Electrical Engineering

coding_corgi

00:25

Very quite in here...

Kortuk

01:38

@coding_corgi is quite quiet

coding_corgi

@Kortuk ... I won't ask...

rawbrawb

@Kortuk quit quite quiet?

coding_corgi

01:54

@rawbrawb Uh oh, it's not going be quite, but will it be annoying?

rawbrawb

@coding_corgi for several definitions of "it"

Kortuk

:)

coding_corgi

@rawbrawb it = chat room...

AshRj

02:39

0

Q: Highlighting the Tag Wikis

There have been some discussions (1, 2) on the usefulness and visibility of Tag Wikis. Two concerns that were voiced were : Searchability Visibility I had some ideas on how to improve this. Firstly, why at all? Tag Wikis are an awesome resource. Stack sites' have a lot of expertise and wik...

angelatlarge

04:06

@ThePhoton Are you still around?

Any EE people here?

The Photon

@angelatlarge Ahoy

angelatlarge

@ThePhoton Question: with th 1% th resistor how do you know which end is which?

The Photon

@angelatlarge ???

angelatlarge

@ThePhoton Isn't the tolerance band brown?

@ThePhoton (sorry, you probably wanted some context on that)

The Photon

@angelatlarge Ahhh, I don't deal much with grab-bag parts.

Ohm it out with your DMM?

angelatlarge

04:08

@ThePhoton Take a 1000 ohm resistor 1% tolerance, would it not be brown black black black brown?

@ThePhoton Hmm... I guess that's one way.

The Photon

@angelatlarge So who cares which end is which? Have you been drinking?

angelatlarge

@ThePhoton Hmm.. (cheap beer)

You raise a good point, sir.

But what about red black black black brown?

2K 1% or 1K 2%?

The Photon

@angelatlarge Which bin did you take it out of, the 2k bin or the 1k bin?

angelatlarge

@ThePhoton Riiiight. So ther are no other tricks you know of, I guess...

The Photon

Also, I've never seen a 2% resistor in the wild. 5%, 1%, or 0.1%.

@angelatlarge Isn't there sometimes a bit more space between the tolerance band and the others? But that would depend on having the datasheet for the part...In which case you'd probably know what you ordered.

Oh, or 0.5%, I've used those.

angelatlarge

04:13

@ThePhoton I was looking here:

So 0.5% could be confusing. Green.

The Photon

@angelatlarge Ha! I just googled up the exact same chart.

angelatlarge

@ThePhoton It's the lazy man's chart: first google hit :)

The Photon

Again, notice they drew it with space between the value bands and the tolerance band.

angelatlarge

@ThePhoton Most of my 5% are evenly drawn.

@ThePhoton But the 1% is indeed offset.

@ThePhoton Just ever so slightly. OK.

The Photon

@angelatlarge 546 is not a E-192 value.

angelatlarge

04:16

BTW, I always really hated the metal film resistors: on that blue background it is really hard (for me) to tell what the colors are.

@ThePhoton Hmm.. that's a point.

The Photon

@angelatlarge Does that indicate metal film? At my office there's a drawer of resistors that's been there more than 10 years; some of them are beige and some are blue, nobody ever said the blue ones were special

angelatlarge

@ThePhoton Hmm... I always thought so, but that might be an unjustified assumption on my part. If you search Ebay, all of the metal films ones you find are blue, and all carbon film ones are beige, so I assumed that was a natural law.

The Photon

04:34

@angelatlarge Quick browse of Digikey suggests you are right---blue tends to indicate metal film, beige tends to indicate carbon film....

Anindo Ghosh

05:12

@ThePhoton Just jumping in here: With the current breed of eBay sellers / Chinese manufacturers, the norm is Blue = more expensive, Beige = less expensive. I know for a fact that I have blue resistors that are carbon, not metal film. I also have green through-hole resistors that turned out to be powdered carbon inside, not film - but very good precision and stability. I don't even know what type they officially are, but they're cheap.

@Angela For machine intelligence of TH resistors, we used to have a device in a lab that looked like a checkout counter barcode scanner - The system it used was to check for offset as well as check for series corresponding to the ostensible precision as read from band. Occasionally it would refuse to read a resistor, error message "Measure Manually".

user61389

Morning!

angelatlarge

@AnindoGhosh Hi Anindo. Not sure how that is supposed to help :)

@CamilStaps Hello, earthling

The Photon

@angelatlarge If you believe him, he has a surplus machine to sell you!

angelatlarge

@ThePhoton I see. Hm.

