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ericgibbs said:hi,
It really depends upon the resistance of the water.
A number of members have posted water resistance values, the values seem to vary quiet a lot.
It would be very easy to wire up a test circuit to check the resistance.
With no water path between the probes, the current leakage will be VERY small, minute battery drain.
Why have you put the ON/Off switch in that point of the circuit and not in the battery lead.
If the resistance of the water is high, then consider using a FET rather than a transistor.
joecool85 said:Alright...well, I put the circuit together and it seemed to work when testing with a LED. The LED was off, then when I dipped the probes in water it was nice and bright. Well, I bought a buzzer, and it buzzes when the probes are out of water. I tested with the LED again and it worked fine. Come to find out, it is giving 0.523v when the probes are out of water! How can I fix this? I've tried swapping out the resistor all the way up to 10meg ohms and all the way down to 1 ohm with no luck. Am I missing something here?
Rolf said:Did you indeed use a piezoelectric buzzer?
Or your buzzer have a coil and did you put a clamping diode across it?
You might blown your transistor!
joecool85 said:I used this piezo buzzer from radio shack https://www.radioshack.com/product/...r=1&origkw=buzzer&kw=buzzer&parentPage=search
philba said:Your transistor is likely blown or incorrectly wired. 10K from base to ground should turn the transistor off.
this is a very general application, any NPN would be fine.