Replies to Minipulse Plus

[Qiaozhi]

Well analysed surfdetector yes it is. I disconected the coil to avoid a maximum of interf?rences. By the way my buzzer ring with or whithout coil when audio treshold is superior to -1.3V.

Are you sure you have the connections correct on the coil connector?

[Albdelafar]

Well analysed surfdetector yes it is. I disconected the coil to avoid a maximum of interf?rences. By the way my buzzer ring with or whithout coil when audio treshold is superior to -1.3V.

[surfdetector]

On the first screenshot I have the main sample delay (TP6) put to is maximum (44us) on CH1 and TX pulse (TP2) set to 340us on CH2.TX pulse period was set to 9ms.
You can see here CH1 to TP2 and CH2 to TP3.

From the image of your preamp output TP3, it does not seem like you have a coil attached.

[Albdelafar]

On the first screenshot I have the main sample delay (TP6) put to is maximum (44us) on CH1 and TX pulse (TP2) set to 340us on CH2.TX pulse period was set to 9ms.
You can see here CH1 to TP2 and CH2 to TP3.

[Qiaozhi]

There it is all samples measurements !! to my mind all is right.
[ATTACH]54729[/ATTACH]
[ATTACH]54730[/ATTACH]
[ATTACH]54727[/ATTACH]
[ATTACH]54728[/ATTACH]

Things mostly seem to be correct, except that the TX pulse width is only 44us, whereas the suggested pulse width in the Build Document is 400us.
Your TX pulse rate is also slightly lower than the suggested 125pps.

Can you also post an image of the preamp output?
Set CH1 = TX OSC (TP2)
and CH2 = preamp output (TP3)

[Albdelafar]

There it is all samples measurements !! to my mind all is right.

[Albdelafar]

Hi Tibuck19,
I don't think this is my issue because power is from an 4s2p accu with a tension regulator put to 12V.
To George,
ok no problem i will put pictures of sample timing asap.

[Tibuck19]

Could this issue be cause by the power? are you using a bench top power supply or batteries? i have one of those cheap no good china made bench power supply, and i can not use it when assembling and testing MD kits i get all kinds of ringing and odd behavior, however when i use actual batteries the detectors are fine. Actually if im not maskaken Qiaozhi was the one that had suggested that solution to me a while ago.

[Qiaozhi]

Yes it is. There is no problem on step 8 treshold pot voltage is between -3.9 and +4,1.
So do you have an Idea on what could be wrong on audio stage ? Capacitor I used are polypropyl?ne and resistor are 1% 0,5w all tested before soldering to pcb.

It's very difficult to debug a design remotely. Maybe it's not actually a problem in the audio stage.
Have you checked that the main sample and EFE samples are in the correct positions and the same width?
Can we see scope images at each stage?

[Albdelafar]

Yes it is. There is no problem on step 8 treshold pot voltage is between -3.9 and +4,1.
So do you have an Idea on what could be wrong on audio stage ? Capacitor I used are polypropyl?ne and resistor are 1% 0,5w all tested before soldering to pcb.

[Qiaozhi]

Thank you very much for the reply !! It is my second board of minipulse rev_e and I have the same problem on both but higer on this one who is the second that i build to do experiments on diff?rent pre amps. All steps are good until step 8 or I find -4 and +4v and variation when a taget is near the coil. So I suppose that my issue is on the audio stage am I right ?
Thank for the support !!

I took measurement on my oscope with audio treshold low enought to cancel buzzer to ring. The second was took when it start to ring continously. All this experiment was made without coil CH1 on TP1 and CH2 on speaker positive.
[ATTACH]54720[/ATTACH]
[ATTACH]54721[/ATTACH]

If the DC voltage at TP1 can be varied by the Threshold pot between +/- 4V, then the problem does appear to be in the audio stage.

[Albdelafar]

I took measurement on my oscope with audio treshold low enought to cancel buzzer to ring. The second was took when it start to ring continously. All this experiment was made without coil CH1 on TP1 and CH2 on speaker positive.

[Albdelafar]

Thank you very much for the reply !! It is my second board of minipulse rev_e and I have the same problem on both but higer on this one who is the second that i build to do experiments on diff?rent pre amps. All steps are good until step 8 or I find -4 and +4v and variation when a taget is near the coil. So I suppose that my issue is on the audio stage am I right ?
Thank for the support !!

[Qiaozhi]

can anyone confirm that this situation is abnormal ?! The detector works but because of these audio threshold settings my detection depth is really poor.

This is not normal.
I suggest going through all the checks at each step of the build process to identify the fault.

[Albdelafar]

can anyone confirm that this situation is abnormal ?! The detector works but because of these audio threshold settings my detection depth is really poor.