Anindo Ghosh

@angelatlarge You'd want to use the same logic: This is how it goes: First check for one band being slightly offset from the others.

Then assume that to be the tolerance band. Read the remaining bands. Compute a value on the basis of those latter bands. Based on tolerance, the resistor will have to fit into E6/E12/E24/E48 and so on. Check against the relevant E-xx table of values. If the color bands + tolerance computed so far matches (with statistical "confidence" figure generated from the colorimetry code), publish that as the value.

If it does not match, assume the tolerance band to be at the other end (or no tolerance band if only 3 bands are detected). Go through above compute + table lookup process.

If that too does not provide an expected result, or if the colorimetric confidence is too low (below 50%), then report "Measure Manually".

@ThePhoton No, that machine, if I still had access to it, would probably be a vintage, and sell for zillionzzz.

angelatlarge

05:22

@AnindoGhosh Yes, I was planning to do something similar to that: extra offset, sanity check, etc. But the confidence measures are hard to generate, and I am having some trouble with color identification anyway.

Anindo Ghosh

@ThePhoton I read that it was patented to someone in Delhi University, though, so I can do a patent search.

@angelatlarge Confidence statistics for colorimetry... Been there done that. 2 cheap techniques that I know of.

angelatlarge

@AnindoGhosh Let's start with a simple color decision algo

The Photon

@AnindoGhosh I gotta admit my colorimetric confidence gets pretty low when the bands get into blue purple grey white territory.

Anindo Ghosh

1. Use an RGB LED, illuminate the target with pure red, then pure green then pure blue, capture result from each. That'll eliminate a lot of "auto-white balance" and extraneous reflected light contamination.

angelatlarge

I have one but like I said not very good.

@AnindoGhosh That isn't an option. :(

Anindo Ghosh

05:25

or... 2. Use a known white LED to illuminate, and run it through a calibration cycle of around 100 actual targets (whose colors you know by multimeter ohm reading), and store those calibration stats.

The Photon

@AnindoGhosh I assume your machine predates the existence of white LEDs though.

Anindo Ghosh

@ThePhoton Blue purple aren't problematic. Grey white are a mess because any white balance can achieve neutral, but there's no visual benchmark for "this is whiter, so it must be white".

The Photon

@AnindoGhosh I meant I can never remember what number does purple stand for.

Anindo Ghosh

@ThePhoton The lab machine predated RGB LEDs. It used a camera flash kind of thing which needed replacing once every 3 months.

The Photon

I can remember ROY G BIV but does the purple band correspond to indigo or violet?

And who wants to count up to 8 when you can just throw the unknown resistor away and pick one out from a properly labelled bin or baggie?

Anindo Ghosh

05:28

@ThePhoton The RGB and the White LED techniques were not with reference to the resistance reader, but just a simple print aging detection system for fine art photo prints.

@ThePhoton Indigo is pretty close to blue, purple has a greater red component.

@ThePhoton Well, today I'd just trash it or measure it, but back in 1986, those resistors were considered expensive by college lab standards. This is an Indian college lab we're talking of, by the way - any expensive gear was invariably a one-time bequeathal by an alumnus.

@ThePhoton I remember the excitement when a former student had gifted the lab a low power red laser.

The Photon

@AnindoGhosh I was kind of wondering about why the machine existed? In Indian economics wouldn't make more sense to hire somebody to sort your bag of resistors into separate bins instead of build a fancy machine with sales potential of a few hundred around the world? And if you're going to build a machine, why not just an ohmmeter with a socket that fits axial-lead resistors?

Anindo Ghosh

@ThePhoton It existed because it had been invented by one of the Univ professors.

The Photon

@AnindoGhosh Like a HeNe tube?

@AnindoGhosh I mean, why invent it?

Anindo Ghosh

@ThePhoton A really small percentage of inventions ever get commercially exploited. They build up a patent portfolio which helps with cred :-)

angelatlarge

@AnindoGhosh Do you think I could color-balance the image correctly by looking at the leads?

