Superscan PI

[nasios]

Hi Nasios,

can you post the schematic of your PCB board? Then it would be easier for people to give you an answer to your questions.

Hello GeoMax, I don’t have the schematic, but now that I’m looking at the PCB and Eduardo1979’s schematic, I can see that they are identical.
is 0V messure in Pin 3? with 10K pot

[eduardo1979]

Hi Nasios.
You need to measure at PIN 6 of the TL061. You should have a negative voltage with respect to GND. Connect the negative probe of your multimeter to GND (V+) and the positive probe to PIN 6. You should measure a negative voltage of approximately -4.0V to -4.5V. Remember to hold down the detector's RESET button while taking this measurement. The detector coil doesn't need to be connected. This adjustment is crucial because this circuit acts as an active clamp, controlling the opening and closing of the J113 JFETs. Be very careful with the JFETs; they must be of good quality, not counterfeit, as well as the detector's integrated circuits. I recommend testing the detector with a small coil until you learn how to make all the adjustments correctly, and then you can try larger coils. If after all the adjustments you still can't get the detector to work correctly, I recommend adding a potentiometer to adjust the offset of the NE5534 preamplifier, just like on the GS5 Lite. Check the -12V, -5V, and +5V voltages. I also recommend checking the waveform at the 5534 output to make sure the damping resistor value is correct. Also check the outputs of the 4538 and 555 timers to see if the synchronization times and detector frequency are correct. Anyway... follow these steps and then we'll see what happens.

[GeoMax]

Hello GeoMax, I don’t have the schematic, but now that I’m looking at the PCB and Eduardo1979’s schematic, I can see that they are identical.
is 0V messure in Pin 3? with 10K pot

Hi Nasios,

thanks for the clarification.

[nasios]

Hi Nasios.
You need to measure at PIN 6 of the TL061. You should have a negative voltage with respect to GND. Connect the negative probe of your multimeter to GND (V+) and the positive probe to PIN 6. You should measure a negative voltage of approximately -4.0V to -4.5V. Remember to hold down the detector's RESET button while taking this measurement. The detector coil doesn't need to be connected. This adjustment is crucial because this circuit acts as an active clamp, controlling the opening and closing of the J113 JFETs. Be very careful with the JFETs; they must be of good quality, not counterfeit, as well as the detector's integrated circuits. I recommend testing the detector with a small coil until you learn how to make all the adjustments correctly, and then you can try larger coils. If after all the adjustments you still can't get the detector to work correctly, I recommend adding a potentiometer to adjust the offset of the NE5534 preamplifier, just like on the GS5 Lite. Check the -12V, -5V, and +5V voltages. I also recommend checking the waveform at the 5534 output to make sure the damping resistor value is correct. Also check the outputs of the 4538 and 555 timers to see if the synchronization times and detector frequency are correct. Anyway... follow these steps and then we'll see what happens.

Hello eduardo1979,
I measured pin 6 of the TL061 and it has 4.35 volts.
I measured the 7912: output = -12 V.
The 7905: output = -5 V.
The 7805: all three pins measure 22 V.

ok i find 3904 3906 have problem, i change now all ok have sound, tomorrow i will build coil.

[eduardo1979]

I'm glad everything is going well!
The voltage on pin 6 must be negative (-4.35V), be careful with that! It cannot be positive.

[GeoMax]

Hi Eduardo1979,

I have the following question regarding your RosPi design: Why did you use four different IC types in the middle section (U6, 7, 8, 9)? Is there a specific reason for this? I would, for example, only use three TL072s there.

[eduardo1979]

Hi Eduardo1979,

I have the following question regarding your RosPi design: Why did you use four different IC types in the middle section (U6, 7, 8, 9)? Is there a specific reason for this? I would, for example, only use three TL072s there.

Hi Geomax.
There is no specific reason, and I feel the same way you do. I simply drew the schematic based on the original PCB, which had been posted on the forum long before I started drafting the schematic myself. Since no schematic was available, I decided to draw one that matched the PCB layout, as I don't like building a detector blindly without understanding how the circuit works. That is simply why I decided to draw it. Furthermore, this circuit has plenty of room for improvement—especially the sampling integrator circuit, as well as the audio amplifier and VCO. I would also opt to add a unity-gain inverting amplifier after the preamplifier, remove the differential integrator, and replace it with a single-ended integrator. There are many things about this circuit that could be improved.

[GeoMax]

Hi Geomax.
There is no specific reason, and I feel the same way you do. I simply drew the schematic based on the original PCB, which had been posted on the forum long before I started drafting the schematic myself. Since no schematic was available, I decided to draw one that matched the PCB layout, as I don't like building a detector blindly without understanding how the circuit works. That is simply why I decided to draw it. Furthermore, this circuit has plenty of room for improvement—especially the sampling integrator circuit, as well as the audio amplifier and VCO. I would also opt to add a unity-gain inverting amplifier after the preamplifier, remove the differential integrator, and replace it with a single-ended integrator. There are many things about this circuit that could be improved.

Hello Eduardo1979,

I agree with your comments. I, also would only start a PCB project if I had a schematic for it. However, since most free PCBs from the internet often contain errors, I prefer to create them myself. That way, I know for sure that they correspond to the schematic. And yes, the circuit has potential for improvement. But if you improve it too much, it's no longer the original circuit. If you want to improve every circuit stage, it's better to create a new design from scratch.

[nasios]

I'm glad everything is going well!
The voltage on pin 6 must be negative (-4.35V), be careful with that! It cannot be positive.

Hi eduardo1979, i check the pin 6 from U1 555 253HZ and osc have this and U3, U4 4538 pin 6,7,9,70 have the osc 269Hz, and my pcb rospy have UA709 not the NE5534

[ZOUjiarui]

It's a waste of effort. I don't know what secrets it has. The voltage is normal, 90Hz, and it can only be adjusted to half the normal pulse sensitivity at most. It's really useless.

[Goggy]

Hello all,

I am new to the forum, although experienced in the Superscan. How closely is this project board based upon the original Superscan?

I may be able to advise on some of the issues if closely enough related? Kind regards.