Metal Detector Design?

Thread Starter

MaxHeadRoom

Joined Jul 18, 2013
25,460
Anyone come across a decent DIY version for metal detector?
I am looking to put one together if I can find one.
There are a few designs out there, but it is nice to get feed back from someone who has had the experience.
 

ApacheKid

Joined Jan 12, 2015
718
Anyone come across a decent DIY version for metal detector?
I am looking to put one together if I can find one.
There are a few designs out there, but it is nice to get feed back from someone who has had the experience.
I don't know what the "state of the art" is these days for metal detectors, a friend of mine made one in the 70s when we were both studying electronics, this was from a magazine (possibly Practical Wireless) and it worked.

So if the technology has not changed much since then (that is the design principles are more or less the same) then you might find some of these older construction projects a good starting point...?

https://www.scribd.com/document/142113401/Sandbanks

This one - from ETI in 1977 - seems to have adopted a different principle to the typical home built designs:

https://www.yumpu.com/en/document/view/11524752/eti-549-metal-detector-geotech
 

KeithWalker

Joined Jul 10, 2017
2,399
I built an induction balance metal detector very similar to the one in the second URL that ApacheKid posted. It still works 14 years later I used an LM324 instead of transistors.. It is quite sensitive and very stable. On my first test with it, it detected foil from a cigarette packet a couple of inches below the ground.
 

Irving

Joined Jan 30, 2016
2,761
Gosh that takes me back! I was a spotty 16y old when I built something very like the ETI one (though not from ETI, Practical Electronics maybe?) around 1974/5. It didnt have the opamp but a pair of complementry PNP/NPN output transistors and the headset (ex-services) connected to the centre of a split supply based on 6 x C cells. IIRC it was built on tag-strips like the old valve equipment as veroboard was massively expensive and most of the parts came from Henry's Electronics in Tottenham Court Road (TCR was a great place for parts in those days, all gone now).
 

ApacheKid

Joined Jan 12, 2015
718
I built an induction balance metal detector very similar to the one in the second URL that ApacheKid posted. It still works 14 years later I used an LM324 instead of transistors.. It is quite sensitive and very stable. On my first test with it, it detected foil from a cigarette packet a couple of inches below the ground.
Man we must be almost the same age (I was born in 1959) and perhaps read the same magazines !

I'm originally from Liverpool and "Henry's" was always in those mags, we often wished we had a shop like that in Liverpool!
 

Thread Starter

MaxHeadRoom

Joined Jul 18, 2013
25,460
most of the parts came from Henry's Electronics in Tottenham Court Road (TCR was a great place for parts in those days, all gone now).
I may have bought there, did they do ship by mail?
I remember receiving a pro-forma invoice from a few!
This would have been in and around the '50's to 60's.
 

shortbus

Joined Sep 30, 2009
9,449
There's a guy that was active at ETO that has now passed, he has some supposedly good metal detector circuits on his site. The family is keeping it up, but they give a warning that it could come down at any time.
http://chemelec.com/Projects/Projects.htm Here are just a few of his many metal detector circuits -

http://chemelec.com/Projects/Metal-BFO-2/BFO-2.htm
http://chemelec.com/Projects/Metal-1a/New-Coils.htm
http://chemelec.com/Projects/Metal-2a/Ferrite-Coils.htm
http://chemelec.com/Projects/Reactance/Reactance.htm
 

Irving

Joined Jan 30, 2016
2,761
Yes, they did mail order too. Living only a few miles away, going into town on the tube (Underground/Metro/Subway) to wander up the TCR from TCR station to Goodge Street station, looking in all the army surplus outlets for all sorts of stuff was a great day out!

@ApacheKid - yep, we are... & probably did - PE & Wireless World mainly.
 

ApacheKid

Joined Jan 12, 2015
718
Yes, they did mail order too. Living only a few miles away, going into town on the tube (Underground/Metro/Subway) to wander up the TCR from TCR station to Goodge Street station, looking in all the army surplus outlets for all sorts of stuff was a great day out!

