Electrical Engineering

11:00 AM

@Hakonbogen OK, now the optotransistor part. It'll have some typical collector current of say 1 mA when on, perhaps a fraction of a microamp when off. Which means, if you want a voltage output from it, you set it up like a transistor switch. put current limiting on it, ans you're done. (you can look up suitable circuits for current to voltage using BJTs on your favorite search engine). Broadly, for a 5 Volt supply to be limited to 1 mA, you need 5 kOhm resistance in series. ...

So, connect the collector to 5 Volts, the emitter to a 5 K resistor and thence to Ground. The Emitter pin will then be at zero volts when no reflected IR exists, and will be at around 4.x, nearly 5 Volts when lots of IR falls upon the sensor part.

Hakonbogen

Oh

Anindo Ghosh

If you think you're not getting enough voltage out of this arrangement, reduce the resistor to perhaps 2.2 kOhms.

Hakonbogen

Yes

So just read when the arduino gets 4 volt back

Anindo Ghosh

@Hakonbogen Actually you have two choices - Either analogRead(), or you can use pin change interrupts on a suitable digital pin, since the 'duino will read the near-5 Volts as a high digital signal. Google all those terms and you'll find enough answers.

Hakonbogen

Will try

Anindo Ghosh

11:07 AM

@Hakonbogen Also, for the switching, you have another choice as well: Put a 5k resistor between 5 Volts and the Collector, connect your sensing pin to the collector as well, and connect the emitter to Ground. That way, when there is an object nearby, the signal will go low, and when there isn't, the signal will go high. Opposite logic to putting the resistor on the emitter side.

Found you this: arduinotronics.blogspot.in/2012/06/…

Hakonbogen

Thanks

Anindo Ghosh

The TCRT5000 is one of the most popular reflected-IR proximity sensors for hobbyists, so lots of examples, blogs, schematics etc out there. However, what I typed here is a walk-through from first principles, so it'll work even if you some day use another similar component. Hope that helps you be a little more clear on what goes where, why and when. :-)

Hakonbogen

Can't wait to get the part and start

Yes it really does!

Thanks

Anindo Ghosh

Anything else? And yeah, please feel free to capture this discussion and paraphrase it if you want to make it an answer to your own question: That is a practice accepted on this site.

Hakonbogen

I will need to try it out before answering

i'll have to read some more on that site, may have more questions after reading

:-)

Anindo Ghosh

11:14 AM

@Hakonbogen There, Andy has posted an answer for you, perhaps less detailed than the tutorial I just gave you, but perfectly valid. :-)

@CamilStaps The atMEGA328 pretty much fits your requirements. It comes in both DIP and SMD, supports variable voltage supply including 3.3 and 5 Volts, and is also well supported by existing code out there simply because it's one of the best-known MCUs to the 'duino hobbyist community. Later, you can switch to more tightly spec'ed AVRs like the ATTiny series, to save cost, depending on specific project requirements.

user61389

@AnindoGhosh thanks! (no picky comment on PIC vs AVR? :)) Perhaps you want to make it an answer?

Anindo Ghosh

@Hakonbogen Please un-star my comments / tutorial, starring is for highlighting messages here for others to see when they get into chat. My messages were of interest primarily to you, so they don't need to be starred.

@CamilStaps I'm avoiding getting into writing answers, because I just get too engrossed in trying to make my answers definitive, which I can't afford right now. And no, an MCU is an MCU is an MCU. If I had to compare, I'd say I personally like the MSP430 family for being 16-bit MCUs at 8-bit prices, but they killed the hobbyist market with the launchpad price hike.

@CamilStaps Also, the MSP430 doesn't do 5 Volts IIRC, which to my mind is a serious lacuna for the hobbyist market.

user61389

@AnindoGhosh okay then! Thanks anyway of course :)

Anindo Ghosh

@Hakonbogen Also, you can always come back and review any part of the chat transcript, even months later: The chat transcripts are searchable, and you can also bookmark any particular message so you can find the thread of messages later.

user61389

@AnindoGhosh in a recent project I had to make an extra 3.3V supply because I had to use the MSP430, so it indeed does not support 5V

Anindo Ghosh

11:28 AM

@CamilStaps Yeah, that sucks because hobbyists generally have a 5 Volt USB charger handy.

user61389

@AnindoGhosh very true

user61389

@AnindoGhosh quick question, can't find it (not used to the Atmel website) - I can choose between 328-PU, 328P-PN and 328P-PU. Do you know of any significant difference?

user61389

PU/PN is probably temperature, isn't it? But what's the P?

