Geotech Baracuda optimal tunning

[surfdetector]

Many thanks for the link to the Whites video and the Timing jpg, these will help me greatly in my understanding.
Cheers

[ionut_mtb]

[ATTACH]49352[/ATTACH]

I appreciate your patience. I have redone the shot triggered properly this time I hope. I have a lack of understanding about where the two signals need to be optimally in relation to each other. Does the channel 1 signal need to slide more to the left? (I am counting on the old adage that one is never too old to learn)
Cheers

Hello. I found this picture in my computer, i think is russian but you will understand. delay sample is adjustable from the potentiometer and it should end around 10-20us after the pulse width. (depending on the coil quality) after the delay you have first sample(pin3) 40us, distance between 1st and 2nd sample (pin11) 140us and second sample (pin4) 40us.


https://www.youtube.com/watch?v=zwGBZhRCLFI&t=356s
this video made me understand how pi works 5years ago.

oh sorry, now i saw that you are talking about baracuda, not surf pi. but it should be the same..

https://www.geotech1.com/forums/show...roject-Details

hello. you will find the timings in the building document. your 1st sample starts somewhere at 15us. it is ok,

[surfdetector]

I appreciate your patience. I have redone the shot triggered properly this time I hope. I have a lack of understanding about where the two signals need to be optimally in relation to each other. Does the channel 1 signal need to slide more to the left? (I am counting on the old adage that one is never too old to learn)
Cheers

[Qiaozhi]

[ATTACH]49349[/ATTACH]

I have attached a shot showing U4 pin10 and U2 pin6 on my pcb and as I am an electronics novice, I would like to know if this approximates what is being stated by Qiaozhi?
Cheers.

Almost correct, but you've triggered the scope on channel 2 instead of channel 1.
However, your image still shows the relationship between the main sample delay and the preamp output.

[surfdetector]

The best way to set the sample delay is to monitor the delay pulse at U4 pin10 on channel 1 of the scope, and the preamp output at U2 pin6 on channel 2. Trigger the scope from channel 1 using the rising edge. Then set the external delay pot to zero, and adjust the delay trimmer to position the start of the sample pulse between the point where the preamp output comes out of saturation and when it gets close to the 0V line. There is no advantage to sampling before the point where the preamp comes out of saturation.

I have attached a shot showing U4 pin10 and U2 pin6 on my pcb and as I am an electronics novice, I would like to know if this approximates what is being stated by Qiaozhi?
Cheers.

[Qiaozhi]

this is the way i set it on pin 6 u4 i set the pot to 0 and adjusted the trimmer to the point before it flat tops this seems to be the best setting for the delay
[ATTACH]39668[/ATTACH]

This is a consequence of the simplistic way that the Barcuda generates delays using a 40106. The sample pulses are not nice square waves.

and when it set you turn the pot to max resistance you get
[ATTACH]39669[/ATTACH]
i would say that's optimal for my coil im using, or am i setting the delay wrong or is there a better way ?

The best way to set the sample delay is to monitor the delay pulse at U4 pin10 on channel 1 of the scope, and the preamp output at U2 pin6 on channel 2. Trigger the scope from channel 1 using the rising edge. Then set the external delay pot to zero, and adjust the delay trimmer to position the start of the sample pulse between the point where the preamp output comes out of saturation and when it gets close to the 0V line. There is no advantage to sampling before the point where the preamp comes out of saturation.

[homefire]

Sounds like you doing it right to me. The Rising Edges are your time marks. Using the Test Point I described measures Absolute Delay including Propagation times of the Fet's.

I used the Old Schematic showing points for Chn 2 at 4066. On New schematic it would be just after the Fet's.


STEP 6
Sample Pulse Generator (see Fig. :
Fit R14 (20k cermet), R15 (15k), R17 (150k), R21 (12k), C7, C12, C13, C14 (4n7), PL2 (10k
Sample Delay Pot).
Monitor the TX oscillator using an oscilloscope at U4 (pin 4) using channel 1, and main sample
delay U4 (pin6) using channel 2. Trigger off channel 1. Short pin2 of PL2 to either pin 1 or pin 3 (or
use 10k sample delay pot adjusted to minimum resistance setting) and adjust R14 for a minimum
sample delay of 20us. The final minimum sample delay will depend on the coil you've constructed,
but 20us will be ok for initial setting up. If no oscilloscope is available, then build the sampling
integrator in Step 7 before adjusting R14.

[kosacid]

this is the way i set it on pin 6 u4 i set the pot to 0 and adjusted the trimmer to the point before it flat tops this seems to be the best setting for the delay

and when it set you turn the pot to max resistance you get

i would say that's optimal for my coil im using, or am i setting the delay wrong or is there a better way ?

[homefire]

You wanted Optimal. Optimal for Me in a PI is short as possible sample delay. I seek Low Conductive targets like Gold. You may want Longer Delays to be Optimal for what your looking for. The Three point I referenced are the point you would need to measure to include All Delay after Tx Shut Off

[kt315]

optimal you meant the depth or what? what you want? bara works with fixed PULSE WIDTH 50 us, no possibility to grow the depth.
DELTA PULSE works with variable PULSE WIDTH from 150 to 500us. DELTA PULSE has optimal PULSE WIDTH if
you meant pulse width.

[kosacid]

the timings is there but no details i already looked at that @homefire that's the points i was testing but i used the opamps output, all i was looking for on this thread was a quick setup for people who own scopes and some details and info lol, mines is already setup and working fine i just think this info is missing

[Koala]

Nope just by main sample delay within the range of adjustment.


Timings are in the build document.
http://www.geotech1.com/forums/showt...roject-Details

[ionut_mtb]

http://www.geotech1.com/forums/attac...0&d=1459631333



By adjusting the delay Can get nearly 14" on the gold ring but then the fibula is down to 3"


Coil is just solid enamelled copper. Post specs on here but can't seem to find the post

Adjusting the lenght of the pulse delay?

[homefire]

Here if you want absolute Delay Measures including Propagation delay. Chn 1 end of Tx is the start in time. Chn 2 first and second sample time.

[kt315]

http://www.geotech1.com/forums/forum...Published-2015

good starting book to begin a way into electronics. ITMD. believe me now.