@ApacheKid - yep, we are... & probably did - PE & Wireless World mainly.
I moved to London around 1982/1983 and began to work in computing, I recall visiting Henry's and it was pretty interesting but even then I could sense the area was not as it once had been, the decline (if that's the right word) was already underway.

It must have been great in the 60s and 70s, when did that area begin to get electrical stores appearing anyway?

I wrote for ETI and Wireless World a couple of times, I visited the office in fact "IPC Magazines" to get photographs taken of stuff related to the article, this was around 1986, it was neat to see inside the offices of such a magazine, I wish I'd hung around longer, asked more questions.

I occasionally buy bunches of old Practical Wireless and stuff from eBay UK, getting it shipped to US isn't too bad and I consider the stuff great history, I love the older - 1940s/1950s issues, it's clear there was a lot going on, so many small active business all plodding away, did you ever watch this, great history from your neck of the woods

 
Last edited:

KeithWalker

Joined Jul 10, 2017
2,399
Man we must be almost the same age (I was born in 1959) and perhaps read the same magazines !

I'm originally from Liverpool and "Henry's" was always in those mags, we often wished we had a shop like that in Liverpool!
I am a little older than you, born 1938, but yes, I read Wireless World and Practical Wireless. I grew up in Lincolnshire but left home at 18 and lived in Weston Super Mare, Oxford, Reading and Melton Mowbray before I came to Canada in 1967. I shopped for electronic bits at the Edgeware Road market and ordered stuff from Henry's,
 

Thread Starter

MaxHeadRoom

Joined Jul 18, 2013
25,460
I am a little older than you, born 1938, but yes, I read Wireless World and Practical Wireless. I grew up in Lincolnshire but left home at 18 and lived in Weston Super Mare, Oxford, Reading and Melton Mowbray before I came to Canada in 1967.,
Me 1937 originally from Oxford and came here in '70.
A buddy of mine would go to different industries to pick-up/remove industrial waste, after he would visit the Atomic Energy Commission laboratory he would swing by my place and off load a bunch of goodies!
Meters, electronics all good stuff.! :)
P.S. Did my NS training in Lincoln, Royal Signals!
 

Ya’akov

Joined Jan 27, 2019
5,995
I can't reminisce about London, but I could probably wax nostalgic about the surplus and electronics shops district in Manhattan that were vanished to build the Twin Towers... if @Reloadron was here...
 

KeithWalker

Joined Jul 10, 2017
2,399
Me 1937 originally from Oxford and came here in '70.
A buddy of mine would go to different industries to pick-up/remove industrial waste, after he would visit the Atomic Energy Commission laboratory he would swing by my place and off load a bunch of goodies!
Meters, electronics all good stuff.! :)
You probably saw stuff I had thrown out. I was an electronic instrument service tech at Atomic Energy Harwell from 1960 to 1964.
 

MrChips

Joined Oct 2, 2009
26,470
I still have relations in Liverpool. I still have some copies of Practical Wireless. If you know roughly what year I can try to look it up.
 

Irving

Joined Jan 30, 2016
2,761
@ApacheKid I was quite obsessed as a kid, but not that bad, though I did build my first crystal set aged 7. I was only into valves for RF power stuff as a teenage Ham but was quite prolific with projects until the mid 80s when kids came along. At the time I was working for Plessey and then GEC Marconi as a electronics engineer on MoD contracts so had plenty to indulge me.

@MrChips Not sure if you were talking to me but I thought it was in Practical Electronics not PW though a quick look at the PE archives 73 - 76 doesn't show anything obvious. I'm pretty sure I had a subscription to PE and WW but I used to read all the mags in the newsagent and/or the local library and scribble down circuit ideas or persuade the librarian to photocopy articles so it could have been from one of a dozen or so publications. They were prolific at the time...
 

Dodgydave

Joined Jun 22, 2012
10,359
IMG_20220228_185131.jpg

Practical Wireless 1979 , pulse induction type

Mainly two types, Induction balanced, or BFO , IB is more sensitive than bfo and needs a Faraday screen on it to prevent parasitic capacitance.
 
Last edited:
Top