Must-haves for EASY DIY controller?

terahz, I did use the one you guys put online ... is it the one you use for the PH ?
Did you try on temperature ?
Right now I did not connect the PH prototype to my digital board ... just analog prototype and I did put that on my temperature chamber.
 
nauticac4 said:
Has anyone sent the board to be prototyped?. I was thinking of burning a few bucks and ordering boards for the Cat4101 Driver and I figured while I'm at it I'd take a crack at this one as well. Didn't know if the Eagle files on the Code site had any known problems. Haven't been able to look at them because I am at work.
Click to expand...

I've still got a stack of the prototype PCBs. If anyone is seriously interested in helping with development, shoot me a PM and I'll mail a board (when I get to the PO, which is only about once a month). There are at least two "serious" faults with the Ethernet section of the circuit, though they can be fixed with bits of wire. There have been a few other convenience changes, but nothing else serious. And there may be other problems with the Ethernet circuit since it isn't actually working yet. . .

theatrus said:
Do you have an off the shelf enclosure in mind? It would be nice to mount it in something available like a Polycase box to protect it.
Click to expand...

Nope but I'd imagine it would be easy to find a project box that it fit in. I tried to keep "connections to the outside world" (Ethernet and pH) along one side so that side could be mounted appropriately aligned with holes in an enclosure.

terahz said:
Does anyone know how long is the battery supposed to last on the hydra without any power for a long time? I unplugged mine Thursday night at 3.3V, today I get 0V. I have no idea how long when the battery died, but if it lasts only a couple of days, that doesn't seem right.
Click to expand...

Yeah, there's something weird going on there. The power consumption when asleep is tiny. Sparkfun claims their board (which uses a slightly larger battery IIRC) last like 11 years or something. Could you have bad batteries? Or a fault in the board? Mine's been in for months and it still reads 3.295v.

OTCHU said:
terahz, I did use the one you guys put online ... is it the one you use for the PH ?
Did you try on temperature ?
Right now I did not connect the PH prototype to my digital board ... just analog prototype and I did put that on my temperature chamber.
Click to expand...

Yeah, the circuit we have on the google code site is the circuit in use. You're talking about problems at different temperatures, and a temperature chamber - I'm a little confused - what sort of temperature range are you testing over?
 
I'm interested in helping to develop the project just don't know if my soldering skills are up to par yet. Got a lotta good practice in this weekend though. DWZM sent you a PM
 
Sorry if sometimes my english is not the best !!! lol

I did test the PH circuit between 40F and 100F and the output had about 30% of variation between this both temperature. I think 10% will be acceptable but 30% is pretty high, no ?
 
just the circuit board. The probe and the power supply was out the temperature chamber. I have to solder more wires on each output of the amp op to check witch one go wrong
 
Check temperature coefficients on your components. Caps can have HUGE value swings over a temp range like that. I don't have a solid understanding of the theory behind this stuff, but I did carefully look at the specs when I put that BOM together. It's worth noting that my BOM is different components than terahz's original BOM though.
 
The caps aren't going to do it here (a changing time constant isn't going to affect anything). My bet: the trimpots. Trimpots are eeevvilll.
 
Could one rule that out by measuring resistance on the trimpot under different temperature conditions?

At any rate, assuming the device is calibrated under "real world" conditions with the Hydra at "operating temperature" then I don't think it'll be an issue.
 
der_wille_zur_macht said:
Could one rule that out by measuring resistance on the trimpot under different temperature conditions?
Click to expand...

Yes. Looking at the datasheet for your trimpot, the tempco is 100ppm, which isn't bad. However, that assumes the wiper doesn't move with temperature.

der_wille_zur_macht said:
At any rate, assuming the device is calibrated under "real world" conditions with the Hydra at "operating temperature" then I don't think it'll be an issue.
Click to expand...

My room environment, while not climbing to 100F, would likely dip to the 50s easily.

There are ways around this:
- Glue the pot in one position (if its wiper drift)
- Digital calibration. Requires some non-simple math to calculate. This is the approach taken by most controllers.
- On-board temperature sensor + calculation
- Use a cheap DAC as the offset voltage generators (MCP4728 is great for this).
 
Ok regarding my battery issue, there is a short somewhere. I get 1.2mA draw even with the power supply connected. the chip is supposed to draw 500nA (as per datasheet) and I'd guess only if there is no power available... Can anyone measure theirs and let me know what they get?

As for the PH circuit, we might have to add some software compensation for temp variation. I think that is how all digital PH meters work...
 
Hmm, is the VBAT supposed to be connected to VCC when the chip is on? That's what I see on my board. When I plug in the USB or wallwart VBAT becomes connected to the +5V rail, when it is off, I can't find any shorts with the multimeter nor visually. Either way, the current draw is not different with or without external power. Maybe my DS1307 is busted, I'll see if I have a spare and give it a go.
 
danzada said:
Hi all.
I hope I'm not interapting, but I have a question.
I bought the following SSR's (for reef controller project), and I think I did a mistake:

http://cgi.ebay.com/SSR25A-SOLID-ST...ontroller-/120584707970?pt=LH_DefaultDomain_0

Are these SSR's trustable? Can I sleep quietly with these SSRs running?
I'm going to connect pumps, skimmer and 300W skimmer (all 220v).

What do you thinik?

Many thanks!
Dan.
Click to expand...

Good news - the RU (UL Recognized Component) mark is legitimate on that product.

http://database.ul.com/cgi-bin/XYV/...n=versionless&parent_id=1073763379&sequence=1

Of course that only means the component is safe - how you use it may not be.
 
I think that maybe an expensive approach to controlling outlets. Look back at this post by terahz
terahz said:
I worked a bit on the relay part of the controller so here is the progress.

2x opto-isolated 10A 4 relay board from futurlec
http://www.futurlec.com/Opto_Relay_4.shtml
1x American DJ power strip
http://www.amazon.com/American-DJ-P...8&s=musical-instruments&qid=1278899261&sr=8-1
1x MCP23008 port expander (same as on the controller)
http://mouser.com/ProductDetail/Mic...3008-E-P/?qs=sGAEpiMZZMvcAs5GUBtMdVgPLCS8TUZv
...
Total cost for 8 controlled 10A outlets comes to a bit over $60. Not bad imho.
Click to expand...
Yes, I left off a bunch of pictures and descriptions. And I guess I should qualify it depends on how many outlet you need. The only thing I will change (if I can) will be to have shorter wires from the relays to the control board. I intend (does anyone know if I can) to have a long IIC bus, 12 volts (for the relays) and 5 volts(for the port expander). Four long wires of moderate gauge rather than 16 heave gauge.

[EDIT]
Oh, that sounds critical. I didn't mean to. It is the same idea (a good one) just a different approach.
 
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