PeterJ

@CamilStaps, here's a table, the P is PDIP for the DIP parts:

atmel.com/devices/atmega328p.aspx

user61389

@PeterJ Cool, thanks! :)

Anindo Ghosh

11:38 AM

First P is picopower, second P is PDIP, not sure what N and U are, maybe RoHS lead-free etc.

user61389

@AnindoGhosh according to the table temperature indeed, N is industrial

Anindo Ghosh

@CamilStaps Fair enough.

Hakonbogen

@AnindoGhosh Didn't know about the starring, sorry. It says its too late to undo

Anindo Ghosh

@Hakonbogen No worries, I'm sure @Kortuk can do it when he gets in. I should have mentioned it earlier.

PeterJ

Stars should be reserved for the most profound comments, is that right?

Anindo Ghosh

12:05 PM

@PeterJ Or perhaps the most amusing. :-)

PeterJ

Funny business has no place in EE as it makes others look unprofessional.

W5VO

1:33 PM

@PeterJ I hope that's sarcasm

PeterJ

@W5VO, yep it sure is :)

@W5VO, is your name a HAM callsign? My dad used to be into it and the W5 prefix looks somewhat familiar. Australia is VK followed by the first postcode digit, for example VK7 where I live.

W5VO

@PeterJ Yes it is. I've heard some Australians on before, but I don't think they could hear me

user61389

@PeterJ really? So you can't see on the callsign who has what license type? Or don't you have different licenses?

W5VO

@CamilStaps In the US, you need certain license classes to hold certain types of callsigns, but you can keep your original call after you upgrade

PeterJ

@CamilStaps, I think in Australia they put an 'N' out the end for for novice but can't remember now.

user61389

1:46 PM

@PeterJ okay :)

Kortuk

2:07 PM

@PeterJ Stars should be reserved for anything you feel like pointing out to others, anything you feel like.

user61389

-2

Q: How to figure out the equation?

Is it possible to figure out the equation of this part of the schematic, just this part? I am having trouble to figure the same out.

user61389

Any idea what this guy means?

PeterJ

@Kortuk, sometimes my dry Aussie sarcasm / humour is missed ;)

Kortuk

@PeterJ I could tell you were sarcastic, but there are many that really do think there are rules for stars.

@PeterJ star whatever you want.

3

W5VO

@Kortuk By that logic, can mods unstar whatever they want? ;)

Kortuk

2:18 PM

@W5VO No, we only abuse powers when no one is looking

4

W5VO

@Kortuk KK, I'll kick everyone from the room and then unstar everything I want to :)

Kortuk

@W5VO DOET

user61389

2:52 PM

-4

Q: How to figure out the equation?

KL30 is actually a 12v supply. But i need to figure out the real time value of the same. So,i take this KL30 input,at Port_A_Pin_1 and using ADC get a digital value as the output. Now to able to reverse engineer the value recieved from ADC,i need the equation so that, i can calculate the real-...

circuit schematics

user61389

He has edited, but what's 'the real time value' of a power supply? Is that a commonly used term? -- never mind, got it :)

PeterJ

3:20 PM

@W5VO, I'm about to head off I think doing that would be an excellent use of your free time!

W5VO

@PeterJ Why thank you :)

David Kessner

4:04 PM

Morning all.

user61389

4:29 PM

@Kortuk @W5VO Bill again

angelatlarge

@CamilStaps Did you see, another answer showed up.

Hallo all

@CamilStaps Kill Bill?

user61389

@angelatlarge hi! What do you mean?

angelatlarge

3

A: Efficient reloading data / pushing data from server to client

This question has been asked a number of times, but in a slightly different ways. Here are a few references that are worth a read: What are Long-Polling, Websockets, Server-Sent Events (SSE) and Comet? Using comet with PHP? Apache with Comet Support Server Scalability - HTML 5 websockets vs Com...

user61389

@angelatlarge oh, there, yeah. It even has 3 upvotes now!

angelatlarge

@CamilStaps It had two before I upvoted it :)

@CamilStaps Seems like a useful answer

user61389

4:37 PM

@angelatlarge nice gesture

angelatlarge

@CamilStaps Well, I think it was good. It wasn't a gesture per se, but thank you

user61389

@angelatlarge or are you after the sportsmanship badge? ;)

angelatlarge

@CamilStaps I don't think my answer will get enough votes for that, and it's probably too late anyway

user61389

@angelatlarge your answer only has to have a positive score, so this upvote does get you closer to that badge

angelatlarge

@CamilStaps Oh, sorry, no Sportsmanship can happen, yes, you are right

user61389

4:39 PM

@angelatlarge of course I am. I'm always right.

angelatlarge

@CamilStaps Forgot about that. Sorry

I see you decided to come over to the dark side.

