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Silent Masking / Overload With Tarsacci MDT 8000


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Many of you will never encounter this. As far as I know, there is no overload indication with the Tarsacci. I have observed that with intense magnetite black sands, you need to use caution about running the sensitivity too high, especially with Black Sand off, as I tend to run. I assume that cuts back on the transmit voltage to help prevent what I am going to describe.

If you bury a nickel in a true black sand beach (looking at you kiwis) or my hot beach up at Tahoe where I did this test, you can  get the machine tuned up for conditions. However, if you get it cranked up too high, all the sudden you will lose the nickel. It just goes away as the machine hits overload, but so far as I know the machine has no way to tell you this happened. It seems to be working fine.

Where this could bite you is tuning up on bad but not extreme ground, and then detecting your way into some intense black sand. You may go into overload without knowing it. This is not a freak out thing for most people to even worry about, but something I wanted to bring up.

First, I do not read everything ever posted about the MDT. Has anyone else observed this? Is there an overload indicator I am missing? If not, maybe something for Dimitar to add later. Its a common feature on gold prospecting machines, like the White's GMT for a good example.

"The GMT's circuitry broke a lot of new ground. It uses a reactive impedance transformation network to boost transmitter voltage for higher sensitivity. It uses an active transmitter regulator to keep transmitter voltage constant even when the search coil is moved over black sand that would blow an unregulated machine off the air." What this means is many detectors can actually go completely non-functional when operated over extremely mineralized ground and the operator will not even be aware of it. The GMT is very resistant to this occurring, but if it does the detector will give a loud audio "squawk" and the meter will read "BAD GROUND REDUCE GAIN".

The GMT literally tells you your gain is set too high for the ground condition. Set the control lower until this message goes away for optimum performance. If I've not overlooked it, this would be a good addition for people on the worst beaches.

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  • The title was changed to Silent Masking / Overload With Tarsacci MDT 8000

Steve what were your other settings if you remember? and were you using tracking ground balance? On thing I've learned about the Tarsacci is it's usually better to have it run stable than push it. At the point the machine becomes bubbly (hard to explain) it's time to back off either the Threshold or sensitivity. I personally like to decrease sensitivity down first because reducing threshold takes away from the target (Ability to hear deep targets). Yes black sand seems to reduce the transmission voltage as every time I've used it On vs OFF when comparing signals from targets, On always sounds worse. Another thing is I always salt balance even if it doesn't make sense for the area you are using it. Salt balance coupled with ground balance can be used to manipulate the Tarsacci to do some cool stuff. A discussion for some other time.

But to answer your question no I have not had my Tarsacci audio completely shut down. I have had it blank out momentarily but I always thought that was my wireless headphones losing connection and maybe it was. 

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1 hour ago, Steve Herschbach said:

Many of you will never encounter this. As far as i know, there is no overload indication with the Tarsacci. I have observed that with intense magnetite black sands you need to use caution about running the sensitivity too high, especially with Black Sand off, as I tend to run. I assume that cuts back on the transmit voltage to help prevent what I am going to describe.

If you bury a nickel in a true black sand beach (looking at you kiwis) or my hot beach up at Tahoe where I did this test, you can  get the machine tuned up for conditions. However, if you get it cranked up too high, all the sudden you will lose the nickel. It just goes away as the machine hits overload, but so far as I know the machine has no way to tell you this happened. It seems to be working fine.

Where this could bite you is tuning up on bad but not extreme ground, and then detecting your way into some intense black sand. You may go into overload without knowing it. This is not a freak out thing for most people to even worry about, but something I wanted to bring up.

First, I do not read everything ever posted about the MDT. Has anyone else observed this? Is there an overload indicator I am missing? If not, maybe something for Dimitar to add later. Its a common feature on gold prospecting machines, like the White's GMT for a good example.

"The GMT's circuitry broke a lot of new ground. It uses a reactive impedance transformation network to boost transmitter voltage for higher sensitivity. It uses an active transmitter regulator to keep transmitter voltage constant even when the search coil is moved over black sand that would blow an unregulated machine off the air." What this means is many detectors can actually go completely non-functional when operated over extremely mineralized ground and the operator will not even be aware of it. The GMT is very resistant to this occurring, but if it does the detector will give a loud audio "squawk" and the meter will read "BAD GROUND REDUCE GAIN".

The GMT literally tells you your gain is set too high for the ground condition. Set the control lower until this message goes away for optimum performance. If I've not overlooked it, this would be a good addition for people on the worst beaches.

Steve, I cannot comment on the black sand as I do not have any around here. However, if the Tarsacci does overload you will see a big OVL on the screen, and your audio will cut out. Nice write up.

Aaron

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Great, I guess I missed that OVL thing in the manual, and I do not watch screens. If you are running with no threshold there is no audio to cut out though, so be aware. The machine seems normal, but it stops detecting. And I guess he screen says OVL :laugh:

But thanks Aaron, that's why I brought it up, to learn!

