Tesoro Cibola

[golfnut]

I can't understand how turning up the thresh makes it actually detect deeper?

Neither do I, if you crank the thrsh - need a closer or bigger target to ping

[Jerry]

I can't understand how turning up the thresh makes it actually detect deeper?

Neither do I, if you crank the thrsh - need a closer or bigger target to ping

The way you can use the threshold to make it detect deeper is to set it just on the edge of a background tone or accepting a little chatter vs running completely quiet. A threshold is just that. The target signal must be big enough to rise above whatever threshold point you set. Set it too far so everything is completely quiet at the risk of not hearing those deeper targets which have a weaker signal below the threshold level.

Another benefit of accepting a little background mutter or chatter is it is a constant reminder that everything is working. That is just the way I do it, some people prefer to run with the detector completely silent.

Jerry

[Davor]

Mine goes completely quiet on the very edge in the woods or far away from civilisation, so I have to swing a shovel occasionally so that I can tell it is still OK. Normally it scratches a bit there, and if subjected to some old car ignition noise it needs cranking up almost to the end.
Depth difference is, say, about 25%. For shallow coin shooting, especially in trashy areas just crank it to the end and enjoy the ride. It is fun.

[HECTOR]

Centralising - no. But adjusting it to be at the lower CCW side nulled for ferrite - yes. There is not much sense going any leftier than ferrite. Every realistic soil would be somewhere to the right from there.

My thought was to put a 50K trimpot in place of R39 to get the "balance" more center or slightly CCW. Right now, it "balances" with ferrite at 7.5 turns CW.

Threshold keeps your ears safe from chatter. So in effect it provides you with the deepest possible detection chatter free.

So, thresh on a detector is essentially the same as an audio compressor thresh? Now I see the logic in using a 3 position all metal switch. I'm also going to set my AM trigger switch up to switch to a slight hum for all metal, while I disc detect with the thresh set full CW.

[HECTOR]

Must have hit enter by accident

[HECTOR]

The way you can use the threshold to make it detect deeper is to set it just on the edge of a background tone or accepting a little chatter vs running completely quiet. A threshold is just that. The target signal must be big enough to rise above whatever threshold point you set. Set it too far so everything is completely quiet at the risk of not hearing those deeper targets which have a weaker signal below the threshold level.

Another benefit of accepting a little background mutter or chatter is it is a constant reminder that everything is working. That is just the way I do it, some people prefer to run with the detector completely silent.

Jerry

When I go inside my C to adjust the GB, I'm also going to set up the AM trigger switch with a fixed resistor so it will run in disc with the thresh cranked, then when I switch to AM, it goes to a low hum.
If anyone here has already done this, and have a good resistor value, please post.
Thanks!

[Davor]

I must correct myself on the threshold thing. I confused it with the sense control. In this particular rig the thresh control gives the extra boost, or not, to the low level signal. So the response will be more binary or more proportional. So you can actually make low signals appear as low level tones (proportional) which allows for some comfortable level of chatter (going deep), while cranking it up gives you more binary response (full beep every time) which calls for lower sense setup to make it comfortable when chattering. It is a matter of preference. I like it proportional.

[golfnut]

It would be nice if the threshold tracked the geb Ch output.

[Davor]

No need. There is a fine level of confidence and feeling of immersion into the ground you are searching when there is a little feedback all the time. It is the parts without noises that freak me out.

[N@SKO]

Final schematic without mistakes.No PIC added 4024.

[ivconic]

Omit U12 (4053) and use mechanical switches.
It will reduce pcb in size and spare few components.
Also instead 4024 single opamp based vco can be used too.
7660 would require sync with main oscillator but instead resistive coupling i would rather use capacitive.
I guess few pF would do just fine (22-100pF).

[golfnut]

If this goes to layout and kit.


Make pcb 100mm wide and 120mm long -so it fits in the rails of a quality project box.
eg



Have a gap exist between the Tx cct and the Rx preamp - with a copper gnd flood between for isolation.

Put the holes for the Pots on the edge of the pcb - so we dont have to add lots of wires to pots.
So the pots are in a row - mounted thru the pcb.

Steve

[HECTOR]

No need. There is a fine level of confidence and feeling of immersion into the ground you are searching when there is a little feedback all the time. It is the parts without noises that freak me out.

Funny you should say that I don't know how many times I've switched to AM just to see if it's working. That OMG! How long have I been"detecting" with a non functioning rig feeling. That's why I almost always run in AM in the woods, checking the GB often and feeling confident that I've missed nothing detectable.

[GSL]

Omit U12 (4053) and use mechanical switches.
...It will reduce pcb in size and spare few components....

...7660 would require sync with main oscillator but instead resistive coupling i would rather use capacitive.
I guess few pF would do just fine (22-100pF).

....Omit U12 (4053) and use mechanical switches.....
Undesirable - this will lead to noise interference.

......7660 would require sync with main oscillator but instead resistive coupling i would rather use capacitive....
This solution was used in the Lobo.

[ivconic]

....Omit U12 (4053) and use mechanical switches.....
Undesirable - this will lead to noise interference.

......7660 would require sync with main oscillator but instead resistive coupling i would rather use capacitive....
This solution was used in the Lobo.

What noise interference?

Solution used in Lobo might not work here too.

Anyway, this schematic is full of mistakes, same as "Tejon" schematic.
Will not work anyway.
Good luck!