5

Q: Switching from PIC to AVR

I have worked with PIC16 and PIC18s for over three years now and would like to get to know AVR as well. I have no specific project in mind, but would like to try around with the different architectures. uC's software I am familiar with Assembly and C for PIC16 and PIC18. Do the Assembly and C va...

microcontroller pic avr microchip atmel

user61389

@angelatlarge I liked Olin's comment, but couldn't upvote because he wants to close that question :(

user61389

angelatlarge

@CamilStaps Your new gravatar?

user61389

@angelatlarge :) I recently thought of using a picture of me as 7-year-old playing soccer, but didn't in the end -- I'm out for some time

angelatlarge

4:53 PM

@CamilStaps I like the pic. Maybe it should be a community ad for AVR?

user61389

5:10 PM

@angelatlarge haha! Definitely :)

angelatlarge

5:25 PM

@CamilStaps Do you know of a way of changing the SO shortcut keys? I am annoyed by having to hit Ctrl+L for link, when everything else I use requires Ctrl+K.

user61389

@angelatlarge no, I always just type it in manually :) did you try Meta Stack Overflow?

angelatlarge

@CamilStaps You mean searching on Meta Stack Overflow? I thought it'd be easier to ask you, since you are a veritable repository of such info

@CamilStaps Also, any tips for efficient searching of transcripts?

@CamilStaps I am noting that you have taken to Stack Overflow for C-questions, and are getting them answered. I think that's good.

@CamilStaps You should warn me first though, so that I can get free beer off you :)

@CamilStaps Those C/C++ guys on Stack Overflow have itchy trigger fingers

user61389

@angelatlarge hah, no, sorry, but thanks. Yes, I meant searching. You can use the search bar in the top right for transcripts, but I don't think it has special functions like the on-site advanced search.

user61389

@angelatlarge yeah, but I still don't like the community style. I wanted to warn you, but you weren't here ;)

angelatlarge

@CamilStaps Yeah, for instance, I want to find all messages from @jippie with a link in them :)

@CamilStaps Well, thanks for thinking of me :)

user61389

5:32 PM

@angelatlarge perhaps there's a data dump somewhere

angelatlarge

@CamilStaps I am manually looking through the transcript now...

user61389

@angelatlarge what about this? chat.stackexchange.com/…

angelatlarge

@CamilStaps Cool! How did you get there?

user61389

@angelatlarge with the search bar in the top right! :)

angelatlarge

@CamilStaps Ha! What do I know. Well, thanks, and there is the message I was looking for.

user61389

5:34 PM

@angelatlarge good :)

angelatlarge

@CamilStaps Another question: me and Anindo had a long discussion about my battery question here in chat. I want to put it together as an answer to my own question, and I can't decide whether to post it as CW or not. I can see arguments for both sides. What do you think?

user61389

@angelatlarge you offered him to answer, right? If he wants to answer it later on, you can wait a few days. If he doesn't want to (which is the case IIRC), you can add it yourself and I wouldn't post it as CW. You're putting effort in summarizing the data and only therefore you can get the reputation if it's up to me. You can of course also ask Anindo if he'd be okay with that.

user61389

Just in time :)

angelatlarge

"So I'll keep this very brief"

user61389

@angelatlarge isn't that correct English? Or what do you mean?

angelatlarge

5:39 PM

@CamilStaps I don't think you did keep it very brief :)

user61389

@angelatlarge it's a short answer for such a question :P

angelatlarge

@CamilStaps Sure. I think we can agree that your answer was brief in a relative sense.

user61389

@angelatlarge but what about your CW question?

angelatlarge

Who the hell is starring all the EE garbage on the right?

Anindo Ghosh

@angelatlarge Hi, sorry, was away. Yes, I am more than happy to have you summarize / extrapolate and write up an answer. No, I don't think it should be community wiki, because it does take effort. Most important, OCD me would be very antsy if the answer didn't get written, and I really can't do answers till I get these 2 protos and the board from yesterday done.

angelatlarge

5:42 PM

@CamilStaps It will not be brief. Anindo wants me to make it into an answer: he is too concerned about his MOSFET switch right now to answer questions

It's a miracle! He is alive!

user61389

@angelatlarge some newbie. I must say the hover-message on the star can be somewhat confusing.

jippie

@angelatlarge who in his (m/f) right mind would want to find all my messages (with or without link)

good morning @all

angelatlarge

@jippie Hi @jippie. I was looking for the HV fuse-setter link again.

...and I found it.

user61389

@jippie morning

Anindo Ghosh

@CamilStaps Just gave you a very long-lasting LED indicator solution.

user61389

5:50 PM

@AnindoGhosh but I didn't want the blinky stuff! But I'll test one of my LEDs for the current.

