Double beep coin

[earthmansurfer]

Interesting and funny thing happened today. Hitting the little playground (in Germany)and trying to pick up missed coins. Slowly realizing the coins here hit all over the place on the ID. I got a solid 79/81 double beep hit and ended up digging two holes withing 2 inches of eachother. Both still giving a signal but both being empty! I probed between the two and found a 1921 Zinc coin (ok condition but faded out). I thought it might have been on edge but even out of the ground it gave a double beep. I had to raise the coil 6" or so to get a single beep and the id was a solid 79 then.

Also found a very small 1935 Deutsches Reich. It is smaller than a dime and hit very solid at around 4" or 5". ID'd at around 64 or so. Coin is bronze though. Rained the last few days so that's probably the reason for the harder hit. I had almost dug that coin on 2 different occasions but kids were near and I thought to come back to it at a later time... finally remembered.

Wonder if the zinc composition of that first coin had something to do with the odd hit??? Running out of coins in this playground, need to find another one...

Feeling comfortable with the T2 after one month or so. Need to take my Nautilus IIB there and see how it operates. I think I'm missing the rusted iron/zinc coins from there as they probably hit like iron, but I can pick them out with the IIB. It's all good as I don't miss them!

In some tough ground I notice the detector gets noisy if I put the discrimination above 40... anyone else? Why would it do that? Ran the Sensitivity at 60 to 80 mostly.

I think I've pulled about 15 coins from this little playground, dated from 1921 (today's was my oldest from there) to 1941, with all but 3 from the 20's! Really odd???

Take care all,
Earthmansurfer

 

[Bill W.]

Shallow coins will give hit on the outside of a dd coil more easily than other coils. That might have been what you were experiencing.

-Bill

 

[Eddie Currents]

I get double beeps on shallow coins too. It's the coil.

EC

 

[Mike Hillis]

Hi Eman,

I've noticed the same thing in some places. Only thing I've been able to link it to is rusty iron spiking. In those areas when the disc is at 40, you get the spikes, but when you have the disc turned down to around 25ish or so, then the spikes are associated with the low tone and you don't hear them.

HH

Mike

 

[Cody]

A double beep is caused by the recovery speed of the electronics in the receiver. We most often see them on shallow or an elongated target such as a nail. If the electronics recover while the coil is still passing over a target we get a second positive hit. A nail has eddy current flow along and around the axis of the nail so we get a hit on each end of the nail something like a "hot spot" on each end. Of course we don't need for the elongated piece of metal to be a nail but metal in that physical shape. Depending on the settings of the detector shallow coins will almost alwasy produce a double beep on some detectors.

 

[earthmansurfer]

Hello Cody,

Nice to see you back. Hope all is well with you. Great post and I miss reading your informative posts. I'm really into understanding the science of detecting...(unfortunately sometimes I enjoy it more than detecting... but that's what winter is for.)

I'm wondering if there is a way to swing this detector slow considering it's design. So far, I like using the db (for slow checking) mode but have swung it slow in 3b also with some luck. I guess since the db mode uses continuous sampling it makes sense.

Have you played much with the T2? What are your thoughts. Would love to see a summary review from you.

Thanks,
Earthmansurfer Albert

 

[Cody]

I am definitely interested in a T2 but have not purchased one. For the most part I don't post on a forum unless I actually use the featured detector. Once in a while there is something that is common to all machines I have used so will say something. The design engineer for the T2 has a heck of a reputation and has put together some great machines so I am always interested in what he does. I am just about ready to get one and give it a go.

Unless there is an adjustment for recovery there is going to be a best sweep speed, depending on soil minerals, for an optimum signal for targets. I don't know how slow you are able to sweep the coil, my guess is you like to crawl over the ground looking for those really deep hits, but most detector don't have an adjustment to help you speed up or slow down recovery. The design engineer prefers to have a set sweep speed and require the user to adjust to the optimum sweep speed. That is part of what gives the T2 such a nice quick response that I am reading about.