My TGSL

[Tony60]

Hello everyone, today I powered for the first time the TGSL just finished; attached a photo of the PCB and the coil. It worked right away!!! The only non-original components of the schematic are the FETs (J310) and the 2n2907 (2n2905) The TX signal is about 15v AC. I tried to cancel the reel I would like to know if it is correct (photo of the scope). and now the problems; it seems to me little sensitive in fact a 1 Euro coin the "feels" to 15-16 cm only (can you improve??) I am still satisfied but I would like to improve it!
Thank you to all who will want to help me.
Tony60
On the scope top signal TX 5V div. 50uS and down RX 0,5V div. 50uS.

[dbanner]

I never like the way of this double d shape, it is difficult to balance for maximum sensitivity.
I prefer other double d shape which gives better range for nulling.
Next, put in threshold pot at last opamp(see silver sabre schematic), this gives overall better sensitivity control without chattering.
Make sure [email protected], [email protected](resonant with 15nf cap), if not, add or remove small capacitance. Must have proper for ground balance and discrimination to work properly and also affects the detection range(sens).
Also type of shielding, foil no good. Better mylar from cable TV house connection, strip it and use this for shielding coils.
Finally, for wet grass, use ungrounded Rx coil.

[Tibuck19]

Good job on the Board! I do not have a Euro coin, I am assuming its like a Canadian or USA penny ? i get a strong beep at 28 Cm indoors and outside, Like Don explained to me, the TGSL is not about the depth, it is about the good discrimination it has. they way i get the best depth is once i ground balance it i use a Silver coin and go back on the GB pot right to the point of where it just about to lose it.

[dbanner]

Your waveforms look very good, but there are other things which can diminish the detection distance. For example on my tgsl, I noticed tlO72 work better for one of the chips. Try different chips just to see for yourself. Also adding threshold pot like in silver sabre schematic allowed sensitivity pot to be cranked up considerably higher without chattering.
Tgsl circuit is really a mishmash of various blocks of old tesoro circuits. It is not a light version of golden saber as the name would suggest.

[Tony60]

Hi Dbanner Thanks for the compliments and for the tips for the reel; I would like to know which chip you replaced with TL072. I will see how the silver coil is built, I hope to find it.
Soon Tony60.

[Tony60]

Hello Tibuck19 Thanks for the compliments; Your TGSL works very well if you hear a 28 cm coin!! As I said to Dbanner also see the coil of silver (if I find it!!).
Soon Tony60.

[Tibuck19]

Hello Tibuck19 Thanks for the compliments; Your TGSL works very well if you hear a 28 cm coin!! As I said to Dbanner also see the coil of silver (if I find it!!).
Soon Tony60.

I have been told that the tgsl is able to get a penny at 34Cm Air test of course, I am not sure what chip to replace with the TL072, However i have gotten better results with replacing the 308 with tl081, I am using a board sold by silverdog which i belive to be Ver-3, might be different from your, Also if you lift Pin 5 of the 4024 you will get a deeper BEEP, i like that tone better then with the pin in place.

[Koala]

on mine (Bandido)an Eglish per decimal is 35 cm. This is a much bigger coin 31 mm

some of our smallest thin coin were only around 18cm

you can't compare a euro at 7 grams with a 2.5 gram US penny.

[Tony60]

Hi Tibuck19 Thanks for the info. My card is drawn by me but it is similar to that which is also on the Forum (mine is designed for the step of the components I had) however I will perform checks and see if you can replace the chip lm308.
All teh best T0ny60.

[Tony60]

Hello Koala, nice to meet you and thanks for the info that makes me more serene towards Tgsl.
All the best. Tony60

[Hyena]

If I remember correctly: use LM833 instead of LF353, TL071 instead of LM308 (and remove 100pF caps - C19 and C22). TGSL definitely must get over 1? over 30cm!
Play with Rx 15nF capacitor, try add 470pF, 1nF and always check if you are able to GEB properly and Disc have acceptable range...

[samsearcher]

Just started to construct the TGSL after a successful MPP+, The parts list that I have from Don does not seem to match the Siverdog PCB! The PCB is marked with component values instead of schematic refs.....is there a matching parts list/schematic anywhere?

[yatahaze323]

If I remember correctly: use LM833 instead of LF353, TL071 instead of LM308 (and remove 100pF caps - C19 and C22). TGSL definitely must get over 1? over 30cm!
Play with Rx 15nF capacitor, try add 470pF, 1nF and always check if you are able to GEB properly and Disc have acceptable range...

Hi Hyena, I heard of using the TL071 instead of the LM308 but I was unaware that I was supposed to remove the 100pf caps.

Besides using the LM833 and TL071 are there any other mods to the TGSL that you know of?

Thanks!

[Hyena]

Hi Hyena, I heard of using the TL071 instead of the LM308 but I was unaware that I was supposed to remove the 100pf caps.

Besides using the LM833 and TL071 are there any other mods to the TGSL that you know of?

Thanks!

Hi, you can leave 100pF there, Tl0x1 has pin 8 Not Connected so it does not matter if there is or is not 100pF cap.

I think there is not necessary any aditional modification.