Crab conditions controller... again!!!

[Ryanstein]

Just to let everyone know who was following this months ago, the project is NOT dead...

Here's the original topic: viewtopic.php?t=63101

I've redesigned the entire circuit almost 4 times now, and added loads of new features. Currently (as of yesterday) I'm prototyping and testing the circuit section by section... starting with the digital thermometer:



The board the circuit is built on is called breadboard. Basically, it's a super easy way to build and test temporary electronic circuits, and can then be pulled apart later. Just to note: the display is reading 21.8 degrees Celsius; the way the breadboard is designed forced me to cascade them vertically. In the final version they won't be like that.

Here's a close up of the display:


And finally... a close up of the 'chip' (or integrated circuit) that's doing the majority of the work:


I forgot to take a pic of it... but the sensor itself is the tiny black dot beside the blue square with the white circle

The final product will be a digital thermometer, digital humidity meter, and (hopefully) digital pH meter as well. The circuit will be capable of turning heaters and water misters on or off in order to maintain specific conditions, and automatically control the lighting, starting dim in the morning, bright midday, then becoming dimmer again towards nightfall.

More updates to come!!

[Ryanstein]

***UPDATE***

So yesterday (late-ish last night) my friend came over and helped me build the pH measurement part of the circuit. So far, though the calibration is horrific (I don't have any buffers to calibrate to, but will ask for some at school on Monday ), it is semi functional, giving a higher reading for basic solutions, a far lower one in in acidic solutions, and about 7 in water.

Anyway, once the pH circuitry is done, I'll move onto the humidity measurement section. As well, I've started the counter circuit, which will drive the lighting for different brightness levels throughout the day, pumps for tides, and my bubbler.

More to come in the near future!!

~Ryan

[Ryanstein]

OK... still working on it... and have been several times a week.

I am drawing the schematics right now... and I finished the first one, with the display readout and controls. Just to give you an idea of why it's taking so long... just that one circuit board (1 of 5 in total) has over 150 electronic components on it, and the schematic itself consumes an entire 8.5 by 11 printer paper.

The board in my previous post ^^^ is now completely covered in parts, and I had a second board of the same size, which is also completely covered in parts. And I haven't even finished it yet...

Here's a comprehensive list of its functions & features:
- 2 Timed outputs, where two features can toggle back and forth (total of 4 actual plugs). One has a pump pulser.
- 1 Lighting output, which varies the intensity of a light according to the time of day
- 1 Heating output (connected to internal presettable thermostat)
- 7 Probe inputs (temperature probe, humidity probe, maybe salinity in the future)
- 1 pH probe input
- User can select which of the 8 inputs is to be shown on the LED Display.

More updates to come

[Ryanstein]

I just finished exams a week ago, and have been working furiously on this project day and night (don't tell my mom...), and I had a breakthrough a day ago with the pH... so it can now read pH and temperature, and humidity will be on the way (I just ordered new sensors.... they cost a fortune at 17$ each ).

And I've changed the design again

There are two units: one with all of the high voltage control, one with all the sensing & measurement. The sensing and measurement part will have its own case, incorporating: 8 inputs (7 thermometer/humidity & 1 for pH), selectable by pushbutton, 3 thermostats/humidistats (that share the same probes), and of course "reset" (trickier then it sounds).

And all the functions work ^_^

To Silver Buttons: I was thinking of that... you never know But the problem with getting a patent is that patents cost 10, 000$ so it's not really in the budget.

~Ryan

[Ryanstein]

I finished the prototype for the first part last night and it works!!

I'm now waiting on the circuit boards which I ordered on ebay, and once they arrive I'll start building a permanent version

Thanks for all of the support everyone

~Ryan

[Ryanstein]

Here's some pics!!!

As you can see... I kind of ran out of real estate on the first board and had to resort to a second


Close up of the power supply (with the considerably large gray heatsink... some parts get quite hot otherwise):


Close up of the thermostat section (the knobs for setting temperature/humidity are on the top right with the brass-coloured finish):


Here's a closeup of one of the temperature sensors:


My order finally arrived from Digi-Key (parts supplier)... behold the precision humidity sensor from Honeywell (they cost 17$ each ) Just to note: you may be thinking I could have just bought a digital reptile humidity meters for that much, but they are very cheaply constructed, can be off by as much as 15%, and tend to worsen over time, and take forever to respond to changes in humidity. These are practically bulletproof, are 3% accurate (and their accuracy will never change over time), and respond within about 10 seconds:


Everything works so far; all that's left in the meantime is to now add the humidity sensor to the circuit.

