Non motion detector

[Detectorist#1]

Further improvement of the stability of DC work point ( increasing of max non-motion time) will be achieved with change of the analog switches type CD4066BE with MAX4066ACPD. First type have typical switch-off current
of 100pA (max 100nA at 25oC). Second type have max switch-off current of 100pA at 25oC.

[Detectorist#1]

Attached is the schematic of non motion detector with improved DC stability of the last amplifier.

[Detectorist#1]

Hi Ivica,

I have idea for analog non-motion PI detector. The idea is generate after reading of similar software solution from George Payne. Auto-tuning works all time when no signal from the target. When the signal from the target is received - the auto-tuning is disabled. Attached is the schematic of the detector for your information. What is your opinion?

[ivconic]

Don't make that pcb; until you modify the power supply part and restore the original instead of my experimental changes.
Because obviously my experimental changes are not good.
And what you are asking of me now; sorry but these days I am not in a position to do such things.
But if you go back to page 8 and pay attention to the posts #107-#118; I think you have enough "material"to calculate what interests you.
I started this topic a long time ago, did something, then put it aside. In the meantime, I did some other things.
And forgot all this! It's like I've never done it and it's like it wasn't me.
Is it because of age or do I become easily forgetful... But now I read and reviewed the whole topic again. And I was surprised how much there was!
I might come back to these works. The idea is to make non-motion.
But to add an auto-zeroing circuit that will keep the threshold constant at the level set by the potentiometer. This is crucial.
The next thing that must be done is the addition of a circuit that will change the pitch of the audio depending on
a) the strength of the detection,
b) depending on the conductivity of the metal.
These two options will be toggled. Ot to engage the meter to serves for one and audio for another.
Under the b): changing pitch in audio is a kind of "discrimination".
It does not discriminate anything, but it indicates the type of metal by the pitch of the sound, or. conductivity.
a) will serve to assess the depth of the target and b) to assess the type of target.
That is my final wish, to successfully make such a non-motion.
But things are getting more complicated and I don't have a lot of free time to deal with it continuously.
It is obvious that the participation of other people is also needed here.

[algan]

I will make your CM5000 board, but I want to try with DD 28 cm on the patent it shows that the RX has a 27NF capacitor, can you just connect 1 and 2 pin in place of the TX and measure what frequency it has, that way I will be able to calculate the same way, how exactly will the inductance of RX be for DD 28 cm


somewhere it was written that you are looking for a generator with a midpoint similar to QUEST, this is also such a generator from the FISHER 1260-X scheme

[ivconic]

Probably due to internal components; I can't measure inductance.

[algan]

This is the schematic of the ivconic CM5000 should be able to measure the inductance and ohms of the RX between pin 3 and 6

[Gunghouk]

Beachcomber 4B connection.
Resistance :
Wh - Rd = 1.06
Wh - Bk = 2.04
Rd - Bk = 3.08
GN - scrn = 5.5, L = 470uH

[Gunghouk]

Useful info here as I've recently purchased two Beachcomber 5D detectors + spare main board which came with three 4B coils. Seems one detector works while the other boards don't. All coils seem fine though fitted with a mix of broken/perished 5 pin din () and 5 pin GX12(?) plugs.

[algan]

Hi ,ivconic can you measure from the original CM5000 coil on the RX how many millihenries it is and what ohms it has? Thanks.

[Davor]

I also don't think there is any advantage of non-motion discrimination modalities. If discrimination is delegated to the pitch of the sound, then you are not losing the information of existence of a target if you lose only discrimination information because of slow passes, but keep the information of a target beneath.

[dbanner]

Oscilloscope at point A and B on circuit should show smooth sinus waveforms 180 degrees out of phase. Adjusting sensitivity trimmer so not to overdrive subsequent preamp stages. Point C in ground balance mode is phase shifted.
Output of first opamp is sinus.

[dbanner]

The output of the CA3130 is Cmos and is rail to rail. The output of the CA3140 is bipolar and is not rail to rail.
C1 is in the original search coil assembly. Changing Rx resonance can change gb range.
GB trim on original schematic is 47k. I notice on your schematic (from video) it is 10k. The phase angle will be different.

[ivconic]

After a long wait; pcbs arrived from china. I made one copy of White's Coinmaster 5000 G.E.B. / D on a different pcb, which I drew myself.
I don't have data for the coil, so I connected the original coil in the first test.
It worked.
But I notice two things, two problems: it doesn't have that "depth" to the air like the original detector and it doesn't see iron in any
of the operating modes???
In Disc mode it is normal not to see the iron but in GEB mode you should see the iron very clearly.
I put all the components as on the original, except for the transistor. Instead of the original ones,
I put BC557/547 and BC327/337. And instead of CA3130 I put CA3140.
All the "potentiometers" (currently trimmers on the pcb) seem to work...
TX frequency is 5.115kHz. And the amplitude is 11-12Vpp.
Now I have to further investigate why it behaves like that.

[ivconic]