Anindo Ghosh

@CamilStaps Even without blinky stuff, I have LEDs at my desk which are quite visible in a normally lit room at 1 mA

jippie

blinky stuff?

user61389

@AnindoGhosh yeah but "After that, if you could let it blink, say once a second for a tenth of a second, at perhaps twice said minimum current, you'll get insane longevity." doesn't seem relevant to me, does it?

Anindo Ghosh

@CamilStaps and the reason I'm not posting an answer is, I'll be tempted to see how low a current I can get the LED to light up with.

user61389

0

Q: Energy-efficient LED driver circuit

I want to light a normal LED (2.5V, 16mA) for as long as possible on two AA or AAA batteries. It does not have to blink or so, just stay on. The LED doesn't have to light at the max, as long as it's visible from ~1 meter. I might not be looking for the fewest power consuming circuit, as some oth...

led batteries light efficiency

Anindo Ghosh

5:52 PM

@CamilStaps I added longevity options: It's called "bonus" :-)

@CamilStaps OK, 0.3 mA and still visible: This is a green SMD LED. Incidentally, green LEDs are the most visible to the human eye: I'd posted an answer a long time ago with spectral charts mapping human vision etc.

angelatlarge

@AnindoGhosh is right that to get the most longevity you'll want to PWM your LED. AFAIK you get more brightness out of a led per unit of energy by pulsing it at some low duty cycle (10%) at higher current than by running a lower current 100% of the time. This is due to the human persistence of vision effect.

jippie

@AnindoGhosh but will it be visible for the longest time?

angelatlarge

@CamilStaps I am willing to write that up as a very crappy answer ;)

user61389

@AnindoGhosh okay then :) pity! You don't want to answer anything anymore, do you? ;)

user61389

@AnindoGhosh nice! But I beat you: 1.9V/0.25mA :)

Anindo Ghosh

5:56 PM

@jippie That question left me totally blank.

jippie

if a green led is visible for 5 minutes at a single charge, but a red led (taking more current) lives for 15 minutes on a single charge

user61389

Oh and can some 10k user (Anindo? :D) / mod clean up the comments on that question?

jippie

for example

Anindo Ghosh

@angelatlarge The increased visual impact thing is apparently only be true for blink frequencies in single digits - and you can then actually go down to well under 10% duty cycle, as long as individual on-pulses are greater than 1/20th or a second or so (I'd actually found out the limit, but I can't recall now).

angelatlarge

@AnindoGhosh THe limit is written up in wikipedia and actually varies from person to person. I think 20 timers per second is about right.

Anindo Ghosh

6:01 PM

@jippie Ahhh I get it now. OK, here's the thing: This is based on a few LEDs I have on hand. I can see the red lit all the way down to 0.5 mA. The green I can see down to 0.3 mA. Their voltages are 1.7 and 1.9 Volts each.

@angelatlarge Yes, I never trust WikiPedia on LED questions, since it's a favorite area of study for me. I had determined experimentally what minimum pulse duration I need for a green LED to be visible better than if it were always-on.

angelatlarge

@AnindoGhosh This was not about LEDs per se

Anindo Ghosh

@jippie Now, the Vf of the LEDs becomes irrelevant for dissipation calculation, if you are using resistors for current limiting. I'm sure you know why.

@angelatlarge Blinking stuff = LED. I have a simple understanding about life.

Ahh damn, my curiosity is killing me: Does anyone know why the forward voltage of the diodes is irrelevant for calculating power dissipation, like I said?

It used to be a fun question I asked in workshops and stuff.

user61389

@angelatlarge flag it! Flag it!

The Photon

@AnindoGhosh Yes we know.

angelatlarge

@AnindoGhosh I think @ThePhoton knows.

user61389

6:14 PM

@AnindoGhosh I think @angelatlarge knows who knows.

Anindo Ghosh

@ThePhoton Damn, of course you would know. I hadn't realized you were reading chat :-)

jippie

@AnindoGhosh You two are saying P != U × I? and @ThePhoton

The Photon

P = V * I (in American)

Anindo Ghosh

@jippie I was very specific about what I said: Camil wants maximum run-time for his LED, I said that the forward voltage of the LEDs is irrelevant to such computation. :-D

jippie

OK guys, I gave you all day to think about this: I need a cat-on-my-desk-(where-I-work-with-sensitive-electronics)-detector that I can connect to a microcontroller. Also I need a scare-cat-from-desk-actuator that can be controlled by a microcontroller. Ideas anyone?

