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early kits had lmc, later ones had LF...
Feel free to help..
Feel free to help..
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I already have the Lf347 chip in the project. So that is not the problem.
It likes to go off into chattering modes.
Even targets do more than a Chirp - often a target sweep causes a half or one second chatter.Comment
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to me by some false signal, I tried to turn up the ground but I can not solve, however I work I always sensitivity 'maximumComment
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Now I try to attach the ground wire the better, but to me is that every so often does make the false signal.
http://s740.photobucket.com/user/ven...13a88.mp4.htmlComment
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ampirate, add extra cap to you tx to go to about 7k and see if any better.. may need to tweak rx cap for some sense,, then try reject ferrite,, take vdi off for this.
get you coils sheilded etc to move forward..Comment
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I am confused with this persistent Chirping problem.
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I do find an odd situation that I want to Question though ...
Why does the COIL and CABLE Instructions specify to have the TX Wires directly adjacent to the RX Wires within the SAME Shielded Cable ?
Why Shield the TX and RX lines if they are Not Shielded from EACH other ?
Doesn't this provide an obvious and Direct Interference crossover Problem ?
I pulled the TX lines out from the Shielded Cable - leaving ONLY the RX Wires within the Shielded Cable.
And, this got rid of a LOT of the Chatter !
I have been wondering why this Chattering problem seemed to start - after I added the Shielded USB Cable Solution ...
Maybe this is a cable problem to keep in mind ... ?
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I tried adding a second Cap to the TX Coil, giving 2mF on there now.
Got rid of a little more noise and increased the range a little.
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Still debugging though...Comment
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Okay,
I found a stupid little problem , I found with the Oscilliscope.
I had made a new set of Coils and wired them backwards yesterday.
So coil TX went to board RX , and coil RX to board TX.
Still gave half reasonable responses though ...
Rewired that and I am back to 16V p2p TX, and 1V p2p RX at about 6.3khz,
but still have a chatter problem - though.
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Chatter problem :
1. Sensitivity and Threshold do Not seem to affect the Chatter , but they do affect the Target Range
2. The Project plastic Box does seem to have some effect - chatter changes if I raise the board from the box - capacitance ?
Is a Metal Project Box needed ?
3. Caps of 2mf across the TX Coil does Not remove the Chatter.
4. Low Pwr Voltage causes Chatter like 9V source is not enough.
5. Chatter is not immediate, starts after half minute of warmup after power on.
6. Chatter is random like: click click hiss buzzz click buzzz hisspause ... ,
but once in the while comes out like a constant beat of buzzes - buzzz pause buzzz pause buzzz ...Comment
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Just a thought....
My apologies, Iam sort of butting in here, I do not have an IDX-Pro machine....Originally posted by ampirate View Post
Is it possible to change from possibly 4 wires in a single shielded cable, to 2 x 2 wires in two shielded cables and test the difference, WITHOUT MAKING ANY OTHER CHANGES? Maybe that will help to quieten things down?
Also connecting shields only once at the electronics end, not twice (at both ends for example).....
As the shields may touch IN the search head, then both should be connected only once to the same shield I feel, no ground loops, though the next time I make a coil (IGSL), I will make sure that the coil shields do not touch and connect each one to the same shield as the coil its feeding.....next winter I expect, once I have made the "Davor" changes as well.....
Just a thought, what happens if the coil shields are "cross" connected.....I would expect problems, but am I right!!!
Regards
Andy.
PS. All wires separately shielded?Comment
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I am saying TX should be shielded isolated from RX, otherwise there wil be crosstalk - I assume.
That is my point - I think it should be (2) Shielded Cables - one shielded cable for TX pair , and one shielded casble for RX pair.Comment
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The Tesoro Bandito I just bought uses a cable with 2 conductors and sheild and another 2 conductors and shield but
the shields are touching in the cable and they use the sheilds for one side of the TX thus the RX has the TX energy
all around it! It seems they should have used 2 sheilded conductors for TX and 2 for RX and a seperate chassis ground
for the shield....Comment
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I think the Shields can Touch - without any problem - because they are bothy still tied to GND.
But, I think there needs to be a Shield Between the TX and RX signal Wires.
I have the RX Wires Shielded, but the TX Wires Cable are not.Comment
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I feel the same way as you.
AndyComment
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Well, I shielded the Coil, besides the Cable.
Board Shield Pin -to- Cable shield -to- Coil Shield.
But its still Chattering like Morse code: beep beeeppp beep beep beeeep ...Comment
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With the wire thing and sheilds, yes it makes great engineering sense to split the Tx and Rx wires up. But alas lots of people have made usb2 wire work ok...
The belden cable mentioned in early IGSL posts had 2 pair screened - twice. and was pretty good.
NEL and ML , sunray etc use 2 coaxes, the braids dont touch along the length of the wire.
The amount of coupling you get from the cable is offset by the coupling in the coil and can sum to a few mV.
I read you have 1V pp on preamp output --- this could be lower, if you move one coil relative to the other in the housing.
Your phasing is key to success also - without 2CH scope you need to arrange to reject ferrite... Have you tried this.
You 9V battery is non standard for these builds ---- Get it up to 12V.
Try thin mic coax on the geb pot, --- keep pot leads short, a sprawling mess is most likely to cause problems.
Dont use the small sounder from the kit, as they are not great, use a speaker of earbuds
You may be picking up some other equipment noise, from your house, (long shot)
did you build a kit off silverdog? or is it your own build/pcb
Post some decent images with good resolution/focus so we canread the values etc and we may spot a silly.
If you reomve the coil wires totally - it should be silent, No Tx, no Rx - does it still osillate like this?
Is your TxRx coils over something close to metal.
Did you fit the diode feedback on the geb filter/amp -- is it the right way / did you go for a zener?
you you scope the oscillatio/chirp on the filteramp output before the comparator input. If its 125ms period it is the filter amps oscillating. (As about 70dB of gain there)
keep trying they do pull some things in... like this...
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