Let's Make Robots!

TB-007 Metal Detector

TB-007 (ThunderBird 7) Big Brother of TB-6. (Blogged)

TB-007 is able to Detect Metal  (Coins, Rings, Gold, Electric Underground/Floor Cables and annoying Bottle Tops)

Improved Traction Design - aimed to cross over Stones and Sand.

I totally redesigned the Chassis of TB6 to make it more robust.

1st Video Shows it in Action. (-: towards the end are some Outakes :-)

2nd Video :- PolyMorph SkidSteer Helper ©



Here TB-007 has been fitted with a Wireless Camera -

so i can sit in my deck chair and watch its progress should it wander off.

The Camera is mounted to a servo which also has a Laser pointer attached (see main picture)  -

During "Fine Detect" phase of software loop, the servo positions itsself to look

and pinpoint with laser and Video the exact location of Metal Found.



The underside shows the layout of the Motors and a new PolyMorph SkidTurn Helper ©



Here is the  PolyMorph SkidTurn Helper © in more detail - In the Down Position.



 In the Up Position.

It is a hollow Poly-Morph "Thingy" which is connected to a servo - when activated it lifts the whole back end up into the air.

Then the front wheels can turn in opposite directions and the "Thingy" slides -

allowing TB-007 to turn effortlessly on the Spot - over the ground (polymorph is very smooth).



The BirdsNest (Thunder) ---- not so pretty but hey it works -

i have to install a second Voice Arduino so i have not finalised the layout

(-: velco straps are magic for rapid proto-typing :-)

TB-007 is Arduino Based with a Motor Shield (that controls the 2 main motors - 1 stepper motor and 3 Servos)



Here are TB-007s Test Coins -

The 5 Cent Silver American Indian coin known as the "Buffalo" is my Favorite.

The 500Lira (in video) and 10F (silver/bronze ringed) coins have the best detect signal.


The Metal Detect Electronics have be Hacked out of a Hand Held Metal Detector.


The Metal Detector consists of 2 separate detetor coils wound around a ferrite rod.

 The Circuit is a Beat Frequency Oscillator - able to detect metal and also live electrical cable.

  The Beat-frequency oscillator (BFO) is the simplest type of metal detector.

The basic beat-frequency metal detector employs two radio frequency oscillators which are tuned near the same frequency. The first is called the search oscillator and the other is called the reference oscillator.

The outputs of the two oscillators are fed into a mixer which produces a signal that contains the sum and difference frequency components. This signal is feed to a low-pass filter removing the harmonics. As long as the two oscillators are tuned to the same frequency, the output will have no signal.

When a metallic object disturbs the magnetic field of the search coil, the frequency of the search oscillator shifts slightly and the detector will produce a signal in the audio frequency range.




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OMG!!! I thought of something EXACTILY like this JUST TODAY!! btw we went metal detecting and got like $4.25 in change....
I am really new to this Metal Detection bug - since building TB007 i am even more inquisitive - and will be shortly buying a bigger handheld sweepy one so that i can join in the fun ......
All your designs are cool. Except for the Rats Nest :P

I prefer to call it "Rapid Prototyping" , well thats my excuse and i am sticking with it...........

.....thanks for the support....

Wow, awesome! Now you can go down the beach and monitor what TB7 is doing from your camp chair. Do you think you have room on the back of the new chassis to put a servo actuated wire scoop?
Im sure you know how to program it...but have it pull ahead...push down the scoop, open of course...close it..back up...and check to see if it got it.....

 Well one idea is using a Hairclip - clueless at the moment how to motivate the dash thing .............

..... Answer on a "Post card"welcome ......

I know that there is enough weight to allow TB007 to activate this under the "sand" a

few centermeters with the help of the  PolyMorphthingy 



Post card?

Maybe a cable setup would work with that, think bicycle brake cable. Drill a small hole through the middle of each handle for the cable to pass through. The sheath would be stopped by the handle, so when the cable is pulled it'll pull the other handle towards the sheath.

 Bicycles are just "Up My Street"  thanks for the "postcard" idea.



Cool ;) My feeble attempt to describe a cable's operation was completely unnecessary. Haha.

Wonder if a standard hobby servo has enough gumption to pull the spring in a hair clip?

This could be a new standard in DIY robot grippers! Good idea Gareth. I'm gonna use it someday.