Anindo Ghosh

05:35

@ThePhoton Actually come to think of it, I would not be surprised if the uni had made money by actually licensing out that invention.

The Photon

@AnindoGhosh Also, University professors don't get paid to think about sales potential.

Anindo Ghosh

@angelatlarge Hmm, there's a fairly high chance that the leads will be a neutral - EXCEPT if the copper has peeked through.

angelatlarge

BTW: really? Yellow resistors?? WTF?

Anindo Ghosh

@ThePhoton That's not so. My dad was an academic half his working life, and he's got a patent portfolio that is scary as hell - and several of them are commercialized.

angelatlarge

@AnindoGhosh Have you ever seen that?

Anindo Ghosh

05:37

@angelatlarge Wait wait wait let me check my bins, if I don't have yellow, I want some.

angelatlarge

@AnindoGhosh I think the two points are orthogonal. They don't get paid to think about commercial potential, but they often do so anyway :)

Anindo Ghosh

@angelatlarge Well, all projects funded by the Council for Scientific and Industrial Research (Govt of India) must meet marketability potential... And CSIR is a huge fund source for government institutions including universities in India.

@angelatlarge OK the closest I have to that is one with a light beige, not an actual yellow.

Anindo Ghosh

06:03

I'm looking for suggestions on how to harvest power from a piezo bender sufficient to flash an LED, not periodically but whenever there is enough stored energy for a flash. I need to be filtering the piezo's signal to be within a particular passband (15khz to 100 KHz, more or less). Q of filter need not be high.

jippie

06:18

good morning

@angelatlarge because it doesn't exist as a E24 value?

angelatlarge

@jippie Hallo

@jippie Sorry?

jippie

@angelatlarge Same as this remark:

2 hours ago, by The Photon

@angelatlarge 546 is not a E-192 value.

angelatlarge

@jippie OK. But you replied to the brown black black black brown message.

jippie

06:39

For deciding which color a band is, you can use a smart'ish algorithm from the color values you have. A self learning algorithm. Here it is used for spam filtering, but you can make it classify color bands too. drdobbs.com/architecture-and-design/…

angelatlarge

@jippie I was really hoping to avoid all this training stuff...

jippie

just make 14 buckets: black, brown, ... silver

angelatlarge

@jippie Current results are less than impressive though: i.imgur.com/cNgULU6.png

jippie

you can train it yourself with couple resistors. You don't have to ship the training code with the actual app.

angelatlarge

@jippie Oh, and BTW: silver and gold are... I don't even know what they are. Shiny grey and shiny yellow.

jippie

06:42

bayesian filtering is a very quick and accurate learner.

angelatlarge

@jippie Yeah, I've written some linguisics stuff for that. Maybe that is the way to go.... Ugh.

jippie

you just have to figure out a way how it will understand that a 255.0.0 is red and 254.0.0 is read too ;o)

of course you don't have to use full resolution.

angelatlarge

@jippie ?

jippie

and of course you can make the user train the thing when a resistor isn't recognized. better than @AnindoGhosh's measure manually option in my opinion.

in your image the colors are correct, but the decision isn't quite ready for production quality code.

angelatlarge

@jippie You don't say!

@jippie I might try to tweak the existing classifier before I give up and move to a training algo

jippie

06:48

or you can make an upload button, which uploads the image to a webserver and you type the values yourself in response!

angelatlarge

@jippie Yeah, I was thinking the exact same thing: there needs to be "send us the stuff that didn't work" button.

With a 1 cent refund, a la Donald Knuth

jippie

@angelatlarge no don't do that. Someone will figure out how to earn lots of money with bad resistors.

angelatlarge

@jippie Well Mr. Knuth switched to virtual currency some years ago.

jippie

o. don't know this knuth character

angelatlarge

@jippie And as of now, I don't have a very good confidence in my classifier algo anyway

@jippie Big name in Algorithms

Donald Knuth

Donald Ervin Knuth ( ; born January 10, 1938) is a computer scientist and Professor Emeritus at Stanford University. He is the author of the seminal multi-volume work The Art of Computer Programming. Knuth has been called the "father" of the analysis of algorithms. He contributed to the development of the rigorous analysis of the computational complexity of algorithms and systematized formal mathematical techniques for it. In the process he also popularized the asymptotic notation. In addition to fundamental contributions in several branches of theoretical computer science, Knuth is the ...

