TDA 0161 Homebrew pointer???

[Comp]

Picked a couple of these chips up to play with,.... {TDA 0161} as per this data sheet,... anyone played with it before???? I found a reference on Gary's website,.. any one else had a play???
http://www.dz863.com/circuits-6-8139...ation-Circuit/

Like most detectors, I'm convinced the coil is the heart of the system.....

Anyone??? thanks in advance,....


Cheers, Fred

[Skippy]

Does look functionally close to the Cherry CS209 part. I suspect performance is likely to be similar if the coil is similar. The ultimate sensitivity of these circuits appears to be limited by their tendency to respond to the earths' magetic field. Moving the probe will cause a trigger.

[chemelec]

I have stock on Both the CS209 and the TDA0161's.

Both work Very Simular and are Only good for very close detection distances.
(Typically 1/2 inch max. MAYBE 1 Inch if your really lucky.)

Both also require a coil wound on a "TINY" POT CORE for Greatest Range.

Moving the probe DOES NOT casue it to trigger by the earth magnetic field.
Or it never has on any of the circuits I have built.

I'm Off to Chile & Peru on Thursday for a 5 week Holiday, so I probably won't be on here much till March.

Take care....Gary

[Skippy]

I speak from experience tinkering with the Sherlock DTS pinpoint probe, which is based on the Cherry device. The probe is a 3/8 inch / 10mm diameter ferrite rod approx 80 mm long.
On it's highest sensitivity setting, it definitely will trigger when moved. The movement needs to be in particular directions, linear translations don't seem to affect it at all, and rotations only do so in certain axes consistent with moving a coil through the Earth field.

[Dragon44]

The Fair Rite Co. core, Part Number 4077312911, or similar, works very well with this IC. I have found that around 150-200uH works best w/a 200-220pf Cap. I have built many pinpoiner probes using this chip. I can get it to sound off on a Quarter at 1 1/2 inches with some tweaking of the components. Of course there are many other options, especially since the CS-209 is obsolete.

[satdaveuk]

I have stock on Both the CS209 and the TDA0161's.

Both work Very Simular and are Only good for very close detection distances.
(Typically 1/2 inch max. MAYBE 1 Inch if your really lucky.)

Both also require a coil wound on a "TINY" POT CORE for Greatest Range.

Moving the probe DOES NOT casue it to trigger by the earth magnetic field.
Or it never has on any of the circuits I have built.

I'm Off to Chile & Peru on Thursday for a 5 week Holiday, so I probably won't be on here much till March.

Take care....Gary

Good on you Gary
I need a good holiday, not been on here for a week or so cause of work load.
I was wondering about making a coil for pinpointer based around a old cotten thimbal, maybe a bit on the big side but so what, normally dig a hole 12" anyway.
Just a thought cause these home brew pinpointers seem to be a bit lame if you take my meaning when compared to whites/garret pinpointers.
The best one I ever made was based around a BFO circuit in a very early addition of everyday electronics early 80s.
Regards

[Comp]

some useful starting point info there, guys, Thanks a lot!!!!!


Cheers, Fred

[Dragon44]

@Satdaveuk - I think not. Heck, my 'modified' GPD-902 probe (Dan Clark) outperforms the Garrett and Whites. I know two guys I hunt with and they use them. Also, I added a white LED and a vibrator motor, so it suits me just fine...The 67801 Stud Finder from Harbor Freight also detects a quarter at 1.5 inches, stock. I will be posting the directions to modify this unit very soon.