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1  Using Arduino / Project Guidance / Re: Arduino "Swamp" cooler/heater control? on: May 16, 2013, 10:16:32 pm
I'm coming to the same conclusion reading up on PID......  simple step points are much easier to code. PID is just overkill for the application.
2  Using Arduino / Project Guidance / Re: Arduino "Swamp" cooler/heater control? on: May 16, 2013, 09:38:11 pm
For me the biggest issue is the disconnect between the cooling system and the heating. If both thermostats temp sensors read the same or even were off by some set amount I could probably stagger them (IE heat to 70  and cooler to 72) but they just don't. Having one homogenous system controlling both is the only fix I can come up with. The averaging is because the house was built in 1942 so some rooms cool faster than others.

Also in hopes of battling that is the idea of the vent baffles.... closing off "zones" as they get to temp but hold the furnace running until the remaining zones catch up or some such.

Now for the programming fun..... I'm off to research this "PID" thing...........

3  Using Arduino / Project Guidance / Re: Arduino "Swamp" cooler/heater control? on: May 16, 2013, 08:18:48 pm
I just ordered some one-wire temp sensors (Which conveniently come in a sealed metal tube that's about 1/4x4" for poking through the ceiling) and two relay boards, one 4 and one 8 channel. The relays are rated 10A/250V which should be plenty.

Gist of the plan is to use 5 temp sensors and average them (Mostly for future development) to get "House temp" and then control the 4 relays to select Fan High, Fan Low, Water Pump and Heat. I just have a regular old gas fired furnace so on/off is all I can really control of that. It wouldn't seem to be that hard to add a humidity sensor and add in heat pump/AC Cooling too. It's another "stage" to work in but nothing that sounds too hard.

Later development may include vent baffles to control floor vent volume so I can do "Zone control" (I was looking at 12V car door lock actuators... only $6 @ Amazon). That will come in to play later once I get a basic temp control system in place.
4  Using Arduino / Project Guidance / Re: Arduino "Swamp" cooler/heater control? on: May 15, 2013, 10:49:40 pm
Now that is interesting.... I wonder if it's a code (as in building code) thing because I've looked and shopped controllers a couple of times and they all have been mains level voltage. (Home Depot, Ace etc) (Denver CO here).

Is there some kind of module in the roof mounted cooler itself? Hmmm, I'd have to rewire a direct line but overall that's pretty easy. For that matter, I could mount the relay module in the cooler and use the same principle that way too. (BTW, reading up on SSR's indicates they aren't so hot for inductive loads like the motor. Good ole fashioned relays will do fine.)

The one I have now is digital, with an adjustable on temp but you have to set fan high/low and pump/fan manually using switches. The one before this one was a rotary temp dial but it automatically switched between high and low fan. I liked that, didn't like that it wasn't calibrated so any given position on the dial was at best a wild guess.

I'll look in to the remote possibilities, it may indeed be easier.

5  Using Arduino / Project Guidance / Arduino "Swamp" cooler/heater control? on: May 15, 2013, 03:35:48 pm
An evaporative cooler (AKA "Swamp" cooler) for those who aren't familiar are devices used in dry climates that basically suck dry air through a sponge like material saturated with water. Evaporation in turn cools the air which is then pumped in to the house to cool it. They use about 10% of the electricity of a traditional air conditioner.

The problem: there are no commercial controllers that intelligently juggle both the evap system and the furnace at the same time.

So, when you feel cold you turn on the heat. As it starts to heat up the evap cooler you forgot to switch OFF (Or perhaps more accuratley your wife  smiley-eek-blue) turns on to try and cool it down.... and they both go to town battling each other until you wake up in the middle of the night to find out it is either freezing or muggy and hot as hell. (DAMHIK).

Annnyyyyway...... LOL, this sounds like a great Arduino project.

The cooler is directly controlled via 120V AC and has Fan High, Fan Low and Pump feeds. The furnace I think has the usual 24V (AC I think?) on/off circuit.

Unless I am missing something basic, an Arduino, a temp sensor and 4 SSR's and that should be about it? I Haven't used SSR's before... any caveats to watch out for? (I am comfortable wiring 120V AC circuits.)


6  Development / Other Hardware Development / "Nano Shield" for SimpleSDAudio library.. SD card and audio amp. Pls review on: January 07, 2013, 06:42:50 pm
I have been working on a "shield" for the Gravitech Arduino Nano that will read from an uSD socket and play the audio through a 2W audio amplifier. (More will be added later, but I hope this is a useful sub-project for someone.)

For now, if anyone is just dying to go over a newbs work to look for flaws  smiley-evil please do so.

Attached are the schematic in PDF format, as well as the Eagle 6.3 files and here are the datasheets to the major components.

Arduino Nano



Even just a quick check for bonehead errors is appreciated! It does pass Eagle ERC and DRC so hopefully it's not too bad.

Anyone reading this later THIS IS AN UNTESTED/UNPROOFED/UNPROVEN design. DO NOT USE.

Thanks in advance!
7  Using Arduino / General Electronics / Re: Is this utterly wrong? on: January 05, 2013, 10:57:35 pm
Now that is interesting. Had no idea it worked that way. My mind was blown when I found out electrons flowed from negative to positive too.
8  Using Arduino / Project Guidance / Re: OK, Nano..... how low can you go? (Or.... "Can Atmel limbo"? on: January 04, 2013, 10:56:41 am
I'm designing a board intended to be a lightsaber "shield" for the Arduino nano, (.7" x 2.25" Hopefully) which will house a microSD card, accelerometer, audio amp and 1.X amp PWM controllable LED driver.

