Surfmaster PI dual field?

[kuraja]

Is this schematic correct?

[Micheal]

I have the whites DF its a very good machine if you can make it...do you have pcb drawing

[kuraja]

I will be able to make one, I just need a confirmation about this schematic being alright and if its a real deal.

[Harp]

Yes, it work for me. I make it on the testboard.
Don't like two things: Sens pot (my opinion- sensitivity should always be the maximum), is not needed.
Move detection - it's not so good for very small objects.
Is it the real deal? I don't know, it's my first - it seems to me good.
Coin (20mm dia ferrite) detect at about 15cm, with disordered coil 180mm inner dia.

[bernte_one]

can you post a better quality shematic and the layout, please ?

[Harp]

Schematic is available on https://picasaweb.google.com/112865837265488056150
Note that pictures of testboard do not represent this schematic. It is my new experiment for now.
Layout has not been made yet, still looking for the best solution.
With this setup of testboard and coil, I detect 19mm aluminium coin at 30cm distance. But I'm not satisfied, it's not stable threshold.
When finish performing a test, I will open a new thread with a lot of questions.

[bklein]

Why C16 is 100uf and not 220uf?
Did you try the alternatate approach to the 7660 circuit with its own oscillator (not locked to 555). This is used in the Oxygen circuit.
Just wish people would explain why they deviate from a commercial published circuit...
Here the changes just get carried forward and maybe the guy just didn't have the correct parts at the time so he documented what he used...

Barry

[Harp]

Actually, I thought I was completely out 7660 and put 7905 instead.

[bklein]

Actually, I thought I was completely out 7660 and put 7905 instead.

huh?
you mean you used another battery for negative 12V into a 7905?

[Harp]

I'm not sure, but first I thought of something like this.
Would it work?
https://picasaweb.google.com/1128658...78090982173762

[Qiaozhi]

I'm not sure, but first I thought of something like this.
Would it work?
https://picasaweb.google.com/1128658...78090982173762

The problem with your circuit is that there is no common reference point. The +5V output is referenced to ground, but the -5V output is referenced to +12V.
If you replace the 12V battery with two 12V batteries in series, and use the point where the two batteries are connected as ground, then it will work. Obviously you will also need to connect the GND pins of both regulators to ground.