More updates to come!

~Ryan

[Ryanstein]

The only down side I would say to the system currently has, is that it cannot "recognize" the type of sensor being attached to it. As a result, each sensor must have circuitry to convert whatever measurement output a sensor gives, and convert it to something intelligible for the display. The next version (yes lol I already have ideas) will accept any sensor into any of the eight inputs, automatically convert the signals from different sensors, and shift the decimal point if need be. It will also have an extra thermostat/humidistat (four in total).

For now though, I'm waiting on the blank circuit boards I ordered. Once they arrive, I'll build what you see in the above pics ^^^ into a permanent enclosure.

~Ryan

[Guest]

You must be an EE (Electrical Engineering) major. I'm a novice hobbyist in that area and would love to see your schematic(s) and BOM (Bill of Materials).

Is it safe to assume that the pH sensor is for a pool of some sort? I have plans to add a fresh water pool into my tank, and your project would be perfect for me!

Also, a coworker has a large saltwater aquarium setup w/ a Novak (?) controller that can do exactly what you're building and probably more.

The Novak's cost is unknown to me, but I love building circuits, so your design is right up my alley! I would even name it after you. "Ryanstein" sounds like a good name for such a product.

*EDIT* There is a free PCB/schematic design app, called ExpressPCB. You draw out the schematic in one app, then link it to the PCB layout app. Once you're happy w/ the layout, you can order 3 printed, 2/4 layer boards for about $60 (given they're a "standard" size, about 2.5"x3.8").

[Ryanstein]

Nope I'm no EE major. I'm only 16 so not in university quite yet.

I may be able to send you one of the older revisions of a couple of the schematics (there are 5), since the final ones have yet to be drawn. However, I'll tell you the base idea for the circuit is that it operates as a voltmeter- and the different measurements are converted either to a 2-volt scale or a 20-volt scale, to be read on the display. The display chip is the ICL7107CPL from Intersil/Harris Semiconductor.

This controller will be used with a mangrove ecosystem (which is underway), where I will replicate the natural tides of the sea through a pulsed pump system. ~32 bit resolution lighting will simulate dawn until dusk through the overhead lights, and the humidity and temperature will be sensed, displayed, and corrected if need be. Since the project is still in the works, I may add other features, such as a water level adjuster to refill the tank as needed to compensate for evaporation.

And thanks for the link, I'll keep them in mind

~Ryan [/b]

[Ryanstein]

I'm still working on it... some more parts I ordered just came in, and I'll be building the final version quite soon.

Realistically, units like this exist already- Zoomed makes a temp/humidity controller for just under 100$ (though the humidity sensor's accuracy would be very questionable), and far more expansive systems for reefs can even support seasonal water chemistry and temperature changes, based on a pre-programmed calender... of course in the 400+ $ range.

The humidity sensor is the HIH-5030/5031-001 from Honeywell. The ~5031 has a built in dust filter, while the ~5030 does not. They cost between 10-18$ each depending on where you buy them from. Please note: they are only offered in SMD (surface mount) packaging, and as such have fairly tiny leads (see the previous page for a picture of one).

Good luck!

~Ryan

[Ryanstein]

It's very humbling to hear your encouragement...

Here's the cheapest I could find Zoomed's HygroTherm, as it's called (75$ US): http://www.reptiledirect.com/zoomedhygrotherm.aspx

In the end, the unit I'm building is far behind other reef units as far as programmable interfacing goes... the timers are more basic, have the option to be pulsed, lighting etc but since it isn't based on a microcontroller (programmable microchip), there are certain practical limitations to what my controller may achieve. Instead of using programming to add a feature, I must implement it with hardware. And that takes time.

Thanks for the encouragement!

