WATER EMPTY ALARM + Astable Multivibrator

About: Aircraft electrical equipment repairer.

I added the Astable Multivibrator to make the circuit have a beeping alarm. Try different resistor and Capacitor sizes to change the beeping interval. Currently it has a slow delayed beep. I tried deleting the intro picture to no avail. I made a change in the schematic to the Pot. Look out for that. I got the diffuser from Walmart and changed it by holding a lighter underneath the metal container that had a glued on glass container that came free when I heated it up.


Supplies are listed in my previous instructable "WATER EMPTY ALARM" and on the schematic.

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Step 1: Assemble

Assemble all the parts onto the breadboard according to the schematic. Put all the parts to the left side of the breadboard(except for the switch and battery leads) to make room for the 9v battery to be placed on the breadboard.

Step 2: Test

Test out the circuit by dipping the leads in and out of water while adjusting the Potentiometer. You my hear it give off a couple of beeps when placed in the water, that's because the capacitors are discharging. I have added a "quick and easy switch" made out of a wire and spring from a pen and put it next to the SPDT switch.(not shown in pic).

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