Superscan PI

[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 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]

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.

[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.

[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.

[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.

[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

[GeoMax]

Hello , i build this

• Technology
• Schematics

my personal colection

post #3

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.

[nasios]

Hello
I built the detector from post #294, and it worked perfectly. I don't know which version you built.

eduardo1979,On the TL061, what voltage should I measure on pin 3? The potentiometer is connected there, so what exactly should I adjust it to?

[nasios]

Hello
I built the detector from post #294, and it worked perfectly. I don't know which version you built.

Hello , i build this

• Technology
• Schematics

my personal colection

post #3

[eduardo1979]

Hello eduardo1979, i finish the project (i don't remember if you build the same) and all time led is open and speaker don't out noise , coil 510uh 1.9ohm , what can i messure volt out is all ok

Hello
I built the detector from post #294, and it worked perfectly. I don't know which version you built.

[nasios]

Hello eduardo1979, i finish the project (i don't remember if you build the same) and all time led is open and speaker don't out noise , coil 510uh 1.9ohm , what can i messure volt out is all ok

[ZOUjiarui]

I retested the coil waveform: 1. Under no-load conditions. 2. The damping resistor was increased from 150Ω to 300Ω. (Figure 3 shows the waveform at 150Ω without any modifications.) I suspected the problem was with the coil, but after changing the damping resistor, an extra straight line appeared in the waveform.

[ZOUjiarui]

The frequency and pulse width displayed on the oscilloscope waveform may be incorrect when manually adjusted; they only display correctly when automatically adjusted.

[ZOUjiarui]

我重新测试了线圈波形：1. 空载条件下。2. 阻尼电阻从 150Ω 增加到 300Ω。（图 3 显示的是 150Ω 时的波形，未做任何修改。）我怀疑问题出在线圈上，但更换阻尼电阻后，波形中出现了一条额外的直线。