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1 hour ago, abenson said:

Steve what were your other settings if you remember? and were you using tracking ground balance? On thing I've learned about the Tarsacci is it's usually better to have it run stable than push it. At the point the machine becomes bubbly (hard to explain) it's time to back off either the Threshold or sensitivity. I personally like to decrease sensitivity down first because reducing threshold takes away from the target (Ability to hear deep targets). Yes black sand seems to reduce the transmission voltage as every time I've used it On vs OFF when comparing signals from targets, On always sounds worse. Another thing is I always salt balance even if it doesn't make sense for the area you are using it. Salt balance coupled with ground balance can be used to manipulate the Tarsacci to do some cool stuff. A discussion for some other time.

But to answer your question no I have not had my Tarsacci audio completely shut down. I have had it blank out momentarily but I always thought that was my wireless headphones losing connection and maybe it was. 

I never use tracking as a rule though this would be a good reason to. I of course had my settings "too high" :laugh: It's been months so I'm not sure off the top of my head, but it was sparky!

This is not a big deal, and I'm not having a go at a machine I am keeping. Just bringing up a very obscure thing to be aware of, and one I'll be more careful to get tuned up properly for in select and thankfully rare areas.

I sold my Impulse AQ and still have my MDT. The two actions are not directly connected, but it is where I am at right now. :smile:

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1 hour ago, abenson said:

Steve what were your other settings if you remember? and were you using tracking ground balance? On thing I've learned about the Tarsacci is it's usually better to have it run stable than push it. At the point the machine becomes bubbly (hard to explain) it's time to back off either the Threshold or sensitivity. I personally like to decrease sensitivity down first because reducing threshold takes away from the target (Ability to hear deep targets). Yes black sand seems to reduce the transmission voltage as every time I've used it On vs OFF when comparing signals from targets, On always sounds worse. Another thing is I always salt balance even if it doesn't make sense for the area you are using it. Salt balance coupled with ground balance can be used to manipulate the Tarsacci to do some cool stuff. A discussion for some other time.

But to answer your question no I have not had my Tarsacci audio completely shut down. I have had it blank out momentarily but I always thought that was my wireless headphones losing connection and maybe it was. 

Abensen, 

One of the reasons your Tarsacci is cutting out is due lack of pressure via the battery cap spring to the battery. To resolve this issue, simply remove the spring and metal backing disc and put a #6 washer behind the disc and refasten. This should resolve your “blanking” issues. If not check your battery connector strip. Take some steel wool and polish off any corrosion ect that may have formed. For more information check out my Tarsacci maintenance video......

Aaron

 

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6 hours ago, Steve Herschbach said:

you need to use caution about running the sensitivity too high, especially with Black Sand off, as I tend to run. I assume that cuts back on the transmit voltage to help prevent what I am going to describe.

 

5 hours ago, abenson said:

On thing I've learned about the Tarsacci is it's usually better to have it run stable than push it. At the point the machine becomes bubbly (hard to explain)

When I first turned the machine on in the Condo, saw the OVL on the screen [figured out what it was] 

While I only have two days on the machine, I agree.  There were several times where the electronics got real chatty. I was running blk sand on, tracking off. 

The condition showed most when a wave was completing it's cycle and washing past me back to the ocean. It appeared to me [at times] the machine just "had enough" enough black sand washing by, enough water rushing, and was making it unstable.  Not all the time, but it happened a few times. 

The fix: Keeping it still for a bit/ and or slowly working up the beach away from repeated wave wash. 

Even though there was not an audio blackout, I could tell there was a loss of detector performance.

Regularly I swing my scoop handle at the coil. If you do this at times when a machine is running clean as opposed to chatty/bubbly/dirty, one will understand the reduced capability of the machine when it is not performing well. EMI has the same type of effect!     A machine experiencing even a light EMI pulse will not be working to it's highest potential.

You can get this same scenario on the Equinox as well. Without the overload symbol coming on. 

Dave

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Dave,

Try adjusting the Salinity during one of those “salt washes”, the coil just hovering over the water. You can do this while swinging the coil in short swings. Refer to my video on GB & SALT balancing.....

 

Aaron

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58 minutes ago, Aaron said:

Dave,

Try adjusting the Salinity during one of those “salt washes”, the coil just hovering over the water. You can do this while swinging the coil in short swings. Refer to my video on GB & SALT balancing.....

 

Aaron

Ya, watched your vid like 10 times already.  You do not understand the issue. At any time the waters edge can be 15 feet away to the ocean and 50 feet past me in 20-40 seconds time. Nothing to SB [just the way it is] 

Yes, there is lots of tonnage of moving water here!  

And yes, like I told Dew. The machine really likes to be out of the wash or in the wash. 

As long as there is 6" or so of water over the coil zero issues regardless if the water is moving [from my limited experience] 

I don't want the readers to think this is some sort of game changer, rather an issue of concern/caution.  

One thing I will be a bit critical of is the coil mount location. Lousy, to put it mildly. It is way too easy to tip the coil or have the force of the water tip it for you.  The MDT does not take kindly to being tipped, and will sound off when it is in the water [every time]  If I had the ear of the designer, this change would be job #1. 

Dave 

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  • 1 month later...

Aaron  

 Does the Tarsacci have a preset program that you can turn on and go?

 You were talking about the O-rings that it would be good to carry extra set. I’m wondering if the Tarsacci comes with that extra set are is it something that can be purchased locally ?

 I’d ask another question about if you ship free on another post but no reply.

 Chuck 

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