IGSL

[Davor]

Hi What is your suggestion to davor coil size smaller and the target for the small ones I don't like the size of a large coil for isgl musketer

See what size is right for you and make a coil of that size with roughly the same inductance as the original.

[liekwang]

Hi What is your suggestion to davor coil size smaller and the target for the small ones I don't like the size of a large coil for isgl musketer

[Davor]

You could avoid foil if you have centre-tapped Rx coil, or if you put a graphite shield instead. Otherwise your coil will show instabilities in proximity of every object.
When using foil, you must leave a gap in coil wrap to avoid short circuit, and you have to connect foil wraps of Rx and Tx in a single point on each foil. If foils are touching at 2 points you actually have a short circuit.

[liekwang]

?I can not wear AL foil do I have to wear AL foil for TX and RX coil

[Davor]

Perhaps your shield is not connected to signal ground?

[liekwang]

I already follow your advice but still sensitive to red brick and stone River, seems to be defunct and GB in action against swing my hands near the coil what else do I need to do

[Davor]

This diagram is a part of a larger schematic with many more mods than this common GB mod, and I indicated only U4b and U4d for this particular mod. Changes around U4c are for a different mod that eliminates U12, but you don't have to worry about that. Just make corrections as indicated for U4b and U4d, and you'll have a common GB control on your front panel.

[liekwang]

cast swap 8 and 9 pin ic lm 339 U4c connected whether you mean it

[liekwang]

[liekwang]

?R74 connected where P2 heading over to where it connected to the bottom where R13 connected cor swap pins 8 and 9 must be connected to the lm33c U4c which makes me confused must be connected wherever you and your sorry troublesome R18 towards where must be connected

[Davor]

The jumper is a short piece of wire soldered directly between these pins on solder side of a PCB, as they are pins of the same IC. Potentiometer is as described in the above drawing. You can use 100k potentiometer.

[liekwang]

?Davor please show the deleted scema potentiometer after removed should be headed where the coaster and please show a jumper at scema let me know to where it should be deleted please be jumper thanks davor

[liekwang]

?Davor thanks your suggestions later will I pelajarin scema from you can be sensitive to a brass coin got 30 cm but only beep sound tik tik are not strong and coin along with red brick test coin above the bricks sound similar to the sound of coin could not distinguish

[Davor]

It is not complicated. You need to use a single comparator to drive both GB channels of Fe and Non-Fe with same signal. To do that you need to set comparator U4d high, and easiest way to do that is by removing the trimmer and connecting the "-" input to negative voltage. Next you simply need to connect pins 1 and 13 so that U4b does all the GB work. This results in common GB drive in both Fe and Non-Fe channels. To have a real potentiometer at hand to adjust GB on the go, you need to replace a trimmer potentiometer on the PCB with a real potentiometer on the front panel, so you simply extract a trimmer Tr1 and place two wires in it's place, and connect a potentiometer. Beware - the high impedance of this line is prone to picking up various EMI, so twist the wires that go to the potentiometer. Now you have common GB control on your front panel.

[liekwang]

?Davor I have not understood your suggestion to position potentiometer to connect where and you made me understand only pin 1 and 13 are connected please give me ways I can understand with scema you provide