The Photon

6:20 PM

@jippie Fire sprinklers

Anindo Ghosh

@jippie Ultrasonic random-sweeps, in the low ultrasonic range. Add a PIR to it if you want to conserve power.

jippie

the pir will respond to myself too

US will too

:-/

Anindo Ghosh

@jippie This is true, but if you are present, you can bloody well scare off your own cat!

The Photon

@jippie Keep the door to the room closed?

jippie

I don't want to be scared away myself

@AnindoGhosh I can be a bit absent minded when it comes to that

Anindo Ghosh

6:22 PM

@jippie The human male is way less sensitive to ultrasonic vibrations than the human female.

The Photon

@jippie Place a cat-attractant (like a CRT monitor or a warm pillow) in a different room?

Admittedly, my answers are all "big-picture" kind of solutions...

Anindo Ghosh

Hang a ball on a long string just barely within kitty's reach somewhere a bit away from your desk.

jippie

@AnindoGhosh I don't want my cats to be scared of me, I just don't want them on my desk

Anindo Ghosh

@ThePhoton That would need a big CRT, my CRTs just show small pictures.

jippie

@AnindoGhosh that works for about 5 minutes

Anindo Ghosh

6:24 PM

@jippie Yes, because after that you'll probably be distracted by that pendulum yourself, and go play with it ;-)

jippie

come on @guys quit it with the low tech solutions, we are in an engineering chat.

...

user61389

@jippie with respect, you wanted to use arduino! ;)

jippie

@CamilStaps I changed my mind to using CATtiny

Anindo Ghosh

@jippie Ultrasonic output isn't technical enough for you?

jippie

(or a catduino at best)

user61389

6:28 PM

@jippie yeah, I starred that :P but it got overshadowed by the pointless stars

jippie

@AnindoGhosh I appreciate the cats hanging around, just not on the desk. US will scare them away from the room (and its vicinity)

Anindo Ghosh

@jippie Not so. Point the transducer upward and fit it under the table.

jippie

will an el cheapo range detector do?

Anindo Ghosh

@jippie If you want to go el cheapo, just get a kevlar-cone or plastic-cone ultratweeter, or else a half dozen piezo benders.

@jippie range detector, no, way too little power and I'm not sure it will do frequency sweep well.

@jippie Ideally at least 10 watts RMS. Added benefit: Dust and speckles will not settle on your desk as much.

jippie

I have the range detector lying around

Anindo Ghosh

6:33 PM

@jippie I have this and it does well up to around 35 KHz.

jippie

that is why I asked.

Does this link show correctly for you:

translate.google.com/…

Anindo Ghosh

Researchers from the U.S. Defense Advanced Research Projects Agency (DARPA) have developed the first integrated circuit strengthen shows at a frequency of 0.85 THz. This is an important step towards the goal to develop. Integrated circuits for a frequency of 1.03 THz With these circuits, advanced communication and sensor systems are realized as Visar radar system (Video Synthetic Aperture Radar) that works just as effectively under cloudy weather as infrared sensors in clear weather for military purposes.

jippie

@CamilStaps how can I include a link in a comment and change the text on it?

user61389

@jippie [text](url)

2

user61389

And I'm out for a little while

angelatlarge

6:38 PM

Done

0

A: Rechargeable battery type recommendations for a 1-2 amp bicycle LED circuit

(This answer summarizes Anindo Ghosh's suggestions on the topic made in EE chat plus a few of my own observations. Please note that I am not considering this answer definitive: just want to add something else to the mix of suggestions) This answer assumes (without justification) a LiPO battery-b...

The Photon

@jippie Is it supposed to come up in Dutch?

jippie

no the original article is in dutch

The Photon

schakelingen is amplifier?

jippie

but when I throw it in google translate, I get ... weird results (to say the least).

The Photon

or transistor?

Anindo Ghosh

6:44 PM

@angelatlarge "red and blue channels can be as much as 3.4" - No, red is the easy one, it'll be 1.7 to 2 volts. Blue is the high one at 2.8 to 3.6 Volts. Green is midway.

jippie

circuit

angelatlarge

@AnindoGhosh Typo

jippie

@ThePhoton geintegreerde schakeling = integrated circuit

first ic that shows amplification for f=0.85THz

Anindo Ghosh

4

A: Using a TLC5940 to control LEDs with different forward voltages

The TLC5940 requires a minimum headroom (anode voltage applied to LED) of about 0.7 Volts greater than the LED's Vfwd for driving 60 mA, and 1.2 Volts for 120 mA. If the headroom is lower than this, the channel is detected as an open LED. Actually, "open" is detected at 0.4 Volts or lower headro...

The Photon

@jippie Got it. I can 90% read it.

jippie

6:46 PM

@ThePhoton it is amazing, near 1THz, isn't it?

