powerflash + photocell

[liderbug]

Setup:  A 4x4x2 tank of water.  A small brick of styrofoam supporting a length of 1/2" pvc pipe with 1/4" holes every inch sticking up out of the tank.  A LED nightlight on one side of the pipe and a CdS photocell (1/4") on the other attached to the terminals of a PSC01.   I've found that in mode B3 the terminals have ~1.1Vdc.  My cell has about 2k ohm when dark and about 300 ohms when lit with the LED.  As the level in the tank drops the holes pass the LED/PC and I get  notified.  And it seems to be working.  However my test rig on the bench says I have to lower the resistance to about 50 ohms to trip the module.  Thoughts?  Improvements?

Thanks

[Brian H]

Mostly curious.
Is the ~1.1 Volts open circuit with no load on it?
My older PSC01 units have closer to 6 volts on them; but X10 and X10Pro have been redesigning things over the last few years.

You do prefer to not have to use added electronics if possible?

[liderbug]

Aprox 1.07 vdc no load / open circuit (my RS $8.95 mm)(remember: B3).  A 2K pot gives me 195 mv and an Off condition ...  turn, turn, turn... 55 mv (880 ohm) = On.  Unturn, unturn... 125 mv(1800 ohm) = Off.  My CdS cell shows 25k dark and 450 ohms with the LED on it.  Hmmm, charting that says I should be good.  However any advice gladly taken.

[Brian H]

Thanks for the updated information and measurements.
It does sound like the Powerflash has also been revised from my older ones.
I wounder if that model will still work with an ELK930 Doorbell Sensor as it used the Powerflashes sensing voltage for power.

With the 880 Ohms turning it On and your photocell going to 450 Ohms. It sounds like you have a good margin for a reliable trigger.

[liderbug]

OK - time will tell.  Here's my setup: sump1 is the whole thing, sump/tank, pvc pipe, 2by, x10 & light covers.  #2: nightlight in center.  #3: gluing the panel edging to orig pipe allowed me to get the led within 1/4" of the cell. #4: Side on view.

09/16 13:01:02  rcvi addr unit      10 : hu P10 (Sump)
09/16 13:01:02  rcvi func              On : hc P
09/16 13:01:02  rcvi addr unit      10 : hu P10 (Sump)
09/16 13:01:02  rcvi func             Off : hc P

[Brian H]

Thank you for the added data and photos.
Keep us up to speed on how it works in the long run.

[liderbug]

Will do.  And to answer your previous question: ... use added electronics ...? Naw, KISS.  Besides - half the challenge.  And: Linux box (typ'n on it now), heyu, crontab, X10 outlets to run pumps (2), and exhaust fan, LaCrosse TX60 for the temp graph (which runs the exhaust).  And a pum01 in the mail for the heater.

See:  http://lidderdale.net/hydro

[dhouston]

Should you decide your setup needs improvement, a friend down in Florida has been posting recently in another forum about a series of experiments to measure the levels of the freshwater and wastewater tanks on his boat. Here's a link...

• http://www.zbasic.net/forum/viewtopic.php?t=1562

[liderbug]

Ain't geekdom great!   

[dave w]

Will do.  And to answer your previous question: ... use added electronics ...? Naw, KISS.  Besides - half the challenge. 

If needed, you could deviate slightly from KISS by adding a battery or wall wart in series with the CdS cell.  You would have to experiment to find proper voltage. I don't know if 1.5 volt would be enough to trigger the PF.

[luke03]

You could add a WebControl board, use its analog input to read the photocell output.
Then use its X10 RF command to control your X10 switch or modules.

[Brian H]

luke03;
That would probably work, but sounds awefull expensive and complicated. To do such a simple task.

[liderbug]

I ended up using a buck.98 micro switch with roller from RS.  Then every inch a 1/8" dia piece of wire under some tape.

----^----^----^----  only upright.  Working great.

[Brian H]

Simplicity at it best.