Voodoo Main Discussion

[surfdetector]

Hi George
I have notice that you have referred to TP1 as a reference point on more than one occasion. Looking at my board TP1 is not actually connected to anything else. Same on the Gerber files. Am I missing something? My board is REV-C from Silverdog

TP1 is 0 volts and is the ground point. If you test it there is continuity with the +12V @ PL11 pin 1

[MartinB]

The first thing I noticed about your images, when compared to Fig. 3-19, is that the PI preamp is inverted. The second thing I noticed is that you appear to have the scope ground connected to the negative terminal of the battery instead of the positive. TP1 should be used as the reference point.

Hi George
I have notice that you have referred to TP1 as a reference point on more than one occasion. Looking at my board TP1 is not actually connected to anything else. Same on the Gerber files. Am I missing something? My board is REV-C from Silverdog

[Altra]

no, I don't understand anything anymore ... I can't reverse the output, moreover my oscilo is showing signs of weakness, it's not my best day pff, I don't even have 0v with r30, and the curve s reverse. it's a mess

I don't know any details about this project, but it appears your coil wires are reversed in some way. That's why your pre-amp output is reversed.

[lamoiz]

Is your preamp output now the correct polarity as shown in Fig. 3-19?
I don't know what's causing the beeps at the moment, but the preamp output looks clean. Let's make sure the preamp output is OK first before moving on.

no, I don't understand anything anymore ... I can't reverse the output, moreover my oscilo is showing signs of weakness, it's not my best day pff, I don't even have 0v with r30, and the curve s reverse. it's a mess

[Qiaozhi]

I did the invertions on the jumpers. actually I made all the measurements with the mass of the oscilo on the positive .. oops.
Regarding the beeps beeps between the targets, I noticed that if the threshold is at 20, the beeps disappear almost completely, what does that mean?

Is your preamp output now the correct polarity as shown in Fig. 3-19?
I don't know what's causing the beeps at the moment, but the preamp output looks clean. Let's make sure the preamp output is OK first before moving on.

[green]

Just wanted to add ,
A unforeseen benefit to this coil arrangement is very little coil edge sensitivity.
A beer can has to be within 4 inches to respond.

This may really help for target separation in a small version of the coil.

Be Well

Interesting your coil has low edge sensitivity. My figure8 coil detects almost the same edge distance as centered over one of the Rx coils. Coke can, Rx_(2)133mmID fig8. 24inches centered over one coil, 22inches from the side(same plane). Probably not good.

[lamoiz]

The first thing I noticed about your images, when compared to Fig. 3-19, is that the PI preamp is inverted. The second thing I noticed is that you appear to have the scope ground connected to the negative terminal of the battery instead of the positive. TP1 should be used as the reference point.

I did the invertions on the jumpers. actually I made all the measurements with the mass of the oscilo on the positive .. oops.
Regarding the beeps beeps between the targets, I noticed that if the threshold is at 20, the beeps disappear almost completely, what does that mean?

[Qiaozhi]

tp3 tp10 [ATTACH]53825[/ATTACH] et
another scale [ATTACH]53826[/ATTACH]we can see changes in the amplitude of the two signals, simultaneously .. what does this mean?
[ATTACH]53827[/ATTACH]

The first thing I noticed about your images, when compared to Fig. 3-19, is that the PI preamp is inverted. The second thing I noticed is that you appear to have the scope ground connected to the negative terminal of the battery instead of the positive. TP1 should be used as the reference point.

[lamoiz]

tp3 tp10 et
another scale we can see changes in the amplitude of the two signals, simultaneously .. what does this mean?

[Qiaozhi]

[ATTACH]53824[/ATTACH]

This one might be better

That looks good.
I've removed your erroneous attachment in post #478. I guess you didn't really want anyone seeing that.

[surfdetector]

TP10 versus TP3



This one might be better

[lamoiz]

Fig. 3-19 shows TP10 and TP3 (not TP11).
What you're showing is the DISC preamp output versus the main sample pulse (and that doesn't look correct anyway).

Can you show the PI preamp output versus the main sample pulse?

indeed I had to put the wrong photo ..oupss and obviously, Surf also made a file error !!! well I'll take a photo tomorrow ..tp3 tp10.

[surfdetector]

Fig. 3-19 shows TP10 and TP3 (not TP11).
What you're showing is the DISC preamp output versus the main sample pulse (and that doesn't look correct anyway).

Can you show the PI preamp output versus the main sample pulse?

[Removed erroneous attachment]

Just for comparison purposes I have attached the PI pre-amp output versus the main sample pulse from my machine.

[Qiaozhi]

fig 3-19 tp3 tp 11 what do you think?
[ATTACH]53813[/ATTACH]

Fig. 3-19 shows TP10 and TP3 (not TP11).
What you're showing is the DISC preamp output versus the main sample pulse (and that doesn't look correct anyway).

Can you show the PI preamp output versus the main sample pulse?

[lamoiz]

test carried out, outside ... device still beeps beeps beeps non stop