~Ryan

[Guest]

If you do have any programming skills, you may be able to use Instructables.com's Arduino base project to program your timers and such. I would also suggest using relays (if you haven't done so) to trigger the 110/220V equipment, just to save your circuit from the initial current load of these devices powering up.

Actually, it looks like someone from Instructables has done this! Take a peek: http://www.instructables.com/id/Arduino ... _Humidity/.

BTW, my electronic skills are very limited to simply reading a schematic and building the circuit layout in my own way. I really don't have intensive knowledge of electronic components and how certain groups of components effect the overall circuit. Maybe I need to buy a book of some sort.

How did you about electrical circuits? Could you suggest a book for me to start with? Being only 16 and able to take this idea into different prototype stages is very impressive!

Not only that, but you've been on this board for 3+ years, which tells me that you've been caring for LHC's or other crab species since age 13. Again, I'm impressed with your own concept of responsibility and ability to care for such "fragile" animals.

When I was 16 , all I cared about was keeping my clunker cars running and getting girls. By no means am I assuming this is not another one of your hobbies, though.

Also, I'm still very interested in your final schematic once it is complete, only if you feel generous enough to share it with others.

Please keep up the excellent work and positive attitude, as the HCA and the entire LHC care-taking communities would highly benefit from your project! There are very few products specifically designed for hermit crabs on the market because of the general public's view of this species as a "throw-away" pet. Advocates like you and the HCA will only increase the public's awareness of the species.

[Ryanstein]

Again I'm really humbled by all of your comments

I got the 130-in-1 electronics lab by Maxitronix for my birthday from my parents when I was around 8 or 9... that's about when I started basic electronics, then into basic analogue and digital. So my basic knowledge of electronics came from that kit... but my working knowledge of circuit design and the many IC's came only from dedication to researching the internet, and experimentation. You could buy a breadboard, and some base components, but the above mentioned kit is a really good start. Even better for you may be the 200-in-1 though (less limited). I could PM you for more info.

I've researched the Arduino, and it really eliminates the hardware aspect- it's more about the programming. I personally prefer the hardware. Though there are programmable chips I could use, like PIC's, which require loads of both.

Don't worry, I don't mind sharing the main sensing schematic with you... (remember there is the whole high voltage section, too, and yes it has multiple high-current relays) but this is the rough draft (I haven't completed the final), and I've made numerous changes since then (3 thermostats/humidistats instead of 1, power supply redesigned, pH ranging fixed, and certain stability bugs).
THE SCHEMATIC: http://i113.photobucket.com/albums/n204 ... oard-1.jpg

This isn't specifically for hermits (it has way more features then needed- pH, for example), but I could eventually make a lower-end model for hermit crabbers.

Again thanks for the encouragement.

~Ryan

[Guest]

I have a 150-in-1 electronics lab, but my ADD kept me from reading the concepts. Instead, I only built the projects that I was interested in. The books are in my closet, so I guess I should get them back out. I also ordered the book, "Fundamentals of Electrical Circuits", from Amazon for $30 used, and hope to get it soon.

Most of my experience has been building homebrew guitar effects pedals and Ham radio programming cables from schematics, without ever really understanding the concepts.

Thanks for the schematic! It looks complex to me, but I've never tackled anything that intensive. The pH sensor would also be up my alley for the pool I want to build in my 'tat...

That's if they'll ever stop molting! I think I have 2 dug in now. One should be done within the next week or so, I hope, and the other just disappeared this week. That would be Mystique, one of my 2 smaller ones. So she shouldn't be under too long.

[Ryanstein]

Keep in mind the cost of a pH probe though- even the cheapest can be prohibitively expensive. And they do wear out. :roll:

That schematic will not work, though- like I said, there were many bugs, and even total additions and subtractions to the circuit itself. All that's left to do is stabilize the readout on the prototype on the previous pages- in thermostat setting mode, the display can flicker wildly. Once I work that out I'll begin redrawing the schematic.

The other thing I've learned from building analogue circuits blindly (of which well over half the circuit is analogue) is that so much can go wrong when one does not understand the circuit (and radio/RF still puzzles me). One capacitor in the wrong place and the whole circuit may malfunction...

Good luck with the molters.

~Ryan