Geotech Baracuda optimal tunning

[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.

[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]

[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]

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

[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]

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