jippie

06:53

@angelatlarge don't get all depressed so quickly. Once it works on Android, we'll port it to AVR

angelatlarge

@jippie :) And a VAX. And then an abacus

@jippie First you'll have to debug @coding_corgi's camera connection :)

jippie

@angelatlarge no I don't, @coding_corgi changed the controller's ID. There is no support.

angelatlarge

@jippie That's what you say now

jippie

Why haven't I been upvoted while I was asleep? I left some very good answers yesterday.

angelatlarge

@jippie Well, @AnindoGhosh has been away, I've been Android programming. @coding_corgi changed the controller ID, @Peter J has been editing, @CamilStaps.. found a girl, maybe? Is there anyone else?

user61389

06:59

@angelatlarge oh shut up :P

angelatlarge

@jippie Oh, guess not.

@jippie Are you sure that Dr. Dobbs (I can't believe that they still exist!) is applicable here?

jippie

@angelatlarge Girls don't speak C18 nor SPI, so @CamilStaps can't communicate with them

10

angelatlarge

@jippie If I star that will you call me predictable again?

@jippie I don't want to be predictable

jippie

@angelatlarge didn't see that coming

angelatlarge

@jippie I want to be special and unique, just like everyone else

jippie

07:03

@angelatlarge not 1 on 1, but the algorithm can be used. Needs a bit of thinking though.

angelatlarge

@jippie That thinking stuff is hard after a few beers

@jippie BTW, what does a hollow start mean?

user61389

@angelatlarge I starred it too, now you aren't unique anymore!! :)

jippie

context?

angelatlarge

@jippie Right side of the screen

jippie

give me my star back!

user61389

07:04

@jippie you want me to cancel your stars?

angelatlarge

@jippie It is mine now

jippie

@angelatlarge huh?

angelatlarge

@CamilStaps Still drunk with all that power

@jippie OK, "Maybe you are smarter than me" is starred with a hollow star for me. Everything else has a normal star.

user61389

@angelatlarge yeah that's because it's pinned

angelatlarge

user61389

07:06

It stays on top.

angelatlarge

@CamilStaps Is that another one of your "I've got the power" tricks?

user61389

@angelatlarge I didn't do that, but I got teh powerz to do that yes :)

angelatlarge

►

jippie

@angelatlarge I guess someone pinned it to the top of the list

angelatlarge

@jippie How do you do that?

abdullah kahraman

07:07

Morning!

jippie

@angelatlarge you don't :-p

user61389

@angelatlarge you first need teh powerz

user61389

@abdullahkahraman hello :)

angelatlarge

@CamilStaps I see

jippie

morning @abdullahkahraman

angelatlarge

07:08

@abdullahkahraman Hello, fellow hoi polloi!

abdullah kahraman

@angelatlarge Thanks for teaching me a new term today

angelatlarge

@abdullahkahraman Just doing my job. Language police while @AnindoGhosh isn't around.

abdullah kahraman

Girls don't speak C18 nor SPI, so @CamilStaps can't communicate with them

@jippie Good one lol

angelatlarge

@abdullahkahraman It was 67% power-hungry privileged corrupt punks here. Now it is only 50%.

abdullah kahraman

@angelatlarge So you mean the "room owner" shit?

angelatlarge

07:12

@abdullahkahraman Yes.

Anindo Ghosh

@angelatlarge I'm around. I'm back home.

angelatlarge

@abdullahkahraman They are the owners. They have the means of production. We are the poor, huddled masses, yearning to be free.

@abdullahkahraman And now it is back up to 60% again.

abdullah kahraman

@angelatlarge If you want, I can slap ~~both~~ all of them by my powers.

angelatlarge

@AnindoGhosh I submit my badge, colonel

@abdullahkahraman Your powers don't mean much here I am afraid.

@AnindoGhosh You want to take that preposition, or should I?

abdullah kahraman

@angelatlarge Yeah, I have to travel a lot

Anindo Ghosh

07:14

@angelatlarge Continue the language policing :-)

user61389

I don't like this mutiny talk, perhaps I should restrict access to the room.

abdullah kahraman

This is cool!

