Max another help

[metaldetector107]

could you tell me how to change the TX frequency because
mine 16.1 khz and the pin12 of 4024 same which should be half amount
as you mentioned.
i have changed all tx caps but didnot make any different.
about 8" OO coil what are the turns number?
so please help
thanks alot

[Max]

could you tell me how to change the TX frequency because
mine 16.1 khz and the pin12 of 4024 same which should be half amount
as you mentioned.
i have changed all tx caps but didnot make any different.
about 8" OO coil what are the turns number?
so please help
thanks alot

Hi,
if capacitors are as expected , like in schematic you need to increase inductance at tx coil: add some turns and you'll lower the osc frequency.

Don't remember now... for 8'' OO but think it's around 100turns for tx, maybe a bit more.Then add 5% turns to rx coil.

PS: don't worry about pin12 reading... probably your meter read 2x harmonic there... but there's maybe right value (half of tx frequency). Only way to be sure is checking with a scope.

Kind regards,
Max