ARADO 120 SCH& PCB

[nimalgr]

WHICH IS THE PURPOSE OF VR1 TRIMMER???

[nimalgr]

HELLO EVERYBODY!
COULD SOMEBODY TO TELL ME ABOUT THE COIL OF ARADO 120 (HOW TO MAKE IT) AND HOW I WILL ''NULL'' IT!
THANKS

[Noro]

hi Andreas, congratulations for explanation, please tell me coils are shielded?
thanks

[satdaveuk]

Im going to build this detector, has anyone else here built it?.
I have a small varibal 150pf out of a radio if required, seems by old posts that was the only bug bear.

Regards

Dave

[Davor]

Ardo has very interesting detectors.

[Peter Jones]

Has anyone completed one of these yet ? I am interested in the "OO" coils, perhaps as replacement/upgrade for original machine ?

[mindfree]

Thanks Andreas for this interesting project and wonderful explanation.
Can't wait to get a break from my day job and start building one.

[simonbaker]

Thanks Andreas, it looks like nice basic circuit to try.

No ground balance I think.

If Rx resonant to Tx frequency, that is nice for sensitivity -- but will it stay in tune? Maybe drift easily?

I hope people build and try it in real ground, very interesting.

Cheers,

-SB

[aft_72005]

Hi Andreas
To give Thanks for your Nice work .
Best regards.

[ANDREAS]

Hi Patrick
I wait finish the first PCB , next step are coils and finaly is electronic varcap.
best regards

[Patrick]

Yes is true , but my Arado build two years ago, i don't put this variable capacitor.
You know is very difficult resonate same two coils Tx/Rx. For this application Arado use this variable capacitor.. etc
My method is simple for your all. After you build PCB , you must build a electronic-cap with range 50-300n. With this electronic-cap we can make a fine tune Rx coil.If you find this parts (example 101,5n) then replace with normal capacitor/capacitors and only difficult point is a "null" Tx/Rx. With this method we don't need variable capacitor between Tx/Rx
best regards

Hi Andreas
I find it interesting how your finely tuned.
Have you a schematic for electronic-cap ?

[ANDREAS]

hi sharky i cant found 3v9 diode any solution ? and for cd4017 i have hct4017
i will star my pcb after solving this 2 problem br!

Use other jener between 2V9- 4V1. I think you have not problem, if we see problem.. sorry but you must be find 3V9 jener. Use Hct4017, i am sure... it's work. C17,C18 you don't put now your PCB. After resonate Tx coil, you know if C17,C18 are right or not
best regards

[salim]

Yes, but is not time for this. We wait the first PCB

hi sharky i cant found 3v9 diode any solution ? and for cd4017 i have hct4017
i will star my pcb after solving this 2 problem br!

[ANDREAS]

According to Ivconic, there is a large variable capacitor connected accross the TX/RX coils....

Yes is true , but my Arado build two years ago, i don't put this variable capacitor.
You know is very difficult resonate same two coils Tx/Rx. For this application Arado use this variable capacitor.. etc
My method is simple for your all. After you build PCB , you must build a electronic-cap with range 50-300n. With this electronic-cap we can make a fine tune Rx coil.If you find this parts (example 101,5n) then replace with normal capacitor/capacitors and only difficult point is a "null" Tx/Rx. With this method we don't need variable capacitor between Tx/Rx
best regards

[technos]

Do you remember the variant with electronic capacitor for to helping the tune?

According to Ivconic, there is a large variable capacitor connected accross the TX/RX coils. After some thought, this does not make sense to me. I do not have (or had) access to this UK machine, so I do not know how this works.

Other coils use a trimmer cap, or more commonly a fixed value capacitor connected in this way accross the coils. If it is something that needs very infrequent adjustment, it makes sense to use a trimmer cap on the circuit board rather than an expensive mounted tuning capacitor.

I searched parts sources, and the large varicap diodes have become rare and/or are too expensive (as much as the tuning capacitor!). So that doesn't seem practical either.

If there is a need for an occasional tuning, it would make sense to use a trimmer in parallel with a smaller (and cheaper) available varicap diode.

I hope Andreas keeps us informed on this!