Show Posts
Pages: 1 [2] 3 4 ... 7
16  Using Arduino / Project Guidance / Re: Detect the status of an exhaust fan on: June 09, 2014, 05:18:32 am
I would like to try sir goodhen's suggestion but I just want to clarify this... is the code the same for using the blade as interrupt (like this)and using a reflective material (like this)?

I guess the second one is what you need.

It could work with the first one, too. It's just a matter of how reflective the surface is. It needs to be so reflective that the bounced light is intense enough to register as logic level. I doubt using the adc is an option-it's too slow for this purpose. Using an opamp (or a transistor) would be pretty simple if the light levels are too low.
17  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 08, 2014, 09:33:13 am
Hi, I like the concept and the way you have approached it, good what you can get prototypes too, nothing flash just get the job done.
Great proof of concept and I wouldn't worry about over engineering, if its going to be handled a lot, that may be  in its favour.
Great idea.
Good luck mate.

Tom....... smiley

Thanks. You are right! Seems like I've even found the right batteries for it. Energizer L91-FR6 have 3000maHs and ~15 years shelf life.

Wow, good concept, nice project, obviously a lot of effort over some time. Thanks for sharing. Hadn't heard the line about the best watches being the fastest, haha!

No problems, thanks. Yea, I've made the first proof of concept about 3 or 4 years ago-that was without an RTC-that thing was running on an internal oscillator-I needed to manually compensate for the drift. I had this mechanism there that would round the time to the closest half hour when you held the button for a bit longer. smiley-grin
I am thinking about building a blind friendly binary clock next.  Something like this:
http://www.geekalerts.com/u/LED-Binary-Watch1.jpg

Only instead of the leds several buttons and a vibration motor. Once you press the button, it either vibrates (1) or doesn't (0). Might be used even by severely visually impaired people and it would have a fast readout and would be nice overall.

(Other than that, I am also working on a walking robot and several other things.)

Thanks for all the support! Really appreciate it.

Edit: as to this project: I will add custom color selection, readout speed adjustment and automatic ambient aware brightness correction (or how it's called). I'll just use the leds that are there, they are wired between 2 pins of the micro; they can be reverse biased and the capacity can be measured to obtain the ambient brightness info.
18  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 08, 2014, 06:31:54 am
Haha, thanks! Yea, works now. Seems like I overengineered it quite a bit, too. It's a clock-and I've done so far with energy saving that the batteries will die due to their shelf-life sooner then they will completely discharge. smiley-grin The estimated battery life, self-discharge included is ~25 years. Oh well. smiley-grin

I like to say that anything worth doing is worth over-doing! Sounds interesting, how about a brief summary of the project? 25 years, you must be kidding  smiley-grin

Nah! smiley-grin It's a clock project for my mum (or other people in need).
My mum is slightly visually impaired-she can't use normal clock and has to resort to her blind-friendly watch. However, she also has carpal syndrome and loses touch in her hand every once in a while, making it impossible for her to use it. Additionally, it's an old russian watch-and you know what they say about those. Russian watches are the best-they are the fastest.

(To be fair it's now about 30 years old and still going strong.)

Talking watch would be an option, but its annoying sound (for other people too), (presumably short battery life, I don't know) and price for a new piece make it a bit inconvenient.

I have thus decided to build her a clock she can use.
It blinks out a specific sequence in 3 colors. While she cannot really see small things, it is easy for her to tell the colors apart one another. This sequence is similar to roman numerals. 10s have a blue color, 5s have a green one and 1s have a red color. (To be user selectable in future).

for instance, 15:20 would be XV:XX in roman numerals. Here it is BLUE blink, GREEN blink (pause) BLUE blink BLUE blink.

The clock wakes up on interrupt and then goes to deep sleep mode. internal pullups are used, this being (presumably) the reason for slightly higher power consumption than estimated. Other reason could be the DMM inaccuracy. Even when a bit worse than expected, it takes about 4uA. When it powers up, it takes just about 5ma-the LEDs are pretty bright already at this level. If used once every hour, even at night, it will last about 25 years on 2xAA (which is a theoretical value, their shelf life doesn't allow for that).

