Fluidlever indicator

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TheSwede73

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Hi!

I need some assistance with a new project, just bought a campingtrailer and of course i want it to be filled with electronics
So i need a fluidlevel-indicator, just a simple one, showing the level with Led's.

Wires placed in the tanks, lighting up led's as the level rises or sinks, no fancy electronic sensors this time just the basic, as simple as possible..

I saw one somewhere just using transistors, resistors and led's i think, and when water shorts the wires its indicated by led's.

It should be pretty easy to make, but i need some guidande.

Thanks!!
 

hi.
There are a number of water level detectors on the web.
I Googled water level-indicator

Water-level Indicator - RED - Page95
 
Junk yards must be full of wrecks with fuel level sending units inside the fuel tanks. Marinas have them for boats. Hmm?
 
Thanks!

Yes, but i want to build it from scratch
I have found a couple of different solutions i will try

Thanks!
 
Don't use DC for sensing! (Electrolytic destruction) Sooner or later your circuit will be ready for the junkyard, too.

Boncuk
 
I've used this circuit before... You can add (pretty much) as many channels as you want, mine had 10. It uses a probe arrangement like the circuit Eric posted, but unlike that one, the circuit gives a bar graph display not a moving dot.
If you put an n.o. pushbutton switch in the +12v supply line, electrolytic action like Boncuk mentioned is minimized and battery current is only consumed when the button is pushed. Each led uses about 5mA when it's on but that would be if you ran it on 12 volts. I used a 9v battery, so the current was less. You can use any n-channel MOSFET that is the right size for the load, I used BSS123 in a SOT-3 package as the design was SMD. I would also recommend a suitable fuse in the supply line as well.

Jeff
 

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Thanks!

i just dont know what all the components in the picture are... im a total newbie with doing electronics without a ready made kit
Please decribe it as you would to a child..haha

Thanks again!
 
In each channel, there's two resistors, an LED and an N-channel MOSFET. The 2K res limits current thru the LED and the MOSFET. The 1M pulls the MOSFET gate to ground when no water is between the probe and probe common, keeping it turned off. When water is between the probe and probe common, the resistance of the water forms a voltage divider with the 1M. The water's resistance is (most likely) quite a bit lower than 1M, so the gate voltage goes high enough to turn the MOSFET on and current flows thru the LED.

Jeff
 
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1M = 1 megohm (1,000,000 ohm) resistor.

I've also used a single channel version of this circuit (with a larger FET) to act as a "overfull" monitor for a basement sump. It has already prevented my brother's basement from getting flooded due a malfunction of the float switch on the pump. Ten bucks well spent.

Jeff
 
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Hi again!

I have these transistors, will any of them work?
BC547B
BC557B
BC337
BC327
BC517
BC516
BD139
BD140

Thanks!!
 
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