Can anyone tell me what I have to change in the schematic on this page: http://www.aaroncake.net/circuits/lightdrk.htm to be able to use it with 12V instead of 9V? Thanks.

Rain

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The relay would change to a 12V device

 

I agree, but the circuit itself is extremely poor and very badly designed, it's not likely to work very well, and can easily be destroyed by adjusting the pot to one end!.

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... :lol: duh! A realy! I knew it was too simple. :P

Actually, what I'm looking for is something that will detect an object passing in front of it. But digging even farther, what I REALLY need is something that will detect water in a vertical pipe. I was thinking about using this and having something floating in the pipe to pass in front of the sensor at the top of the pipe, which will be dry. But anything will do as long as it activates a relay when it senses water. Float valves are too much money. And conductive sensors will rust too fast. Any suggestions guys? Thanks.

Rain

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When life gives you lemons... make a battery.

 

err, my first thought is you could work something out using lasers, which when shone through water, the light will be refracted, and so won't shine on a receiver, indicating that there is water present.

Any good?

 

What do you want to do? Measure flow, level, pressure? From your description, it seems like you want to measure flow...

You can install a plate/spoon type device on a hinge that will mechanically move as soon as water moves past it. Just detect the movement of the device. Here's another circuit to detect level:


http://www.uoguelph.ca/~antoon/circ/sensor1.htm

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Stef

 

Maybe you could use what I recently built into my boat to detect water level in a rather small compartment.
I had one of those magnetic door (inside frame) switches, as used for home alarms. The magnet part was nicely sealed in a little tubular thingie and I just drilled a suitable hole into a cork and glued the magnet in - it will stand up even to salt water in its plastic case.
The matching tubular reed switch part was fitted into a sliding PVC spacer that fit neatly inside the top of a short, vertical, 1" PVC plumbing tube section. There were holes drilled on the tube's bottom end to let water flow in and out freely.

As soon as the water level rises, the cork ( with magnet) floats up inside the PVC tube to trigger the sensor. The position of activation can be fine tuned by sliding the reed switch housing up and down.

As the reed switch only handles 1/2 Amp it switched a relay, to turn on a bilge pump for getting rid of the water.

Klaus

 

Hm, you know, I think I'll look in to that. That might just work for me. Thanks a lot.

Stef: Actually, I'm just messuring water level.

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