Metal detector using 555 timer circuit

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A very simple metal detector electronic project can be designed using a simple 555 timer integrated circuit . As you can see in the schematic circuit , this electronic project requires few external electronic parts .

This circuit detects metal and also magnets. When a magnet is brought close to the 10mH choke, the output frequency changes.
This metal detector project can be powered from a power supply that can provide an output DC voltage between 6 an 12 volt .
If a metal is closer to the L1 coil , will produce a change of output oscillation frequency, that will generate a sound in the 8 ohms speaker .

Metal detector schematic using 555 timer IC


what kind of choke is this and where can i get one from. this is important because i need it for my technology GCSE. please reply ASAP because i am already a little behind.

Is an 10mH air coil, something like this

dude it does'not effect a while .. only the mathematical lc calculation figure u can use the approx.

is it necessary to use a 10mH choke only?can lower inductances be used if low range detection is required?

can we use another inductor instead of 10uh and also can you give detail working of it

Yes you can use a coil with another value but after that you will need to check how audible is the signal.

what is actual frquency of ic555 which is changes after metal detection&how much distance within metal can detected by this ckt???

it continusly beeping with metal or without metal

Sound is generated anyway, but if an metal is detected, oscillation frequency will be changed.

In which mode ic 555 timer is working ?? Monostable or astable ??

This is working in astable mode.

hi, I assembled the circuit,em getting continuous sound without a metal..or with metal.know that it will sounds continuously,so frequency is not changing so can u fix my problem..

Check your coil (it should be air coil). If you made coil using feromagnetic core, remove it.

function of 555 timer in this circuit

I have connected the entire circuit . But then also when I bring any metal near it don't response. Any way tell me from where I have to apply ex-voltage from 1,8of ice or from the speaker joint.

Pin 4 and 8 of the 555 timer are connected together to VCC and pin 4 is GND. One coil terminal is connected directly to pin 3 of timer and speaker terminal.

pls post or mail the working of this ciruit and why the pin 7 is not connected ??

how many meters it can detect?

Hoe this work can any one explain it how its work

instead of using 8 ohm speaker we can use head phone

what output voltage waveform when the metal detect by sensor using ic555

but the speaker turns always on. It will be fine if the speaker turns off when there are no metal near inductor (coil) and the speaker Turns on when a metal brought near inductor . how can I do that? thanks

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