Photos:
https://www.dropbox.com/s/c0tz15wyney93rd/P6060175.JPG
https://www.dropbox.com/s/887opqgtu8wwfwb/P6060176.JPG

Remarks: Yea, that's a fingerprint. I didn't wash off the photoresist, because I like how it looks. Then I touched it with alcohol on my hoof.

Yea, the button is humongous. Couldn't find the one I've designed it for. It's supposed to be something like this:
http://static2.tme.eu/katalog_pics/b/5/a/b5a8fd5059671d5d753a73c6a25fb128/tact-24k-f.jpg

The bulged resistors are supposed to be one smd resistor, but I didn't have one.
The 2 wires (black and red) are not supposed to be here; it's designed for THT battery holders; again, I didn't have those.

The bypass capacitor is a bit far away from the clock chip; whatever-in the datasheet, it doesn't even mention you should put a bypass cap there (AFAIK) . I guess it has such a low current draw the stray capacitance is enough.

The 2 jumper wires on the other side are not necessary; they were added as an afterthought. Will remove those in next revision.

I am planning to get a thin piece of something (cardboard, plastic?) laser cut. It will have holes for the LED and the button and will protect the smds. It will be glued on the upper side of the board.

This is the 3rd prototype of this device; I think it's pretty much ready for larger production-would be interesting to target this niche market with something like this-it's very cheap to do, even with the work, I could sell it for ~$10-20.

I have done 2 similar devices. One is this one http://www.instructables.com/id/Schematics-n-stuff/
(bit of a proof of concept, pretty old too)

And one is the aforementioned clock with 36 leds.
19  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 08, 2014, 02:19:03 am
Quote
It's Pro'skit solder paste. A warning comes with it. "This solder paste is not suitable for the soldering point on Integrated Circuit or high voltage (frequency/power) You are suggested to clean the soldering point by ethyl alcohol after using in order to avoid the possible short situation."

Hi, a poltergeist in the machine!!!!!!!!!

Good to hear you got it sorted, I'm sorry but I don't know of any good hair restorer.

Tom.... smiley

Haha, thanks! Yea, works now. Seems like I overengineered it quite a bit, too. It's a clock-and I've done so far with energy saving that the batteries will die due to their shelf-life sooner then they will completely discharge. smiley-grin The estimated battery life, self-discharge included is ~25 years. Oh well. smiley-grin
20  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 08, 2014, 02:15:11 am
I was beginning to wonder about that, and it's one thing I hadn't tried, was to make sure the input power supply was robust enough. A pair of fresh AA alkaline cells evidently aren't good enough. Thanks, I'll play with it!
Hi, no problem. I believe this is the solution-at least, it worked for me when I was powering 12 RGB LEDS. Although I didn't have all of them on at the same time (with all colors) and I am not sure about the actual current flowing through there, they sure do light up brightly, so it should be giving out a lot of juice. I actually had problems with it before I've added the huge caps and they solved the issue, so it may be the same for you.
21  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 07, 2014, 02:59:28 pm
Glad you got it solved, that was a tough one! Be sure to let me know if you ever manage to get 350mA out of a MCP1640 (as advertised by the datasheet) -- this is the only way it's disappointed me. I can get reasonably close to that, but only if I ramp the load up slowly. But it won't start properly (never gets up to voltage) into a load that needs more than about 150-175mA. Anyway it works well for applications that need less current than that.
Haha, yea! Thnaks If it wasn't, I wouldn't bother these forums with it. I am self taught and I don't like asking for advice-I usually want to solve everything on my own.
I have sort of managed that; you have to connect it to a huge bypass capacitor, wait a bit and then connect the load...

