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Is this Possible (two receivers?)

A

Anonymous

Guest
Eric: I am a novice when it comes to PI detector theory. However, it seems that pulse delay is the biggest factor in detection of gold vs coins. I would assume that pulse delay is a receiver function. If this is so, could dual receivers be mounted with two different delays and dual audio freqs so that one rcvr would be sharp for gold rings etc., and the other rcvr would be capable of picking up the silver/clad coins?
 
Hi Dale,
Pulse delay is the time from the switch off of each individual transmitter pulse to the start of the receiver sampling time. The shorter you make this, the more responsive the detector becomes to smaller and less conductive objects. The tradeoffs are that the coil becomes more critical in its construction and you reach a point where the false alarm rate goes up due to signals from ground and beach mineralisation. A delay of between 10 and 15 microseconds is about as short as you can go for most treasure hunting applications. Pulse induction is a very flexible technology and you can have as many receive channels as you want, each operating at a different delay. In practice, there is little benefit in using more than seven or eight. Even with two channels you could get a reliable indication of whether the object was small,large, good conductor, or poor.
Eric.
 
Thanx for a very fast response. I am a retired electronics tech so I can follow what you say. Why if this would improve ID, is it NOT done? Or, am I just not aware of the detectors that use this concept? In any case, I think two or more rcvrs would be a help on the beach, where the clad coins at least pay for the batteries while looking for the gold!
 
Eric... How does water depth affect sensitivity? In other words, if a PI unit will detect a nickle at 15" in the surf, will it detect at the same depth in 50' of water? Also, did you design the circuit for the HeadHunter PI?
 
Hey Jeff (Jeff here too),
That's a nice website you have there...
There's differences in detectors for beach use versus those for scuba. I think the Fisher Impulse is more designed for diving use than beach use, and apparently some of Eric's other machines are built more for scuba than beach hunting, although I can't remember the names of them off the top of my head.
 
Hi Jeff,
Water depth does limit the amount of sensitivity you can use with a PI detector. You can search with a sensitivity that enables you to pick up a nickel at 15in in 1
 
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