Did the TDI SL second mod yesterday...

[Orbit]

You have to be aware that when changing sync polarity is where the point of oscillations occur. You want to keep the switching point far away from sampling times, in the TDI it happens when TX turns on. Oscillations last only few microseconds, so there is no noise.

Hi Eclipse ! Yes just by turning the polarity noise is still present the question is whether tx can be inverted with respect to s1 s2 s3 and s4 to s5 or sync when we turn the polarity can eliminate noise , or must and tx be polarized like s1 s2 s3 and s4 and only in that case when polarization sync inverted and of course cover the whole window cancels the noise...

[eclipse]

One TX cycle the synchronization pulse is HIGH, then the next cycle it goes LOW.
Sync pulse has no relation to TX, S1..S4 except for the fact it must be switched far in time from S1..S4 and it is set to have 50% duty cycle (TX/2) which means it works around 1.5Khz for the TDI.

[Orbit]

Hi to everybody!
Am I right TDI-SL is the latest version ? I primarily want to ask are all versions the same as far as depth is concerned or the version is TDI -PRO deeper?
And do all the versions have noise without threshold tone one originating from LM386 , when we move our ear near the speaker ?

[eclipse]

There's a new version TDI beach hunter but probably nothing special compared to the SL, probably smaller board that doesn't have the empty IC drawn in the SL board.

[Altra]

Hi to everybody!
Am I right TDI-SL is the latest version ? I primarily want to ask are all versions the same as far as depth is concerned or the version is TDI -PRO deeper?
And do all the versions have noise without threshold tone one originating from LM386 , when we move our ear near the speaker ?

Hi Orbit, I have read on the forums the TDI pro is a little deeper than the SL. The Pro used a 14v battery and the SL 12V. Not sure if the TDI's sold by White'sever used a LM386 in the audio? The schematic I posted was from a prototype test unit, I'm sure there were many changes to the final units. The LM386 is prone to oscillating and ac hum pick up. If I understand what you are asking about the noise with the threshold down? Try a different audio output circuit (transistor) without using a LM386

[Orbit]

Thanks for calling so Eclipse and Altra!

Personally, I would say that something is deeper but I wanted to hear your opinion it's not just about power PRO has more amplification with integrators of SL!
Yes the question was that noise with the lm 386 i tested other options with LM4818 and LM4861 but the noise was still present especially feels when the coil is connected, with transistors no noise at all crystal clear sound !
I was wondering why Whites they did not put transistorsreally weird! With a pair of transistors there is no noise at all and the threshold is very soft and fine!

[Carl-NC]

TDI-pro is deeper but not as smooth.
TDI-SL was designed from the beginning to fit the Beach Hunter box so it is exactly the same board.
TDI-SL also uses the LM386. I don't recall audio noise but that was a long time ago.

[Orbit]

Hello Karl!
I read in one forum specifically Detector Prospector, that Reg did mode for noise suppression, is the mode found in TDI SL actually the mod that Reg was doing with those diodes?

[Carl-NC]

Yes, the SL incorporated Reg's mod.

[Orbit]

Yes, the SL incorporated Reg's mod.

Thanks Karl

[Orbit]

Hi there TDI users have you noticed that when the weather is warmer the devices work more stable while when it is cold have a trend to have a noise?
Question for Karl : Hello do you noticed that the active clamp moves that is, the voltage changes at the exit of U12_2 pins 7 if cooled or heated by a blower U12 TDI-SL Whites and for cause when it's cold TDI be a little unstable and when it is hot it is completely stable but the detection is smaller?
All the best!

[dbanner]

My intuition says that it is likely the coil susceptability to extreme temperature deviation rather the the underwhelming circuitry response.

[Jose]

What I noticed in my GS5 clone is that if the "autozero" circuit setting is advanced, at the edge of the cut, it is possible to decrease noise, but also some sensitivity,
If this adjustment is made in summer, it may lock in winter and require a new adjustment.
In general, where I live, the external electrical noise is higher in summer than in winter.

[Orbit]

Hi Karl !
For the first time, I tried to eliminate the third filter on the TDI-SL I put a jumper across C42 I did not remove the R75 .. Tdi-sl gets deeper ! But I have to reduce the sensitivity by 50 percent because it seems that more geb is not working properly actually how I wave the coil over the target in the ground to the left it detects the target, but it carries away the tone, and to the right it is much more difficult to detect the same target so, in my opinion, that mod doesn't work at all maybe I should have downloaded R75, I didn't try it I put the third filter back onI will probably try again only when I assemble the second TDI device..
The question is, did I make a mistake somewhere? Specifically, did I give the fluctuation of the signal, maybe the R75 is affected?

[Jose]

I tried to modify the high pass filter (470n; 5.6M) by changing the values of R and C, to get better gain, but unfortunately the GB is affected as you mention.
By making a C-bridge (470n), it improves the sensitivity, but again, we affect the GB.
The question is, does anyone know of a mod that solves both problems?
It is worth a try, because the improvement in sensitivity is important.