hi guy,
some problems and i need some help ...
first time i build a tgsl on selfmade pcb, at the first test i blow the lf353 and the lm 393 at rx stage by placing the 353 in opposite direction. both get very hot and i decided to replace both with new parts. and i decided to build the pcb from driscoll from page 113 with the same parts. so i removed all parts from pcb and placed them on new one. at this time i noticed that my dealer send me 2k2Ohm instead of 1MOhm. thats the prehistory
question: what parts could be damaged in case of taking 2k2 Resistors instead of 1M and whhat parts could be damaged if i turn the lf353 at 180°?
next ...
i finished the tgsl on the new pcb with new 353 and 393 on rx stage and real 1M. Coil is nulled. first test...
no tone ... i removed center tap from pcb ground and i get a tone.
second try ...
i switch it on and the machine starts to beep for many times. no change if i turn geb or sens pot, when i turn disc pot the beep stop (the machine is in all metall mode ?!?!?!). if i put some metall over coil i get an answer for detection and the beeps return. when i switch to disc mode i have no beeps and a good detection 1 euro at 25 cm. but the detection tone if the coin has a distance to coil from around 10cm is somtimes a double beep.
but... disc dont work ....
i can turn the pot in any dirction with no change. in every position i can detect aluminium, iron and 1 euro.
so ....
why it doesnt work with center tap on gnd
why i have an endless beeping in all metall mode
why id have no disc in discmode
some ideas ? i have no more ideas ... need some help pls
coil: wire 0.28 (dont know if it is with or without varnish)
DD dimensions like ivconics recipe
tx 104 , 19.7Ohm , 14,6KHz at tx stage
rx 110 center tapped, 27,7Ohm
nulled to 0,000V very easy
all parts are correct connected
THX
http://www.geotech1.com/forums/attachment.php?attachmentid=6621&d=1222438708
some problems and i need some help ...
first time i build a tgsl on selfmade pcb, at the first test i blow the lf353 and the lm 393 at rx stage by placing the 353 in opposite direction. both get very hot and i decided to replace both with new parts. and i decided to build the pcb from driscoll from page 113 with the same parts. so i removed all parts from pcb and placed them on new one. at this time i noticed that my dealer send me 2k2Ohm instead of 1MOhm. thats the prehistory
question: what parts could be damaged in case of taking 2k2 Resistors instead of 1M and whhat parts could be damaged if i turn the lf353 at 180°?
next ...
i finished the tgsl on the new pcb with new 353 and 393 on rx stage and real 1M. Coil is nulled. first test...
no tone ... i removed center tap from pcb ground and i get a tone.
second try ...
i switch it on and the machine starts to beep for many times. no change if i turn geb or sens pot, when i turn disc pot the beep stop (the machine is in all metall mode ?!?!?!). if i put some metall over coil i get an answer for detection and the beeps return. when i switch to disc mode i have no beeps and a good detection 1 euro at 25 cm. but the detection tone if the coin has a distance to coil from around 10cm is somtimes a double beep.
but... disc dont work ....
i can turn the pot in any dirction with no change. in every position i can detect aluminium, iron and 1 euro.
so ....
why it doesnt work with center tap on gnd
why i have an endless beeping in all metall mode
why id have no disc in discmode
some ideas ? i have no more ideas ... need some help pls
coil: wire 0.28 (dont know if it is with or without varnish)
DD dimensions like ivconics recipe
tx 104 , 19.7Ohm , 14,6KHz at tx stage
rx 110 center tapped, 27,7Ohm
nulled to 0,000V very easy
all parts are correct connected
THX
http://www.geotech1.com/forums/attachment.php?attachmentid=6621&d=1222438708
there are a number of movies where MDs are shown... uhm... let me think at an old movie with Jack Lemmon... something around years 1987-1988 I think (I was at school at that time... and my school paid the ticket... otherwise I wasn't really happy to spend money to see that kind of movie... you know... I like much more the sci-fiction-splatters like Alien etc 
) 
the kind of humor that some people have when they see someone digging in the dirt...of a beach. 
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