►

angelatlarge

@CamilStaps That sounds like fun! "I'll just take my room and go home"

@abdullahkahraman GACK!

abdullah kahraman

@angelatlarge Reminds me Eric Cartman

angelatlarge

@abdullahkahraman You can't post that here

abdullah kahraman

07:15

@angelatlarge Arcs are cool

angelatlarge

The last question had answers by Yolco, Hoppo, and Yurly. Methinks that the end is nigh

That means: time to go to bed.

user61389

@angelatlarge lol, goodnight

angelatlarge

@CamilStaps Have fun, hanging out in your room. By yourself :)

abdullah kahraman

@angelatlarge Bye

user61389

09:25

What about links like in electronics.stackexchange.com/a/68719/17592? Promotional, but relevant. To edit or not to edit?

Anindo Ghosh

09:45

@CamilStaps Are you referring to the first answer by Mr Hedgehog (which has +7 votes), or the second one? The second one is essentially link-only and needs to be improved IMO.

user61389

@AnindoGhosh no, the answer of DIY PCB. Is that your second one?

Anindo Ghosh

@CamilStaps I flagged that DIY PCB one for deletion.

user61389

@AnindoGhosh okay, thanks

jippie

m

@AnindoGhosh why?

it doesn't look commercial, it has an on topic blog post

user61389

@jippie still link-only

Anindo Ghosh

09:56

@jippie Link-only answer, in effect - and a bare promotion of the poster's web site, without even prettying it up with some explanatory text that would add long term value, especially when that link dies some day.

jippie

fair enough, but I would give him a chance to extend the answer after @CamilStaps's comment

@AnindoGhosh about dead links, how about all the datasheets that we link to?

Anindo Ghosh

@jippie As long as the constituent text is meaningful, and the post isn't just a datasheet link, the value add is created. After all, so long as the part number is specified, another datasheet can certainly be located if the one linked to, link-rots and dies.

@jippie I would still flag a link-only answer for deletion, if the post were just the datasheet reference.

jippie

m

user61389

@jippie those comments are automatically added when you review a Low Q post I believe

jippie

m

Anindo Ghosh

10:12

Hey, since two bright sparks, @jippie and @CamilStaps are both online, would either of you care to suggest some options I have for a very minimal-tech/low-tech solution to the following requirement? I have a piezo bender (piezo speaker), that is exposed to ultrasonic as well as possibly sonic vibration. I need to harvest the power transduced by the piezo, specifically due to the vibrations in the ultrasonic range, in order to flash an LED.

No specific flash cycle needed - The LED should just flash when enough charge is built up in a capacitor.

user61389

@AnindoGhosh sorry, not my cup of tea

Anindo Ghosh

@CamilStaps Not your Glass of Google either? ;-)

jippie

@CamilStaps @AnindoGhosh make the boy a glass warm milk

user61389

@AnindoGhosh I can try, but then I'll first figure out what you're talking about ;) (Piezo bender, power transduced, never heard of that, going to search)

jippie

@AnindoGhosh Can you actually measure the output of the piezo?

Anindo Ghosh

10:16

OK let me break this into two parts: The band-pass filtering can be a passive RC + CR, I guess. Then I could do a simple diode bridge, perhaps Germanim diodes, to rectify the signal, since the voltage across the piezo is a couple of volts.

@jippie Yes, I'm getting 1.0 to 3.2 Volts peak to peak across the piezo when exposed to the ultrasonic signal.

user61389

@AnindoGhosh ok, I understand you now, I think. Can't you just amplify the signal?

Anindo Ghosh

@CamilStaps This has to be an unpowered device, i.e. power coming solely from harvesting the piezo's signal.

user61389

@AnindoGhosh ah I see, and you don't have enough power, so you want to store it and let the LED blink?

Anindo Ghosh

@CamilStaps The whole device would go into a hotglued tiny ABS plastic case, with the LED visible from outside, the device then gets thrown into the water (many of them), and if they receive an ultrasonic vibration, they flash occasionally. This is monitored by a camera that just records the flashes over an extended exposure.

@CamilStaps So, no battery in the device, and it will have to be low cost, since these are essentially throwaway devices.

user61389

@AnindoGhosh whoa, cool. Sure you aren't James Bond's Q?

