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CAT # MK-108 (7 Reviews) Write a Review

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Product Description
Velleman# MK108.
Buzzer sounds when water is detected. Water sensor can be placed at a distance by cutting the board and using wires to connect the sensor. 9V operation. Battery not included.

Note: Kits cannot be returned or exchanged once assembly has begun.
WARNING: May cause cancer or reproductive harm.
California Prop. 65
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Customer Reviews (7 Reviews)

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Works great!

Reviewer: from Chicago

I have this near my basement sump. I even used a 9V transformer to power this up so I never have to worry about the battery. This unit is very sensitive.

282 of 534 people found this review helpful. Do you? Yes No

Water Sensor

Reviewer: from Orinda, CA US

This kit is easy to build, work wells, and can be used to trigger a relay instead of sounding the buzzer. Kit includes an on-board water probe, but circuit is so sensitive that you can just use two wires, with skinned ends for a probe.

2 of 2 people found this review helpful. Do you? Yes No


Reviewer: from Chicago, IL USA

I haven't built this kit, but have built similar projects. To convert the kit to run on 12 volts, you can use a voltage regulator. Or: Insert four silicon 1N4148 diodes in series between the battery and the circuit. Forward bias the diodes. (All diode anodes must point the same way, toward the battery. If you get the diodes wrong, the circuit won't work, but no damage will result.) Each diode drops 0.7 volt. If you want to skip the diodes: The Darlington has a 30-volt rating which should be fine. The piezo has a 15-volt rating, which is too close to 12 volts for comfort. All Electronics stocks a piezo and an electromechanical buzzer that have higher peak voltage ratings. You could substitute one of these. *CAUTION*: If you use the electromechanical buzzer, wire a reverse-biased 1N4003 diode across the buzzer. Otherwise, the buzzer's spike will kill the transistor. For 12-volt operation, one bias resistor *might* require a change. You might have to increase the top bias resistor value by 30 percent or more. (I doubt that the change is necessary.) If you need the change, I recommend going from 10K to 15K.

2 of 2 people found this review helpful. Do you? Yes No

Great kit!!

Reviewer: from Sioux Falls, SD

I picked up three of these kits. I was amazed at how easily they go together. Each kit consists of a PCB board, two resistors, a transistor, a buzzer, and a battery holder.

Used in conjunction with All Electronic's 108dB piezo alarm I can hear this thing two floors up.

2 of 2 people found this review helpful. Do you? Yes No

Pump Engine Shutoff

Reviewer: from USA

I work for a Lawn Care Co. We have main tanks which hold up to 500 gals. and 30 gal. saddle tanks. It has happened in the past when switching from main to saddle and back again that the valves would be left in the main to saddle position when they should be in the main to main position. A person would be spraying the lawn not realizing their error and then the saddle tank would overfill and you can guess the rest... I'm trying to modify the kit so the it will operate off of a 12v car battery and shut the pump engine off when the saddle tank overfills. I've got everything work out ok but I'm still having a little trouble stepping down the 12v to 9v without frying the transistor. Any suggestions?

1 of 1 people found this review helpful. Do you? Yes No
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