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help needed regarding "travel touch alarm"

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mrintech

New Member
friends,

i need your urgent help

i am preparing a project on "Travel touch alarm" whose ckt. diagram is given below:

**broken link removed**

the main problem is that i am not getting "500 primary / 8 secondary ourput tranformer" in the market....

so as per ckt diagram pls suggest any alternate solution

or

simply suggest any replacement

- with best wishes and please reply soon
 
I do not see how your circuit works:
1) The touch plate is connected to the +9V supply, so the 555 will not be triggered.
2) The output high voltage of the 555 is 7.7V. The output high voltage of the unijunction transistor is about 7.0V. So the power into the transformer is only 25mW and the speaker's power will be a little less so it might not be heard.

Fix the 555 circuit so it can be triggered. If a touch plate is connected to pin 2 and another touch olate is connected to 0V then the 555 might be triggered if you touch both plates with damp hands.

The transformer reduces the power to the speaker. Use a little power amplifier like an LM386 to drive the speaker.
 
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