Small side project assistance appreciated

[Jeanius]

I'm working on an automated, programmable hydroponics system (legal guys, c'mon now ). I've been scouring the web for suppliers of small, cheap, rugged, virtually maintenance-free equipment, but all I've found has been lab-grade products ranging from $200-$1000, and for these purposes that just won't work. Although I'd like these to be digitally activated (i.e. through LabVIEW w/TTL logic), they don't have to have many bells/whistles. I'll go through the range of items I'm looking for, and if anyone has any suggestions I'd be forever indebted.

Peristaltic pumps (digital on/off)
Air pumps (digital on/off)
pH probes (without digital display, just simply an analog or digital output that can be read by a computer)
TDS probes (same ^)
Temperature probes (same ^)
CO2 probes (same ^)
Fluid control valves (digitally opened/closed)

I've already got a control scheme worked out (theoretically, that is), but I'm always open to other programming suggestions as I am definitely not a programmer. Thank you much!

[Jeanius]

No replies guys? Not even an "I don't know"? Could someone please tell me they acknowledged this and don't know how to help me?

[ash]

Ah.. acknowledged. And I don't know how to help you

However, I do believe you can use simple thermistors in conjuction with op-amps for the temperature probes. Just need to calibrate them properly.

[Jeanius]

Appreciate the reply. Yea, I thought about building a few of these myself, but I'm not sure that anything I build would be all that rugged and maintenance free. It'd be wonderful if a company/companies produced cheap probes and pumps, but I'm still having trouble finding them. If I do come across anything like that, be sure I'll post them here.

[ash]

If you are interested in just components, This might help:
RS Electronics - industrial electronic components distributor

Regarding the ready made probes and loggers.. have you tried requesting for samples? They usually entertain those requests Also, try checking surplus stores in your local area. Even junkyards can be a treasure place for the probes you seek.

Anyway, I believe analog components are pretty rugged, and do last longer than their IC counterparts. Since you do not require intensive digital processing and the like, you should pursue in building those sensors yourself!

[Jeanius]

Thank you for the link. It may end up being that I'll build a couple myself, but pH/TDS probes will probably be something I'd need manufactured by someone "in the know." Pumps... I'll have to keep looking.