An Ignorant Question On Pulse Detectors

[CladDog]

I have been researching this issue and cannot find a source to give a straight answer, so far as I can tell.

Maybe I am not asking the right question.

I know that pulse detectors that operate at a higher frequency are more sensitive to low conductors, and vice versa.

So is it correct to say that a detector that operates at 500 pulses per second is not as sensitive to low conductors as a detector that operates at 800 pulses per second?

 

[tvr]

have you read the information here?:
http://www.findmall.com/read.php?34,1777531

Click on the link in the first post and read it. There are two "pages" to it so click to the second "page" too. Read the comments in the thread too.
Hope the information in the link helps you with PI's and sensitivity to low conductors.

 

[CladDog]

Thanks for the link, but it mostly discusses depth, not sensitivity. The link on the first post no longer appears to connect to the article.

 

[tvr]

Here it is again, links to article at the nuggetshooter. Sensitivity to small gold is discussed in the article.

UnderstandingPI

 

[CladDog]

Weird. For some reason it will not come up for me.

 

[Jason in Enid]

So is it correct to say that a detector that operates at 500 pulses per second is not as sensitive to low conductors as a detector that operates at 800 pulses per second?

It's more complicated than that. Pulse rate, pulse duration and sampling period all play a part. You can adjust it to be hyper-sensitive to small gold, but you will have horrible depth and saltwater will drive it crazy. The more depth you want, the more you lose those tiny conductors.

This is why JW Fishers are great for deep water shipwreck hunting, but are far from ideal from beach hunting.

 

[Johnnyanglo]

A low conductor needs to be hit with more pulses to generate a voltage across the target. But the sampling time is dependent the circuit between coil and target. The time constant for eddy decay is fairly uniform, rather quick for low conductors (high resistance). But since small gold, thin rings, small jewelry, and such are low conductors the eddies don't last long. Most factory pulse detectors aren't going to have sampling time short enough to get the smallest gold - but a hand-built pulse certainly could. So, while an 800 pps detector sounds like it would be superior to a 500 pps detector, the physics of the thing is such that it isn't necessarily true. Consider that the available energy (battery) is finite, meaning more but weaker pulses vs. less but stronger, the greater illumination time is a benefit to get deeper eddies which reveal more of the target's character. On the other hand, shorten the sampling time too early and you get salt noise (beaches) and mineralized sand (magnetite), both undesirable (which is why factory detectors keep the user happy with a quiet detector - though less sensitive).

Sometimes, it is just best to read the reviews and hear the testimonials and complains by users - that is probably the best assessment of the detector's strengths and weaknesses.

Johnnyanglo