pjrough

Many thanks,

I will keep this in mind.... For the moment I am waiting to reply from the dealer to reply...

Yah, right Kac, buy I am in Europe, so I have to go through my local dealer....

This one is CNC milled from solid acrylic block. My buddy is manufacturing it for me....

Yes, It sounds weird. 

But I'm 100% because I have tested the detector and noted gained results at each step. 

Will try to send it to the dealer, let's see what he'll say.

Don't want to swap the coil in this one due to the warranty and due to the fact that I'm not sure it is a coil problem. Dual field is a series connection of two size coils. If one is down, the other will not work neiher. ....but on the other hand, it could be a good explanation.

Not a good time for me to stay without water impulse machine, as the land machine waterproofing is on its long way to come ....

This one will be the detector to test out different coils (coils swap option).

Hi, there. I was using my TDI BH for almost two years now. It worked great till the las week then I noticed an important sensitivity drop.

In other words, the detector switches on and work as usual, but no matter what I do, I am getting less depth on my targets.

Just to give you some numbers. My test target is a nickel coin which I was detecting from 27 cm a least (10us, gain full, gb off). Now, under the same conditions I can detect the same coin at 10-12 cm only.

It is not the matter of the battery, as I have tested it with different batteries I have laying around.

The TDI have a couple if weeks warranty left, but I have some doubts about my dealer's possibilities. On top of that the type of the fail is rare. Looks like the detector work as it should if not the lower detecting depth. For the person who is not familiar with TDI BH, this type of defect could be not so obvious.

Any ideas what could be the reason?

Thanks.

6 hours ago, Skullgolddiver said:

plastic anticut sheath to cover the entire coil's cabl

You can use a heat shrink tube to protect the cable....

3 hours ago, Joe Beechnut OBN said:

....

Honest, I think fisher should check into the 26650 batteries..No difference in weight from the original battery pack...and unless they can come up with some super 18650's I don't think they can top the EML batteries...

Joe, there is a better option. Samsung got the same capacity in smaller battery size - 21700.

Using this batteries in different projects since time and absolutely happy with performance.

Thanks.

As to Detech - no I haven't. Unfortunately it will be a long story, because I have to covert a land machine I bought for this project. Expecting to have something to show in September at least.

Ok, finally, after doing some discharge and charge cycles, I can tell some conclusions.

First of all - it works just great.

Total battery capacity: 7.4v x 6.6Ah = 48,84wh

The voltage is fixed at 13.4v.

TDI power consumption (considering step up converter loss) is 6,85 Wh:

My battery pack is good for 7h hunt. 48.84wh/6.85 wh = 7,1

If i would build it using 18650 with capacity of 3400mAh, it would be fine for a 10h hunt.

The picture is showing charging process. The battery got 2.57Ah after 3h hunt.

Here is the model of the regulator I am using:

https://www.pololu.com/product/2890

It is not only about the hole, the distance between co-called ears is larger.

A part there is another thing to take care: detech coil is made to fit minelab shaft. 

So you have to replace the lower rod, or to put some shims.

Looks too complicated. If vanishing the warranty, you better grind down these plastic  pins in the battery compartment, so you'll be able to pack it with Samsung INR21700-50E 5000mAh - 10A valid for all day operation. Check nkon store. Whey are out of stock, but soon will be available again.

Thanks, Tony.

Can you tell me there  "volume" pot goes?

...whites uses the same amplified sound source for low impedance speakers and for piezos. It is good to know. Will check if I can see any difference in circutery.

By the way. TDIBH is quite loud. But there is a way to switch stock piezos to speakers headphones. Potentially it will help to differentiate low "whisper" targets.

The idea is the same to OBN Excalibur mode, but here we can use low ohm speakers, so there are plenty of options.    

Good luck, allthrough it looks difficult to fit this battery in the TDI housing due to the battery dimensions: 88mm X 70mm X 6.3.

70mm side looks too large.

What is the turn down voltage for AQ?

Building a battery pack for my waterproofed minelab etrac, I realized that it switches off at 9v, so no BMS was actually needed for my 3s lipo pack. 

I am not a huge fan of pulling battery out of the  housing for charging them, so detector is fitted with 4 pin ip68 connector which is used for charging/balancing. (Blue cap socket is the connector, see photos below).

So if AQ's lower voltage is 10v, there are li-ion cells with allowed low voltage of 2.5 volts, thus balancing can be moved to the charger.

Or another way round, the AQ was designed for lithium battery, so maybe there is some sort of protection circuit build in the detector already. 

TDI is voltage dependent, so going for 16v battery pack (freshly charged 4s lipo arrangement), you will have to go for even lower delay settings. ...which kinda surprise my, because even diving in rocky areas I rarely go lower then 15uS. 

With voltage regulated pack I can still use TDI with low 10uS delay, just because the voltage is fixed to 13,4 v all way through the discharge cycle.

Lower capacity of the battery pack in my case is due 2200mAh old scrapped cells i am using in it. It was an experiment, that turned quite successful.

Here is how detech 8" coil is sealed. I was thinking to open the coil and fill it up with the epoxy, but for the moment decided to glue the protection to ensure better sealing, just in case.

If the cable gland is sealed properly, I don't see problems.

Tony, good luck with your project.

Can I ask you to make a good photo if the PCB front side?

Can you also show where the headphones were plugged to?

I still have to decide whenever I will go for piezo or dynamic head speakers for my TDI project. But it nice to compare PCB, so I can track where to plug the piezos.

Here are two different pcb's older is from 2011 and newer is from year 2016.

I am starting a new project for getting land TDI sl waterproofed. It will be a long story for sure, but I ended up in the same situation and decided to go for Detech 8” Mono.

got my coil delivered to me a couple of days back.

Hello!

Here is a little feedback for regulated battery pack. it works just great! I set 13.4V and ended up with capacity of around 2900 mAh.

Great topic. Described modification looks not so difficult, so I'm thinking on buying TDI so from 2011 on barging price.

Here you have TDI sl PCB from 2016. You can see it is already modified.

Seriously thinking to put 7.5" white's mono coil on TDI beachhunter.

Had a short chat with white's and found that 7.5" coil is submersible and waterproofed:

Thank you for your interest in White's products.

No, White's does not plan to offer the TDI Beachunter with the 7.5 Mono Coil standard equipment.

Yes, the 7.5 search coil is waterproof and submersible.

Yes, it is a simple wiring issue to swap search coil on a TDI Beachunter.

7.5" might be lees floaty comparing to standard 12" coil....

8 hours ago, Skullgolddiver said:

To fill the upper side of the shaft is an option actually... Unluckily I'm not a big fan of melted stuff😨.

I'll try to realize some thin lead bars to suit the shaft under side with an hole and a bolt...or two

Solved:

if you attach 1kg diver weights it will do the same job.

9 hours ago, Skullgolddiver said:

Thanks for the link...I've seen already something similar on eBay UK If I correctly remember.

The old DD Minelab coil is already died, due to the past owner terrible care...In fact I hardwired the 8" to change it immediately when I purchased the machine from him.

You're going to waste your time trying to clean completely the minelab shell.

I did a couple of time some small reparations, and I would like to say that it is quite hard to remove the epoxy filler. 

I think the way to go is to talk to a manufacturer.

I think it will be possible to convince them for a epoxy filled coil if many people would like to get one. 

I am interested in one as well.

other option is to talk to detech (for example). there are many TDIBH users out there, and the waranty period of first detectors is running out. many people are searching for alternatives to 12" floaty coil. someone has to bring 8 -11" epoxy filled coil to the market...