Edit: In my case (~350mA): 100uF+2*4700uF

Edit2:  I use the version that connects Vin to Vout when not enabled. So the caps get charged a bit before it starts; the transition is then not so hard, it doesn't go into full short circuit.
22  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 07, 2014, 02:39:46 pm
"This solder paste is not suitable for the soldering point on Integrated Circuit or high voltage (frequency/power) You are suggested to clean the soldering point by ethyl alcohol after using in order to avoid the possible short situation."

Wow. I'd sure be ditching that stuff immediately. Maybe it could be used for copper plumbing.

FWIW, my favorite

I gotta say It works really well-the consistency of the solder gets really really nice and it doesn't stink... But yea, it must've been the cause of the issue... I've desoldered the resistor, slid my soldering iron between the 2 pins, it made "vssschcchhchch" and it works like a charm now. Thanks for the tip and ongoing support though!
23  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 07, 2014, 10:45:12 am
Okay. The EXACT SAME CHIP (not just the same number), placed deadbug style on ABSOLUTELY RIDICULOUS layout, soldered with no flux works. So... Am I going crazy? Or is it leakage?

Back to the PC board then. It's either layout or an error (design or manufacturing) on the board. What software was used to create the board? I did not check it 100% against the schematic (that's a job for software).

I doubt that residual flux will cause significant leakage, especially on a newly assembled board. Easy enough to remove that possibility though.

Hello! Sorry about the misconception. When I've changed the resistor for lower output voltage, I have actually replaced it with a bad one. (3 orders of magnitude lower, my bad). The board is newly assembled, but home etched. I have replaced the resistor with one that would give me ~3.3v out. While doing so, I have noticed there is a bit of flux residuum between the 2 pins. I've got rid of that. It now gives 3.4-3.7v. That is > vin and relatively close to expected voltage. Must've been the flux. It's Pro'skit solder paste. A warning comes with it. "This solder paste is not suitable for the soldering point on Integrated Circuit or high voltage (frequency/power) You are suggested to clean the soldering point by ethyl alcohol after using in order to avoid the possible short situation."

So... yea.
24  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 07, 2014, 04:21:28 am
Not all smd resistors are manufactured equal, I have had a spool of 3k9 smd in a production run that measured okay out of the spool, BUT jumped to over 10K when you soldered them in. Got suspicious when the conductive ends of components started PEALING off the component body.

Hope you sent 'em back. Sounds like defective material, assuming the soldering process was within spec.

Okay. The EXACT SAME CHIP (not just the same number), placed deadbug style on ABSOLUTELY RIDICULOUS layout, soldered with no flux works. So... Am I going crazy? Or is it leakage?
25  Using Arduino / Project Guidance / Re: What are the ways to transfer data from arduino ?? on: June 07, 2014, 02:46:14 am
The cheapest way I could think of would be using these:

http://www.ebay.com/itm/4pcs-NRF24L01-2-4GHz-Antenna-Wireless-Transceiver-Module-for-Arduino-New-T1K-/141130844621?pt=LH_DefaultDomain_2&hash=item20dc0dc9cd

(I've bought similar ones, didn't get to testing them yet... But allegedly, they do the job.)

Use Arduino on PC side.
http://www.ebay.com/itm/Sale-Geeetech-Chinduino-Duemilanove-Atmega328p-pu-compatible-with-Arduino-IDE-/281317697348?pt=LH_DefaultDomain_0&hash=item417fd76744

26  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 07, 2014, 02:42:24 am
http://www.tme.eu/cz/Document/76aa6f2e4800aa20668de5274e067fd8/dla_a.pdf

This one-it has worked with this chip before. The esr is slightly higher than recommended, but even when I tried 2 in paralell, still no luck.

I'd say that at 1Ω, ESR is more than slightly higher than recommended. It's high at least by a factor of 3 to 5, and it's not hard to find inductors with 1/10 of the ESR. It's current rating is pretty low too, only 190mA. MCP1640 datasheet says inductor current can be as high as 800mA.

Here is the part I use, although I've also tried several other quite similar parts with essentially identical results. ESR is 0.07Ω and saturation current is 2A.