Anindo Ghosh

10:22

@CamilStaps I wish :-D

user61389

But would storing the charge in a cap and release it when enough work? Those static electricity generators work something like that, don't they? Would that be possible on smaller scale?

Anindo Ghosh

@CamilStaps It should work, but how, is the question.

@CamilStaps @jippie I've found this so far. intechopen.com/books/small-scale-energy-harvesting/…

user61389

Do you have 4000$ for this project?

jippie

@CamilStaps No he isn't because Q wouldn't as us for ideas.

user61389

@jippie perhaps they're recruiting :o

Anindo Ghosh

10:35

@CamilStaps If you delete 3 zeros, we'd have a good per-unit price for a prototype ;-)

@CamilStaps I'm looking for low-tech, not loaded-tech ;-)

user61389

@AnindoGhosh then I'll search some more :)

Anindo Ghosh

@CamilStaps Thanks :-)

So let's leave the filter aside for now. Rectification with a germanium diode bridge seems plausible. That leaves the charge-discharge circuit concept.

user61389

@AnindoGhosh How much current can you draw from the piezo?

Anindo Ghosh

@CamilStaps basically the peizo works out as a voltage source with internal impedance of about 500 to 1k Ohms (depending on frequency of source vibrations)

user61389

Ehm.. Would it be possible to drive a very XLP uC on the piezo constantly to time the charge / discharge periods?

jippie

10:43

@AnindoGhosh you probably need something to trigger when a capacitor reaches a certain level. Like a diac, but for 3V instead of 30V

@AnindoGhosh Do they still sell germanium diodes in India? Why not a low capacity Schottkey?

Anindo Ghosh

@jippie A low voltage diac like device would be perfect.

jippie

@AnindoGhosh of course it would, that's why I was typing that.

Anindo Ghosh

@jippie I can get GE as well as Schottky small-signal diodes easily. The Ge ones are cheaper but that's not a deal-breaker.

jippie

Ge has probably higher resistance

tvs?

What is the difference between e TVS-diode and a Zener?

Anindo Ghosh

@jippie The way I understand it, the TVS can deal with higher impulse currents, but has a less sharp knee of the graph.

jippie

10:54

Too bad, I thought a TVS would break down like a diac does, but it is apparently more like a Zener optimized for another goal

@AnindoGhosh if you can get the voltage up to about 70V, you could use a neon lamp.

Anindo Ghosh

@jippie That would mean a transformer - and one doesn't want a transformer in a throwaway underwater device :-)

jippie

@AnindoGhosh nl.mouser.com/new/littelfuse/littelfusesidacbaseband

Anindo Ghosh

@jippie Voltage too high.

Hmm how about if I use an N-mosfet with the gate tied to the Drain?

Won't work, no hysteresis.

jippie

@AnindoGhosh Greinacher cell

Anindo Ghosh

Hysteresis. I wonder if there's a 555 based option.

jippie

11:08

@AnindoGhosh sure it has a hysteresis'like effect.

If a voltage exceeding the switching voltage (VS) occurs, the SIDACtor devices crowbar and simulate a short circuit condition until the current ﬂowing through the device is either interrupted or drops below the SIDACtor device's holding current (IH). When this occurs, SIDACtor devices reset and return to their high off-state impedance.

@AnindoGhosh you'll have to start by measuring how much power (volt and current) you can get from the piezo.

Anindo Ghosh

@jippie I'm getting a steady 4 mA at 2 Volts, that's the optimum power point I've found so far.

jippie

When in the water and activated with US?

Anindo Ghosh

@jippie That's 8 mW. Not enough for the LEDs in question to be visible through water.

I need closer to 40 mW for 0.1 second, and gap time can be any amount, even several seconds or a minute.

@jippie Yes, with the US source very close to the piezo. Realistically the source will be a bit further, so I should plan for perhaps 1 mW from the piezo.

jippie

can't you attach the LED to the power switch of the US source if it is so close? :-p

I'm no longer answering questions until I reach 8850 rep or more.

Did you see this @AnindoGhosh

timesofindia.indiatimes.com/tech/tech-news/internet/…

Anindo Ghosh

@jippie No, the US source is an algae cleaning device, self-propelled, that floats around the pond or water body. These devices are supposed to enable tracking of the coverage the ultrasonic source has over time.

