IDX-PRO+VDI

[CDI]

i measure Tx voltage with multimeter, turn it to rage of 20v~ and attach red probe to tx connection(when tx coil is on) and other probe to gnd ... unfortunately i dont have oscilloscope...

Set AC voltage on multimeter in range of 200mv and check pin 3 on NE5534.
Btw, oscilloscope is very useful, but md can be made to works good without him.

[heyran]

dear CDI
I checked Tx voltage,it's 4-5 volts and changed ICs one by one and used other frequency-as you said. apparently everything is ok but the md has poor depth ,1euro can hardly be detected in 20cm , how can i boost the depth?

this is another photos of my md board

[heyran]

how much voltage on pin3 of ne5534(U1) is optimal?

[CDI]

how much voltage on pin3 of ne5534(U1) is optimal?

Must be less than 200mv. Next thing what u can try: Delete R25 and set trimer 2-5K, this will give u hiper sens.

[heyran]

thank you CDI, i changed u1 and place op177 original , alot of problem solved, depth is good now, 1euro about 38cm,it's ok?

[CDI]

thank you CDI, i changed u1 and place op177 original , alot of problem solved, depth is good now, 1euro about 38cm,it's ok?

That's almost finished, you can try to get 45 cm for 1 euro, but... there is a good chance to go into instability.
Better leave like that if is stable on soil.

[heyran]

now ,it detects 1euro in 50cm!
thanks to all ,especially dear CDI...

[CDI]

now ,it detects 1euro in 50cm!
thanks to all ,especially dear CDI...

Nice, original IDX does not have that distance.
Did u tried on real soil? Is it stable? Novfalse signal's?

[heyran]

50 cm in air test,I don't try it at real soil

[CDI]

50 cm in air test,I don't try it at real soil

Try outdoor on real soil, i hope u will not disapointed...

[seadoggy]

now ,it detects 1euro in 50cm!
thanks to all ,especially dear CDI...

Did you test of outdoor?but i think with that deep you will have wild machine in real soil!
Regards

[gaby_sult]

Hard to believe with (U4 - LM393P) 50cm,

[gaby_sult]

Tx must 8-9 be volt's, depending on which voltage stabilizer you are using.
Try to change one by one IC. Next thing you can try is to change frequency.
Use 330N for Tx and 8-10N for Rx stage.
Also, R32 can be little raised, instead of 220K try to put 370 - 470K for slower reactivity, this will give you more depth.
All this can't help if coil is not nulled optimal.
Regards

With respect ...
Can you help me please with an explanation?
I use LM7808 and TX voltage is 5V~, how can get 8-9V~ in TX?
Regards

[CDI]

With respect ...
Can you help me please with an explanation?
I use LM7808 and TX voltage is 5V~, how can get 8-9V~ in TX?
Regards

Easy, my voltage regulator is lm7809 which provide 9v.
I measured 9v on tx without coil.
Regards

[der_fisherman]

Data sheet LM3808 regulator chip....

You may find this nteresting reading:-
https://www.fairchildsemi.com/produc...rs/LM7808.html
Regards
Andy