Anindo Ghosh

@angelatlarge e2e.ti.com/support/power_management/led_driverslcd_bias/f/192/t/…

Oh, and @Angela you can upvote that answer of mine any time you like :-)

@angelatlarge Wasn't LiFePo4 my starting suggestion? :-)

jippie

when I was in looniversity, I was taught that everything below 1GHz was DC :o)

user61389

That Joule thief consumes 48mA, that isn't good, right?

jippie

Imagine in a couple years they might say that about everything < couple 100 GHz :)

@CamilStaps depends on its output, doesn't it?

user61389

By the way @jippie I found the solution for your problem:

user61389

6:51 PM

user61389

@jippie it's a normal LED, 16mA normally but still lights up at 0.25mA

Anindo Ghosh

@angela Also, instead of a TLC5940, if you use an AS1119, that comes with ain integrated charge pump for 144 LEDs, hence less worry about voltage.

3

A: Best way to control 130 - 140 LEDS with Arduino Uno 32/64 bit led drivers?

There is actually at least one 132-LED driver IC, the AS1130 132 LED driver with PWM ($2.99). This precisely matches your application requirement at least on the LED count. AMS has a versatile set of LED drivers: For instance their 144 LED driver (AS1119) with its integrated charge pump for dri...

jippie

@CamilStaps so your joule thief has about 0.5% efficiency?

user61389

@jippie I'll go ask on criminals.se for tips

2

Anindo Ghosh

@CamilStaps There you go: Save power by ultra-low current driving. Simple!

user61389

6:54 PM

@AnindoGhosh yeah but I can't easily adjust the voltage as I'm on batteries

Anindo Ghosh

@CamilStaps Keep the voltage whatever it is, at 0.25 mA, that'll still be a ridiculously small amount of power.

The Photon

@jippie Looks like an answer for the "what's the fastest oscillator" question.

user61389

@AnindoGhosh but.. on 2.5V the current isn't 0.25mA

Anindo Ghosh

@CamilStaps 2.5 V, 0.25 mA, Total power is 0.625 milliWatt - just use a resistor to get the current down, that 0.625 mW is inclusive of resistor dissipation.

The Photon

@jippie, here's a link in English:

connect.innovateuk.org/web/espktn/articles/-/blogs/…

Looks like the Dutch was a direct translation of the same press release.

user61389

6:57 PM

@AnindoGhosh yeah okay, but that wouldn't work with lower voltages and the Joule thief is designed for that, isn't it?

Anindo Ghosh

@CamilStaps LEDs are never controlled by voltage, just by current. Unless you want to use a charge pump circuit with current mirror and feedback.

user61389

@AnindoGhosh actually, that was Andy's suggestion

Anindo Ghosh

@CamilStaps The joule thief is not going to help you - simulate it and you'll see. Also, is your voltage 2.5 or is it lower?

user61389

@AnindoGhosh I'm going to use two 1.5V batteries, but their voltage will decrease over time of course

user61389

But still, I must have done something wrong with the joule thief, it shouldn't draw 50mA.

Anindo Ghosh

7:01 PM

at 0.625 mW, do you realize that a single CR2032 3 Volt coin cell will last you 384 hours?

user61389

@AnindoGhosh did you include the decreasing voltage in your calculations?

Anindo Ghosh

@CamilStaps That estimate is based on the CR2032 dropping all the way down to 2 Volts, still sufficient for lighting a green LED.

user61389

Ah yes you did.

Anindo Ghosh

@CamilStaps LEDs, and batteries... my favorite fun topics :-)

The Photon

@jippie, here's another one, actually an oscillator:

ntt-review.jp/archive/…

user61389

7:03 PM

Heh, and what about an alkaline AA/AAA battery? I'm making this for my neighbours and don't want them to have to change a coin battery, it isn't that common here

jippie

@ThePhoton How do they measure > 1THz ?

The Photon

@jippie Mix down.

jippie

@ThePhoton not sure if that makes sense.

Anindo Ghosh

@CamilStaps With a pair of Energizer E91 alkalines, you will get over 6000 mAH at 0.25 mA, which means at least 400 days of operation. In reality the mAh capacity over 3000 per cell will be countered by environmental and leakage factors, bringing the actual value to around the 3k mAh range.

jippie

@ThePhoton sure it does, but you still need a 1.5 THz preamp, wouldn't you?

Anindo Ghosh

7:07 PM

that's per AA cell, so 2 in series = 6 Ah.

user61389

@AnindoGhosh that's still pretty much :) I'll first try to get the thief to work, after that I'll just do it the easy way

The Photon

@jippie You might do it with something more optics-like than electronics-like.

Anindo Ghosh

@CamilStaps Also a good alkaline lasts a decade without significant deterioration.