People regularly choose 1x L-ion, 2x Li-ion or 4x NimH batteries. (They most readily fit inside a lightsaber "hilt".)
I would (and will) include a switching regulator if space allows but the board is small.

It may be better/easier to indicate they need a step down for 2x Li-Ion, a step up for 1X and are probably OK with 4x NimH. As you point out they are easy/cheap on Ebay and you can customize it to fit the need.

Anyway, the idea is using off-the shelf components and with freely available files (Eagle, gerbers, code, etc) so anyone can build thier own or modify it, etc. While there are commercial options out there none are fully programmable like the Arduino which I think will appeal to some designers. In my case, I want a full color lightsaber and nothing else controlls RGB, LOL. (The WIIFM... ;-)
9  Using Arduino / Project Guidance / Re: OK, Nano..... how low can you go? (Or.... "Can Atmel limbo"? on: January 03, 2013, 08:50:06 pm
True that.... handfull of chips and a custom board or two and even if it fails utterly I'll learn a lot.

10  Using Arduino / Project Guidance / Re: OK, Nano..... how low can you go? (Or.... "Can Atmel limbo"? on: January 03, 2013, 06:54:56 pm
Does anyone have real world experience?

I have ran those chips safely from 2.5v to 7v.

@ 16 Mhz or did you have to drop to 8Mhz at the lowest V?
11  Using Arduino / Project Guidance / OK, Nano..... how low can you go? (Or.... "Can Atmel limbo"? on: January 03, 2013, 06:50:26 pm
The specs on the Nano says that it takes 6-20v.

Bypassing the Vreg and supplying your own 5V, you can get down to 5v

4x Nimh Batts are ~4.8V...... close enough? How about 1X Li-Ion cell at 3.7V?

I am trying to design a simple shield that will be battery powered and would love to not have to build in a boost converter if I can get away with it. I've been reading the datasheet and the charts aren't exactly high precision... LOL.

It lists 2.7v as "safe" to 10 Mhz, and 4.5v as safe to 20 Mhz......  10 Mhz over 1.8v...  0r .18v/Mhz. 10 Mhz @ 2.7v plus .18v x 6 Mhz... 3.78v as a bottom end safe voltage @16 Mhz? (It's probably not exactly linear.... but it's something to guess on...)

My take.... 4.8v is just fine..... 3.7v is really pushing it. Dang it, so close yet so far... LOL.

Does anyone have real world experience? I'm hoping that the "Safe operating voltage" means it may cough and screw up once in a blue moon but will basically be just fine.

12  Using Arduino / LEDs and Multiplexing / Re: High power LED drivers.. 2A, 10W plus, PWM control & low(er) heat? on: January 02, 2013, 01:40:53 pm
Hmmm, another candidate....

ST Micro LED2000

Up to 3A, high effiiciency.... available in SO8

I can't really find any faults except maybe that it does need a kind of large inductor.

13  Using Arduino / General Electronics / Re: Small logic level converter for SPI? on: January 01, 2013, 10:39:59 pm
Good point.... the hope is to make something open platform available for lightsaber builders. (Yes, there are folks who spend way too much time and money on this, LOL.)

To that end.... bulletproofing the design where possible is a good idea. Plus, as noted.... the TXB is absolutely adequate for the need, buffers all the lines and fits the size and solderability requirement... winner!

14  Using Arduino / LEDs and Multiplexing / Re: High power LED drivers.. 2A, 10W plus, PWM control & low(er) heat? on: January 01, 2013, 10:29:52 pm
Yes, that drives the LEDs, but part of the "illusion" is carried by ramping up the light so it appears to extend down the blade, adding a pulse or shimmer effect when the blade is extended, a flash coinciding with an impact and blade retraction effects (etc.) so the PWM control is part of the whole package.

My main goal is to make an open platform lightsaber controller available... there are commercial controllers out there up to $150 or so but not much for folks who would brew thier own. It will be larger than most "pro" ones but being programmable opens a lot of possibilities (hopefully some of which I haven't though of, LOL.)

Dhenry, looking at the Simpleswitcher... it may be a winner.
15  Using Arduino / LEDs and Multiplexing / Re: High power LED drivers.. 2A, 10W plus, PWM control & low(er) heat? on: January 01, 2013, 08:13:38 pm
I'm trying to design something that will work with several LEDs, although it will start with a single driver under PWM control. The eventual goal is a "shield" designed to fit on an Arduino Nano. (LED Driver, microSD, Accelerometer, Audio Amp)

The idea being is you want just a single color LED the driver will be on the board. (If you wish to drive RGB(A) then you would add on a 2x or 3X driver sub-board.) Most folks would just want to drive one LED.... somewhere between 350 ma to 1200 ma.

My personal favorite is the RGBA by Ledengin (Red, Green, Blue, Amber)

@1000 ma
R 2.4v
G 3.7v
B 3.7v
A 2.7v

Although I was running mine using the STCS2 @1200 ma. (I'm OK with a lightsaber LED that only burns for thousands of hours instead of 10's of thousands. ;-) 4xAA Nimh Pack so 4.8v source.
(Opps.. meant to include link to LED.)
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