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16  Using Arduino / Project Guidance / Re: How to Waterproof TMP36 temperature sensor? on: June 17, 2013, 08:06:05 pm
Nicks idea is best but if you  already have bought them then just coat them with epoxy like the manufacturers do... are you sure that they are not already water proof?
17  Using Arduino / Sensors / Re: Thermocouple + MAX31855 + Arduino--SPI wiring Problems on: March 28, 2013, 07:48:02 pm
You should not have done any harm  unless you connected the MAX chip directly to the 5 volt outputs of the Arduino.  What voltage are you reading across the MISO connection? Do you ever get any other reading than the base reading?

18  Using Arduino / Project Guidance / Re: K Thermocouple+MAX31855+Arduino Mega Problem-PLEASE HELP ME!!! on: March 26, 2013, 05:22:01 pm
I had a similar problem even when all the connections were soldered to a perf board. I think this chip is very sensitive to noise. I added some extra bypass caps but that did not improve much. I went to much higher temperatures than you did and got larger swings as the temperature increased. Also got some very high and low spikes. As the temperature went up, the readings were pretty much where they should be but drifted high and low in sort of a random way, so the chip was working but picking up noise somewhere.

I was told that the voltage divider might be the problem and maybe a level shifter might do better, but I never tried it.

Hope you have better results than I had.
19  Using Arduino / Sensors / Re: Thermocouple + MAX31855 + Arduino--SPI wiring Problems on: March 26, 2013, 01:13:42 pm
The reason I said this is because I checked all the connections and they looked good, but the damn thing still didn't work. What happened is that I put just enough pressure on the open pun, to have it make contact with the solder beneath it. When I took off the probe, the pin opened again.

I probably would still be scratching my head except I saw the Arduino readout change if I pressed on the chip.

I had no problem with the 3.3 out to the Arduino. but I fried a chip by allowing 5 volts in, so make sure you use a voltage divider or level shifter.

Even after I got things running I still had problems with seeing large swings in output that got worse as the temperature rose. I never did track it down. I went back to using a AD595 that had no stability problem.

 
20  Using Arduino / Sensors / Re: Thermocouple + MAX31855 + Arduino--SPI wiring Problems on: March 25, 2013, 04:41:18 pm
I would make sure that you  have a good solder joint in the SOIC to DIP. use a straight pin contact to the top of the pins of the SOIC  and the regular lead to the DIP. so that you are seeing if the continuity is there. I found an open this way that was pretty elusive.
21  Community / Exhibition / Gallery / Re: Glass Kiln Control on: January 17, 2013, 09:03:14 pm
are you using the MAX31855 chip the older MAX6675. I have built kiln controllers with both and I am having stability problems with the MAX31855 chip that I didn't have with the MAX6675. the 31855 displays rolling temperature oscillations around a correct average that increase as the temperature gets higher. it seems like the fluctuations are around 10% of the actual temperature.   Also I see random scrambled readings. 

I have also used AD595 chips, and have had no problem... nice and quite. Have you run into this problem while you were shaking out your system?

I hope you can get the bad links back on line, I'd like to see your code.

I use a laptop to control and log the the results of the run graphically. If you are interested in trying it I'll send you the app and the Arduino code I am using.
22  Topics / Science and Measurement / Re: Due A/D Speed Question. on: January 02, 2013, 02:50:23 pm
The 1.0.3 IDE does errors out on both the array size and the call  analogReadResolution(12)

  where did this guy come from ? analogReadResolution(12);
23  Using Arduino / Project Guidance / Re: Auto-Range Capacitance Meter on: December 30, 2012, 01:57:11 pm
got the following grouchy message when I tried to open your link
Quote
Forbidden

You don't have permission to access /en/Tutorial/CapacitanceMeter on this server.

Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request.

the circuit is simple enough, maybe the easiest thing is to bread board it and see how it works if you have the script to calculate the timing.
24  Using Arduino / General Electronics / Re: Innacuracy in converting thermistor resistance to temperature. on: December 12, 2012, 12:44:25 pm
 in theory, an accurate three point calibration of T verses R should allow you to solve for the a,b,c coefficients of the  Steinhart–Hart equation. You need to bracket the temperature range you are interested in.

I have never done this because it requires solving three simultaneous equations, and I never had requirements for that kind accuracy. I could usually get away with introducing a linear "fudge factor"

The only point I was trying to make is to be careful that the tool you are using as a standard of measure of temperature is accurate.
25  Using Arduino / General Electronics / Re: Innacuracy in converting thermistor resistance to temperature. on: December 11, 2012, 05:51:56 pm
I would take what dc42 said seriously about making sure you have a correct temp standard to calibrate against..I have been playing around with thermocouples for quite some time and have found that the difference in readings from one to another can vary quite a bit more than specs.
If I want to do a calibration, I use a very accurate mercury thermometer. I usually take an ice point ( 0c) and a  boiling point ( which will vary with external pressure but  can be calculated) and they do not drift or pick up noise like some of the electronic devices I have tried.
26  Using Arduino / Motors, Mechanics, and Power / Re: Quick question: Did I kill it? on: November 23, 2012, 02:23:46 pm
If it worke once and now it doesn't... well something bad happened!

If the stencil for voltage on the bottom of the PC board is  backward from the top, then I think you should get your money back... although it looked OK on the link you gave.
27  Using Arduino / Microcontrollers / Re: Help with a potentially burned Arduino on: November 18, 2012, 12:23:36 pm
Quote
Edit: I forgot to mention that the thing 'died' when the current program (a simple relay 1 through 4 'ON') ran for its first and only time so far and the screen dimmed quite a bit and after unplugging and replugging the USB cable the thing flat out refused to start

Sounds like maybe a lot of current went across somewhere.

Did you try unplugging all the stuff and just trying to get the bare board to work?
28  Using Arduino / Motors, Mechanics, and Power / Re: Solid State Relay Problem on: November 12, 2012, 04:50:40 pm
Don't give up too soon. As Grumpy_Mike says just wire a 120 volt light bulb through the relay and put a 5 volt battery across the digital in.

If you can toggle the light bulb on and off the relay is working.

If it's working then either you are not getting a high enough voltage to the digital in or you may have wired it backwards.

I have discovered that, even with no digital  input signal , the reading across the output will sometimes read 240 v. It's just that there seems to be a small leakage current, but not enough to drive any thing.
29  Using Arduino / Project Guidance / Re: Mind Controlled Robot on: November 12, 2012, 04:37:07 pm
Based on videos I have seen of robotic hands created by research workers, I would say you have have bitten off quite a hunk. The videos show multiple complex servos or steppers all working in concert. A robot with articulated hand(s) is even a bigger hunk.

What I would do is start out by thinking about  the minimum function you would need for just the hand and work on the mechanics first, keeping in mind what electronics might be used to make it work. Then you can come up with the logic to move the hand.

I don't know the capabilities of a  mindflex or its' output, but I think that is the least of your worries.
30  Using Arduino / Project Guidance / Re: First Ardiuno Project Mosfet Inverter on: November 12, 2012, 04:22:24 pm
The code will toggle pins on and off but I am not sure you will get 8.333333 mS accuracy in the toggles.
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