The Photon

Like combine the beams in a nonlinear optical medium.

Also, lots of averaging.

Anindo Ghosh

@CamilStaps I'm betting the joule thief gives you a month, tops. The two AAs and resistor, over a year easily.

user61389

7:09 PM

@AnindoGhosh huh? That I don't understand. I can see the thief isn't 100% optimal, but it works for lower voltages as well

Anindo Ghosh

@CamilStaps Yes, but current draw increases as voltage drops, so the actual battery capacity sees a sharp drop-off as voltage drops.

user61389

@AnindoGhosh ah so, I see. Okay then, I'll drop the thief, thanks!

Anindo Ghosh

@CamilStaps To transform energy, you need to count the source energy plus the efficiency losses. As voltage drops, efficiency drops, plus source current needs to rise to deliver the same power. Correct?

user61389

@AnindoGhosh if you say so ;) no, I understand! Clear explanation.

Kortuk

@ThePhoton Both. (@jippie). THz has the advantage microwave techniques and optical techniques both work.

Anindo Ghosh

7:12 PM

@CamilStaps Glad I could help. If I were you, I would compute a resistor for not 0.25 mA, but 0.4 mA or so. A bit brighter, still nearly a year on one pair of batteries.

user61389

@AnindoGhosh compute? I was thinking of experimenting, you can't really calculate that resistor, can you?

Anindo Ghosh

@CamilStaps Actually, 0.25 mA to 0.4 mA should give over a doubling of intensity if I'm not mistaken. The LED luminosity is non-linear, rising a lot at the low currents.

@CamilStaps What's your nominal Vf?

Kortuk

@jippie My wife uses a high voltage silicon switch. The switch is an insulator and they hit it with a ps TW laser and cause a very fast conduction between sides and get broadband THz out of it, causing narrowband is much easier.

user61389

@AnindoGhosh what's Vf?

Anindo Ghosh

@CamilStaps Are you going with an old style green LED as I suggested? Then voltage would be say 1.9 Volts to 2 Volts. Use 2.2 or 2.7 kOhms and you are all set.

@CamilStaps Forward voltage of the LED for nominal current (usually calculated at 20 mA)

@CamilStaps The actual figure you need for LED forward voltage, is from its V to I graph, for an I of under 0.5 mA. That value should be well under 1.5 Volts.

@CamilStaps And if I'm correct, then use a 3.3k resistor.

user61389

7:18 PM

@AnindoGhosh no, the box in which it will be put is red, so they want a red one :) Vf=2.2V. I don't have the graph, but I can measure the V for I=0.5mA, wait a moment...

angelatlarge

@AnindoGhosh I linked to that, didn't I?

The Photon

This guy is starting to get on my nerves:

Update 3 @mods I would suggest removing the answers/commenst so far. Incompetence should not be valued, even though it is hard or "unrealistic" to some extent -- it is interesting puzzle that could speed up development when solved or partially solved. — hhh 6 mins ago

Anindo Ghosh

@angelatlarge You did? I didn't click any of the links, so sorry.

angelatlarge

@AnindoGhosh The SMD I was looking at are advertized as 3.4 for B and G

user61389

@AnindoGhosh it's 1.86V. Now how do I calculate the resistor? Simple V=IR, right?

Anindo Ghosh

7:19 PM

@angelatlarge OK, those are the new "ultra bright" type greens. I prefer the classic green LEDs.

angelatlarge

@AnindoGhosh Dollar code

Anindo Ghosh

@CamilStaps Yes, take supply voltage at 3 Volts - it'll drop over time, but so will the current correspondingly. And take current as 0.4 mA

user61389

@ThePhoton he's like me, before, pretty annoying indeed

user61389

@AnindoGhosh thanks a lot! I guess I cannot seduce you to answer?

The Photon

@CamilStaps I don't think you ever called anyone incompetent because they answered what you wrote instead of what you were thinking.

Anindo Ghosh

7:23 PM

@CamilStaps Hmm, let me consider it a moment.

user61389

@ThePhoton no, but I have done other things wrong, but thanks :)

user61389

@AnindoGhosh please do!

angelatlarge

@AnindoGhosh I don't see the relevance.

@AnindoGhosh BTW, where did you get the " 0.7 Volts greater than the LED's Vfwd for driving 60 mA, and 1.2 Volts for 120 mA" - I did not see that in the datasheet.

@ThePhoton +1

Anindo Ghosh

@angelatlarge Oh, I was providing you background info on the actual headroom needed by the TLC part, since I had forgotten the exact numbers the previous time we discussed it. I had estimated 2 Volts, while it is 0.7 for up to 60 mA, and 1.2 Volts above that.

