Check out the model radio control sites.

The Hanna meters work on less than 100ma so a very small regulator is all
that is needed. I have a pair of miniature switching regulators on my kite
photography rig. One puts out 150ma at 12V for the video down link and the
other 250ma at 5V for the R/C receiver from an 11.1V Li-Po battery. I think
I paid $30 for the pair and they weigh a total of 18 grams.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Hanz Schmidt" wrote in message
...
Where do you find a $20 buck/boost regulator??

Hanz

Geoff Schultz wrote:
"Glenn Ashmore" wrote in
:
For an R/O system you want something with a sensitivity to reliably
know when you get below 200 ppm. Hanna makes a series of TDS meters
that you can find at many aquarium supply sites. The HI9833318 is a
$185 high range panel mount meter. With an HI7634-00 probe remote
sensor it has a range from 1 to 2,000 ppm. You can set the relay to
trip at any level and it is sensitive enough for R/O purposes and it
comes in 120VAC or 12VDC. I think the probe is 3/4 NPT so you will
probably have to add an adapter to your product line.

When I was building my system I found the older 983319 in an aquarium
supply site. Talked to the Hanna engineers who recommended the 120V
model over the 12V model because voltage fluctuations could cause
reading errors. The 983318 is the new model and even if they haven't
figured out the voltage errors it would be a simple matter to put a
$20 buck/boost regulator on the supply line.

Since I put up a picture of my panel on the web site I have seen
several of the pro systems add the same model.

BTW, for a really nice looking panel check out
http://www.frontpanelexpress.com/. High quality reasonably priced
professional looking custom aluminum panels and free software to
design it with. Delivery in 2 weeks or less.


Glen,

Thanks for the info. I'll check out the Hanna series.

I had book-marked the Front Panel Express site quite a while ago
(probably from a posting from you) and have been using their software to
lay out the panel. I was quite amazed at the low cost. I just need to
fill in a few more components such as the TDS display. -- Geoff
www.GeoffSchultz.org