You say it has worked in the past, so I cannot argue, but I do wonder what else might be different. I'd think an inadequate inductor might work fine at no load or small loads (e.g. 1-2mA) but then I would expect output voltage to fall if too much current is drawn. At least that has been my experience. So I'm still scratching my head.

Exactly; The worst ESR out of the inductors the datasheet recommends is about 0.5. Now that is for full power, 5v, 300ma. "My" ESR is 2 times worse (now the same, 2 inductors in pararell, inductance halves, still in limit), but the current I am trying to draw is <30ma.

I've had success powering 36 leds with this inductor; I had to use huge caps for bypassing, but it worked. (Yea, yea. I know. Not a sensible design.) That was about 300ma, pushing it to the limit. Only problem was a voltage drop, which I had to resolve with the aforementioned bypass caps.

I am starting to think it's either too small ground return path or leakage currents. I will build a DC/DC converter with those parts. A standalone one, similar layout. We'll see.
27  Using Arduino / Project Guidance / Re: Help with remotely controlled pet door on: June 07, 2014, 02:32:23 am
Quote
If I don't use the mechanical relay, how could I wire in the MOSFET instead?
Thank you for your ongoing assistance.

You might be able to just use a small NPN transistor in parallel with the switch somewhat like below. Use a digital output pin on the arduino to activate the transistor base..



Using an NPN transistor may work-but I am not sure about the diode. Plus, keep in mind that the pinout of these devices is not unified. smiley-wink

Edit: Um... wait, this drawing isn't a drawing of his setup, is it. It's just something similar?
28  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 07, 2014, 02:29:18 am
Hi, have you measured the values of your resistors?
Not all smd resistors are manufactured equal, I have had a spool of 3k9 smd in a production run that measured okay out of the spool, BUT jumped to over 10K when you soldered them in. Got suspicious when the conductive ends of components started PEALING off the component body.

Tom....... smiley
PS, have you checked with the scope , your input power trace?
If scope shows 6V with 0.1V ripple, why does DMM show 8V, DMM battery low, try another DMM.
I agree 0.1V is a bit high.

Edit, your PCB pattern has a connection to pin1 that goes from a relatively wide trace to a very narrow, have you tried making that thin trace bigger, even with a bit of wire, it will be introducing significant series resistance I bekieve.
Sorry about the confusion. I sometimes get as close as 5V, sometimes 8. It depends on the load. The DMM measured the same value as my scope at the time I checked it. You could be right about the trace.  I have etched 2 boards, one of which didn't turn out really well (made a mistake in the design). I will try to build just a standalone DC/DC converter board out off the first one.
Due to the high values of the resistor, there might be a flux residuum causing a problem there somewhere (leakage current). I mean, I've cleaned the board, but one never knows.
29  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 06, 2014, 01:57:00 pm
Continuity tests ok, capacitors are there, the inductor seems fine, plus I have used the exact one before and it worked just fine.

You used the same inductor before?
For what? With an MCP1640, or for something else?
Got a part number or link to the inductor?


http://www.tme.eu/cz/Document/76aa6f2e4800aa20668de5274e067fd8/dla_a.pdf

This one-it has worked with this chip before. The esr is slightly higher than recommended, but even when I tried 2 in paralell, still no luck.
30  Using Arduino / Project Guidance / Re: MCP1640 boost regulator outputting 8 volts?! on: June 06, 2014, 10:40:48 am
Have a spare MCP1640? I might just try replacing it.
Aaaand... Nope. Didn't help. What the actual...
Edit: And neither does connecting another inductor in pararell (esr drops, inductance stays in limit, but nope) or removing the filtering capacitor.
Edit 2: ANGHHTHHTHT!!!!!!!!!!!
I CHANGED THE RESISTOR! NOW IT SHOULD GIVE EFFIN 3.3 VOLTS, BUT GUESS WHAT?!?! IT'S EVEN WORSE! 8 volts all the way. omg
WHAT IS GOING ON WHAT IS GOING ON WHAT-IS-GOING-ON WHY WHY WHAT
Pages: 1 [2] 3 4 ... 7