Water Activated Monostable Switch

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tom08

New Member

• Nov 28, 2009

• #1

hi all
For my GCSE Electronics project i am planning on making a duck that, when placed on water, flashes a series of lights and quacks for a set period of time. My plan is to use monostable>astable>decade counter. Ive seen a few monostable 555 touch circuits but i dont know how to get it to be activated by water. what do you suggest? thanks

 

crutschow

Well-Known Member

Most Helpful Member

• Nov 28, 2009

• #2

Use a CMOS gate with a high resistance to ground (say 10MΩ). Then connect the gate to one electrode that contacts the water. Connect another electrode that contacts the water to the plus supply. When the contacts are in the water they should conduct enough current to raise the voltage on the gate to a logical one and turn the gate on.

 

transistor495

Member

Forum Supporter

• Nov 28, 2009

• #3

Good project

..or you may use this kind of activation connected to a delay timer + led flasher + how you're making the quack sound?

 

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T

tom08

New Member

• Nov 29, 2009

• #4

The quacking sound will be produced via a voice module. thanks for the ideas ill check both out.

 

transistor495

Member

Forum Supporter

• Nov 29, 2009

• #5

Well, this monostable section can be followed by the water activated switch described above(but with minor modifications regarding the power supply condition), T1 will be swiched ON for a particular time period as set by the pot, so by attaching the light flasher circuit with quacker you get the electronic duck in operation.

PS: You may try alternative methods

 

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T

tom08

New Member

• Nov 29, 2009

• #6

how about i just do a normal 555 monostable timing circuit with a liquid sensor where the switch is. here's a liquid sensor link : **broken link removed**

 

K

KMoffett

Well-Known Member

• Nov 29, 2009

• #7

Just bench tested this. Water sensor and monostable in one. No need for a special sensor...just two wires.

Ken

 

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Last edited: Nov 29, 2009

transistor495

Member

Forum Supporter

• Nov 30, 2009

• #8

Hello tom08,
The solution suggested by Ken is an alternative way of doing it