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Tdi big box vs sl
Posted by: stephenscool
Date: March 15, 2018 09:01AM
Has anyone tried both ? Big difference in depth or other major differences?

Re: Tdi big box vs sl
Posted by: rogue
Date: March 17, 2018 08:06AM
from what ive read and seen on you tube...there is only an inch of difference and with a bigger battery the sl is equal....but i only know what ive read.... the internet never lies....right? lmao

Re: Tdi big box vs sl
Posted by: stephenscool
Date: March 17, 2018 10:05AM
Some differences in the gb and a couple other things... that won't effect beach hunting in all metal mode. As far as I know.... Never had a big box

Re: Tdi big box vs sl
Posted by: Reg
Date: March 17, 2018 11:11AM
I own several of TDI's and SL's and what rogue says is basically correct on depth difference. On all of my units, they all measure the same given the same coil and battery, except the SL lacks about an inch compared to the TDI when using the different voltage batteries. Match the battery voltage and the depth becomes basically the same.

As for using bigger coils on the SL, that is very possible also. In fact, the baby SL is the SPP and it was sold with an optional 20" coil at one time. The key problem with using larger than 14" coils is mainly because of internal detector filtering. Sweep too slow and you lose depth. Sweep too fast and you lose depth, especially on small objects such as a small coin or button size objects. A simple test by the owner will easily display this condition especially on weak signals. The key is to experiment to find the ideal sweep speed.

BTW, lock the delay at 10usec and remove the conductivity switch and you turn the SL into the SPP.

The TDI and the SL use completely different circuit boards, yet, technically are almost identical electronically. In other words, the overall gain of the TDI and SL circuitry is almost the same, which means they should get the same or very similar depth if using identical coils and batteries.

I believe the SL motherboard will fit in the TDI housing and was designed to replace the original TDi motherboard.

Reg



Edited 1 time(s). Last edit at 03/17/2018 11:21AM by Reg.

Re: Tdi big box vs sl
Posted by: rogue
Date: March 17, 2018 02:17PM
thank you Reg, you answered my coil question from another thread about running a larger coil....

Re: Tdi big box vs sl
Posted by: rogue
Date: March 17, 2018 02:47PM
actually Reg, I would like to personally thank you for all your posts. I have done a ton of reading from this site and others before i bought this machine, Your posts are very informative and helped me greatly understand the mechanics of this detector.

Re: Tdi big box vs sl
Posted by: stephenscool
Date: March 18, 2018 01:49AM
Thanks reg. For 1" depth difference I might just stick with the sl. The smooth threshold is a winner in my book

Here was the source for the above information. Gb differences were between the original and pro. Never had either or opened up the box

https://www.findmall.com/read.php?73,1435671



Edited 2 time(s). Last edit at 03/18/2018 02:01AM by stephenscool.

Re: Tdi big box vs SL
Posted by: Reg
Date: March 18, 2018 06:09AM
Keep in mind that Eric Foster started out with a regular TDI and made field changes while he was in OZ to develop the Pro model. So, he added a vernier GB control by simply inserting another pot in line with the main GB, removing the internal volume control from the motherboard and adding it to case so it could be adjusted by the operator. Finally, he changed two capacitors on the motherboard. That's it for the changes.

Place a TDI and a Pro motherboard side by side and compare all other components you will find them to be them to be identical. Take the TDI and change two capacitors, add a vernier GB pot and remove the pc board volume control and add an external pot and you have a Pro motherboard.

The reason for the vernier GB control was to make ground balancing easier in the OZ bad ground. The change of moving the volume control to make it operator adjustable was because uses a chip for the audio (LM386) and it was found one could reduce the warble intensity a little with the right volume control setting.

Of the three differences, only the change of the two capacitors is needed to make a TDI into a poor man's Pro. On the TDI, the capacitors are C59 and C60 (both are .22uf on the TDI and the same two caps are .1uf on the Pro). Keep in mind these two caps should be matched to 1% and be a quality metalized film or polyethylene type. Do not use an electrolytic or other type of cap.

On the SL, the part numbers and values are totally different, so absolutely DO NOT CONFUSE THE TWO machines or motherboards. People have posted some really stupid things on other forums that will result in miserable results.

One other note, almost all of the people who had their TDI modified by my buddy Paul, had the Cap change along with the noise reduction mod done so they already have a poor man's Pro. I can't believe that one of these modded units sold for such a low price recently on the (*bay) auction. DUMB!!!!!! People wanting a Pro missed a really great deal.

Reg

Re: Tdi big box vs SL
Posted by: Jim in Idaho
Date: March 18, 2018 11:48AM
Really good to see you posting, Reg. Hope all is going well. No big news from Idaho, other than I got the patent application in on the "sweep" jig. Took ahuge amount of hours to get that finished. Now waiting for spring.:-)
Jim

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