Inductive Proximity Sensor/ Metal Detector

It depends upon the metals that the thing is expected to detect. Iron and steel for example, being paramagnetic, will give a much better response than, oh, say vanadium, which isn't.

Ordinarily, I would imagine that detecting Iron and its alloys (Steel etc) would be easier due to the magnetic property - I assume that "Iron and alloys" detection is what people usually mean when they say metal detection. Is there a property of say Vanadium that can help us make a mechanism by which we can detect it?

Do you know anything about electronics? Are you an electronics hobyist?
If not I'd suggest you find a simpler project to start with, as anything with high frequencies can be a pig to set up without some decent test equipment. I'd suggest something at audio frquencies, in fact a simple audio oscillator is a good place to start, you can build your own test equipment starting with simple 555 based oscillators and maybe a nice Wein bridge audio oscillator.
Do you have access to an oscilloscope? Without a 'scope you are bet sticking to simple stuff.
Del

I have worked with simple circuits like monostable, astable configurations of 555. I can follow circuit connections, so I don't see why a simple metal detector would be too hard to make.

Absolutely love picking up little electronics projects to do with my spare time. Instructables is a great web site for just that. See this link. They use a relatively similar circuit to the one you provided.

As a starting point if you have limited or no experience, the Instructable is good.

The schematic you posted will probably not be any better and is complicated. BFOs are really usually not that good.

A better type for all metal searching is PI or Pulsed Induction types. I can send you pdfs for such types if you wish and if you give me a normal email address using the CR4 email for safety.

I personally prefer IB or Induction Balance as they can be designed to differentiate between magnetic and non magnetic metals if needed.....again I can send you pdfs for such types if you wish and if you give me a normal email address using the CR4 email for safety.

But both PI and IB designs are generally not for electronics beginners.......

Thanks a lot Andy. I will send you my e-mail on your message inbox in cr4.

5.6 IS BETTER, AS I inspect your schema, it looks good ,however the frequency has alot to be desired change that to 41819.2 in band width and you have a supior metal detechtor. ED MARTINEZ M.L.D. MOLECULAR LINEAR DYNAMICS.

Jay

if you really want to build a metal detector follow up with Andy. Your schematic has only one inductive coil. You really need two or more.

Better yet buy one. what you are going to spend to build a good metal detector is more than a good one cost to buy. I am all for electrical experiments but if this is your first in depth design build, you could choose better. You are not going to buy these inductors you will have to build them. Mass production reduces the manufacturers cost enough to make these cheaper than you and I can build them. Most of the manufacturers have been refining the design for several revs. Leading to much improved designs beyond your simple schematic. I have seen used ones on ebay cheap several times. Let us know what you decide to do.

You can also rent metal detectors from some rental places.

Andy I will be emailing you for a copy of the pdf's.

IS THIS TRUE?

http://www.youtube.com/watch?v=nyXQbcEnUzE

My friend tried this and says it didn't work. The calculator he used was a scientific calculator, though. Could anyone explain the principle as to how a calculator and AM, AM/FM radio can work together as a metal detector?