@jippie Yes, I did. I've always assumed there are organizations tracking my comms anyway - not just within the country, but across the internet.

@jippie Hmm, a Greinacher circuit using schottky diodes seems worth exploring.

which is causing some alert signal to be triggered in my brain. Isn't there some energy harvesting IC from TI that already does something like this? Let me check.

jippie

11:33

@AnindoGhosh yes, I was wondering why you were ignoring those

Anindo Ghosh

The energy harvesting seems to be a non-critical problem. There are single-chip-and-capacitor solutions from Linear Tech.

@jippie Because I am sleep deprived, have not slept more than a couple of hours a day for 4 days, so brain is not fully working.

jippie

@AnindoGhosh well maybe you should do something about that then.

Anindo Ghosh

@jippie So I'm back to the key problem - triggering when sufficient charge collected, and letting it drain to a low charge, just like a diac does.

AshRj

Anybody uses PSpice here?

jippie

go out, buy a bottle of whiskey, pour yourself a glass ...

Anindo Ghosh

11:35

@jippie You're right. I think I'll take a nap for a few hours. Thanks for pointing out the obvious which my brain wasn't picking up. Bye now, back in a few hours! Thanks Jippie.

jippie

@AshRj did that in '93 or so

@AnindoGhosh :)

AshRj

@jippie I was born then :P

Cant find the library for a IC

Any idea where do I look ? Google ain't helping

jippie

@AshRj manufacturer?

Anindo Ghosh

►

@jippie They've done a bigger version of my piezo harvester in Holland, at a nightclub.

AshRj

@jippie Of what ?

jippie

11:41

@AshRj the ic?

AshRj

@jippie Just know the number 7447. So, I need to look at the manufacturer site ? Do they usually provide libraries for simulation software ?

jippie

that is a TTL standard logic thingy. If it exists it shouldn't be too hard to find. in '93 very few digital logic IC's were available as library for PSpice. The circuit is relatively complex (requiring long calculation times) and all you want to do is simple digital boolean algebra.

@AshRj You don't ~~need~~ want to use nodal analysis to solve boolean algebra

to answer your manufacturer question, you can of course upload an image of the IC.

BTW: most 74xx IC's today are 74HC(T)xx or 74LSxx

HC(T) is High speed CMOS (with TTL levels)

LS is Low power Schottkey

it refers to the technology how the chips are made. The old 74xx chips are pretty power hungry, can usually drive only limited current and have a non-neglectible input current.

AshRj

@jippie Thanks. I found 7446A which seems to do the same thing as 7447. Not really concerned about power at the moment.

jippie

It's been ages since I used terminology like fan-in and fan-out ... typical TTL

I guess you want to simulate the same chip / techonogy as your circuit will have.

anyways, I've been typing enough for a while

/me is out

tigrou

13:23

Hi everybody. I'm running a led matrix message scroller under ISIS but have an issue : If i run the circuit step by step everything works ok (leds are turned on/off row by row to form a character as excepted); however if i run simulation full speed, only garbage is displayed. Circuit has been tested in real life (by someone else) and works ok. I think the main reason is ISIS turning leds on /off immediately while in reality it took some time (persistance of vision).

PeterJ

@CamilStaps, with that crappy long looking Google link you edited do you know what all the extra query parameters are about? I wondered if it was some sort of paid referral thing but couldn't work it out.

tigrou

I have tried to play with "animation options" under isis. increasing FPS to 50 reduce the problem (less garbage is shown mostly "ok" characters. but it is still not ok. Can somebody help me ?

user61389

@PeterJ no idea, but google adds a lot parameters. You should never copy-paste a google link, it includes all kinds of useless information like browser, ...

PeterJ

@CamilStaps, I was wondering how someone could do it by 'accident' - but see now what you mean they must have found a link they found useful and then copied the link from the main search page.

user61389

@PeterJ yep, google uses links to its own website instead of to the page itself to log your behaviour. You normally don't see it, you're being redirected.

PeterJ

13:28

@tigrou, I've never used ISIS but guess apart from POV you've mentioned some simulation products send messages to a seperate GUI thread to update the display, so the delay caused by that may come into play as well.

abdullah kahraman

13:39

@tigrou You cannot expect it to work as-is. It is simulation and the speed of it depends on how fast your computer is.

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