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Eric, a question regarding the Aquapulse AQ1B


Hello Eric,

Would it be possible to add a SAT feature to the Aquapulse AQ1B. I find that the audio 'tick" drops into the silent zone all too easily from it's original position where it can be heard.
I guess it's a bit like the old Fisher Impulse where an extra hand can constantly tweak it. I find the detector loses sensitivity if the audio (SET AUDIO) drops too far into the quiet zone. A quiet signal won't raise the "tick" in order for it to be heard if the ticking is too slow or non-existent. I usually start with about a tick per second but it will quickly drop to a tick every 5 seconds and then ten seconds until it no longer ticks at all. This is solved by increasing the SET AUDIO (threshold) back to where it can be heard again......but the whole process then starts again.

I do have the 20µs version which is very impressive but I would put my grandmother on Ebay for a SAT feature.....:blink:

I did post this question on the Geotech forum with limited results.



Well-known member
Sounds like a circuit, part problem.
SAT addition would not really help in your situation.

Eric Foster

New member
Hi Tony,

I saw your question on the other forum and intended to answer, but here is the best place. The Aquapulse 1 was primarily for diving and at the time it was considered that SAT would be a disadvantage. On wreck sites you have to sweep slowly due to water resistance and also deeply buried objects can 'tune' out as you sweep over them. It is easy to put a simple SAT on the Aquapulse but that has the disavantage of a negative swing in signal when the coil has passed over the coil. Give me a few days and I will post some information on a better SAT circuit and where to put it on the AQ1 board. BTW there alway was a bit of negative drift which appeared to be due the the transmitter Mosfet warming up. This would be worse at 20uS than the original 30uS setting. These longer than normal delays are due to the sea water signal being much greater when you are on a wreck at 50ft water depth that just in the surf zone.




Thanks for the reply. Your term "negative drift" is a much better explanation of the threshold issue. I did speak with the folks at Aquascan about this and it is something that they are considering for future models so as you say it can be done.
I do know that I really need to be hearing a regular tick (per second) so that a smaller/deeper target can register as it readily interrupts that (regular) tick.

I am only doing beach and shallow water so am I correct in thinking that a SAT would be overall more advantageous for me?

Thanks again Eric,


Hello Sven,

The circuit is fine. New and tested from Aquascan so no problems there.
It is typical of this detector so I am hoping for a solution which should be a SAT feature.

It is a powerful machine and runs optimally when your left hand can tweak the SET AUDIO to keep the threshold audible at a nice tickover speed....about 1 click per second.