@angelatlarge V(LED) LED open detection threshold 0.4 Volts, and the threshold calculations are somewhere there as well, I can look for them if you need.

angelatlarge

@AnindoGhosh Figure 5 of the datasheet!

Anindo Ghosh

7:31 PM

@angelatlarge There you go :-)

user61389

@AnindoGhosh I used 2.4K, it consumes 0.25mA at 2.5V, 0.42mA at 3.0V - awesome!

Anindo Ghosh

@angelatlarge Now you know why I prefer not to get into posting answers when I'm not all there: I have a habit of getting really involved, I pull out obscure details from datasheets, and stuff.

angelatlarge

Which is titled "Output current vs. Output Voltage. I don't see how we are supposed to realize that this is headroom, without Chris Glaser, TI employee telling us.

Anindo Ghosh

@angelatlarge :-)

OK gtg, later all!

user61389

@AnindoGhosh bye!

jippie

7:33 PM

@Kortuk but does she cook good too?

angelatlarge

@AnindoGhosh I am serious

@AnindoGhosh bye

I suspect that the downvotes on the questions are meant to be downvotes on the OP now.

I am talking about this

-4

Q: Any research to turn Schematics as a picture into a simulation?

Suppose I have a schematics such as the below. I want to fast simulate it: see how the current flow and put my mouse to different positions to see how things work. Since there are many different ways to do the schematics, this requires to break the problem into human-solvable parts and computer-s...

software research feature-extraction

Kortuk

@jippie I love my wife ~~and~~ for her cooking.

@AnindoGhosh Later!

angelatlarge

@AnindoGhosh It was but that was separate from the circuit topology, which I took to be the main contents of your suggestion.

Kortuk

@angelatlarge that seems like an off-topic question.

angelatlarge

@Kortuk Is that a comment on my comment or on the original question?

Kortuk

7:46 PM

@angelatlarge question as I see it now.

angelatlarge

@Kortuk Yeah, I guess that's a software question now.

@Kortuk Are you going to scrub up all the chatter now or leave it as is? Or will mods hold a conclave (in a faraday cage, of course) to decide?

Kortuk

@angelatlarge I will deal with it in a moment. I have to handle something at work first, but it is not productive, I have frozen it until I can react.

user61389

@angelatlarge I downvoted for his update 3.

angelatlarge

@CamilStaps I thought you were gone

user61389

@angelatlarge I'm back, muhahaha - I never said I went, by the way, did I?

angelatlarge

7:50 PM

@CamilStaps Maybe one of the wires in my brain got crossed

user61389

@angelatlarge it were just your wishes, sorry to disappoint you ;)

angelatlarge

@CamilStaps au contraire, monsieur, I need more beer.

But for now I gotta go, get stuff done. Cheers

user61389

@angelatlarge :) bye! Nice chatting with you

Kortuk

@angelatlarge Later mate!

@hhh If you need a moderator, do not use "@mods", we dont receive that, please flag the question.

jippie

8:27 PM

time for bed

/me is out

user61389

@jippie sleep well!

user61389

I'm going to talk a little with the guys on Philosophy and will go to bed then as well. Bye all!

jippie

1

Q: ATTiny85 not working after burning bootloader

I am having a problem with my ATTiny85. I should mention I use Arduino as an ISP to program it. My ATTiny worked fine until I decided that I need to step up the clock speed from 1MHz to 20MHz so I selected ATTiny85 at 20MHz from the Boards menu and then clicked on Tools>Burn Bootloader. But that ...

arduino attiny bootloader fuse

Please consider upvoting this question so the user can enter chat tomorrow.

Nick Halden

8:52 PM

@jippie DONE

BOOM

David Kessner

@jippie Upvoted, but do we really want Arduino people in the chat?!?! :)

rawbrawb

9:06 PM

@jippie same

@angelatlarge gave ya a star on that.

for the faraday cage comment!

Afnan Bashir

9:19 PM

can someone tell me that is there only proteus that simulates the microcontroller?

angelatlarge

9:42 PM

@jippie I might be predictable, but so are three other engineers walk into a bar...

Nick Halden

10:04 PM

@angelatlarge wait is this a joke?

tell me tell me tell me

whats the punchline?????????

TELL ME

@CamilStaps nice, you like philosophy? anything specifically?

angelatlarge

10:33 PM

@NickHalden It was a baaad joke

@NickHalden See what I was responding to, and then the line right above...

Nick Halden

@angelatlarge uhmmm im not getting it

angelatlarge

11:09 PM

@NickHalden He said something. I starred it. He said my starring is predictable. And I sought solace in the company of others by observing that other people starred it too.

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