Mains detector

This device detects mains and has tested more reliable than commercial models.

NOTE:If this device fails and you are hurt, i will take no responsibility. Test the device before use.

That said, this is what you need:

1)5 npn transistors
2)wire
3)9v & clip
4)speaker
5)switch

Step 1 Wire the circuit

The circuit is simple.
Wire up using the picture below.

Comments

[lemonie]

Do you really need 5 transistors? What's your aerial design - I'm thinking that a loop might be good?

L

[scratchr]

Yes, unless you have a transistor with 5 times the gain of the 3904.

[lemonie]

So it doesn't work with only 4?
What is your aerial like?

L

[scratchr]

The sound is already hard to hear with 5.
You could try 4 with headphones.

[lemonie]

3rd time - what is your aerial like? Might you get more signal by redesigning it?

L

[scratchr]

It is a simple wire on v1 on v2 it is a bar.
I tried a coil on my first version.
The closer and more surface area the better.

[lemonie]

The coil wasn't better? I'm thinking of building one, which is why I'm asking.

L

[scratchr]

The coil did not seem to improve the device.
I used a coil with 4 inches of turns around a 1cm inch stick.

[lemonie]

OK thanks for trying that, if I do make one that works, I'll let you know.

L

[beehard44]

what if i use darlington pairs? i think i can use 3 darlington transistors and get the same output

[lemonie]

Try it and see, it's often the best way to find out.

L