kazimahbub

thanks for share

cannibal

Hello

I didn't understand the part of contacts
how it will be and how it will work if the water touchs it ??!!!

audioguru

Water has some salts in it then it is conductive.
When water is between the contacts in the first circuit then it turns on the transistor that turns on the oscillator.

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Uncle $crooge

abu emran

Thanks For All

xl5

Can i insert a photocell in this cct to prevent it triggering when rain falls during the night when i am in bed and if so where in the cct should it be best placed without effecting the operation too much.

mudassir_semiconductor

i made a automatic dam door control system using 555 timer but after that ...... i tought 0f using microcontroller and i did it ..... insted of all this u can only do by switch which will activate on any conduction ....... r ugetting me ..... this circuit is only for the understanding of transisters

audioguru

I added an LDR (light dependent resistor) and a 100k resistor. When it is light then the LDR is a low resistance and the 555 operates normally. When it is dark then the LDR is a high resistance and the 100k resistor causes the 555 to be reset. Try different values for the 100k resistor.

This way, the battery is drained about 5ma when the sensor is wet in the dark. If the sensor is not wet then there is no drain.

Attached Images

water_activated_alarm.PNG (13.2 KB, 45 views)

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Uncle $crooge

xl5

Hi Audioguru, thanks for posting the cct diagram with ldr i will now try the cct out on my breadboard. My very first project was a rain alarm back in 1972 it worked fine but if it was not switched off before retiring for the night sometimes it doubled as an extremely early alarm clock

I have in the junk box many types of ldr's i will experiment with the resistor value.

umairtheonlyone

Hey can anyone tell me about the speaker part I couldnot find it in the parts list in ewb

audioguru

The 555 has a max allowed output current of 200mA so it might be damaged if it directly drove an 8 ohm speaker when it has a 9V supply. Use an 18 ohm speaker or connect a 10 ohm resistor in series with an 8 ohm speaker.

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Uncle $crooge

umairtheonlyone

I cannot find the speaker anywhere I mean LS1 is not in my parts list in electronic work bench

umairtheonlyone

I cannot find LS1 anywhere in electronics work bench parts list

Rachel49

can i change BC109C to BC107?? plz help me...

Nigel Goodwin

You could try, but a BC109 is a much higher gain device - so it depends how conductive the water is.

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PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

RAKS

Thanks for all.

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