integrated circuit" triode. It worked fairly well apparently...

author: LaserSteve
author_rank: Super Contributor
timestamp: March 27, 2019, 01:32:44 am
content: Back in 1984 or so (9th Grade ) I used a dual filament automotive bulb as a poor man's vacuum tube. Specifically to replace a silicon diode in a home made crystal set. Not exactly as good as Germanium but it beat the Galena detector hands down.I then found the gas filled version made a crude Tungar rectifier, but the fill gas was an Argon/Nitrogen mix, so it didn't last long at high currents.Steve