• Forum server maintanace Friday night.(around 7PM Centeral time)
    Website will be off line for a short while.

    You may need to log out, log back in after we're back online.

making a pinpointer out of an old detector

mikie2084

Full Member
Joined
Oct 31, 2009
Messages
138
Location
Virginia
I have an old Micronta 4001 is there anyway to take it apart and make a good pinpointer with it?

Thanks

Mike
 
Hello mikie2084,

Yes, I think you can but it may take some experimenting. A typical MD sends a pulse at a frequency, then receives it on a seperate coil of wire. The system measures changes in the inductance between the two fields.

The system expects there to be a known resistance and inductance on the loops. If these are so far out of spec on the windings of your home made pointer wand, then the circuit might not work well at all.

If we can know the specs from a schamatic on the frequency the detector uses and the resistance of the coils of wire, then the12volt com would have the tools and folks to help you finish the equation and determine the size of the new wand bobbins and how many windings etc.
 
I honestly dont know any specs on this detector! i got it when i was a kid, and tried to see how pinpointers worke but im far from an electronics expert! except for cars!
 
Simple mod?

Being a VLF (and possibly a BFO) detector you have two resonant circuits; the transmitting circuit and the receiving circuit. Each has a separate coil and they're shielded from each other to avoid interference. The transmitting coil (outer coil) creates an RF field that penetrates the ground and the receiving coil (inner coil) then recieves any reflected RF. Any phase shift in the returning signal is then "decoded" by the receiving circuit. In the case of a BFO (beat frequency oscillator) system the resultant change in shift is in a varying audio range; the greater the shift the higher the audio frequency.

To make any change to the coil assembly you'd have to determine which you have; VLF or BFO. You'd then have to determine the frequency it operates on and wind coils of proper inductance to assure resonance. Improper inductance could possibly damage the transmitting circuit with overcurrent.

If you don't mind using the same coil you can create a "pinpointer" by just reducing the RF field being emitted by the transmitting coil. The simplest way to do this would be to install a potentiometer in series with the transmitting coil lead to reduce current flow but not affecting the resonance of the tuned circuit. Reduced current equals reduced field strength equals reduced ground penetration depth. Then again, maybe the Micronta already has a "sensitivity" control that might accomplish the same thing?
 
Back
Top Bottom