PI Audio

[h9361]

Here is a great little VCO circuit Mickstv posted back 2-3 years ago and I've had veroboard version for use on my bench for so long..it finally gave out so I decided to put it onto a PCB.
I added extra decoupling, changed Fet and added option for audio amp connection..all vanilla stuff.

Had 10 Blank PCBs made by PCBway for $25 Au and $20 of that was delivery.. Thanks for the heads up on that Moodz.

I normally use a digital audio version of this but sometimes analog is a better fit and Mick's circuit was worthy of a pcb
It is SMD using mainly 0805 parts.

[ATTACH]45385[/ATTACH]

The original circuit is posted in the Minipulse Audio section..

Cheers
Mdtoday

Hello
Dear Mdtoday
I have a request, i hope you accept it.
Is it possible to take a test video from your audio part?
Thanks

[h9361]

As mickstv said, attempting to discriminate on a PI using target conductivity is a fruitless task.

Hello
Dear Qiaozhi.
Please forgive me for my question.
Have you ever received any report for best damping value of 320-350uh coil (Hammerhead)?
Thanks.

[surfdetector]

Hello
Dear Qiaozhi.
Please forgive me for my question.
Have you ever received any report for best damping value of 320-350uh coil (Hammerhead)?
Thanks.

You can easily find this by using a damping resistor jig as in this video:
https://youtu.be/Gr__N4_k2Mc

[h9361]

You can easily find this by using a damping resistor jig as in this video:
https://youtu.be/Gr__N4_k2Mc

Thanks dear surfdetector.
I enjoyed from it.

[h9361]

Measured with input zero it is 400hz, just change to suit your requirement

Hello
Dear Mdtoday
Can you tell me value of VR1-Pot in your schematic?
Thanks.

[Mdtoday]

Hello
Dear Mdtoday
Can you tell me value of VR1-Pot in your schematic?
Thanks.[ATTACH]55332[/ATTACH]

VR1=100k and C8 = 2.2uF

[h9361]

VR1=100k and C8 = 2.2uF

Thanks for your helping.

[h9361]

You can easily find this by using a damping resistor jig as in this video:
https://youtu.be/Gr__N4_k2Mc

Hello
Dear Surfdetector.
Please see the attached, it's HH1 audio part. Do you think it's correct or has error?!
Thank you

[mickstv]

Hello
Dear Surfdetector.
Please see the attached, it's HH1 audio part. Do you think it's correct or has error?!
Thank you
[ATTACH]55362[/ATTACH]

Once again this has nothing to do with the thread. You need to post in the HH1 part of the forum.

This is off topic....

[h9361]

Once again this has nothing to do with the thread. You need to post in the HH1 part of the forum.

This is off topic....

OK, thank you

[h9361]

VR1=100k and C8 = 2.2uF

Hello
Dear Mdtoday.
I want to make your Audio + Mr. Walter's audio + HH1 audio and to compare them.
As you remember, i'm trying to build your schematic based dip method, not SMD.
Mr. Walter helped me (i really thank him) how to add a LM386 to your schematic (attached). Off course, he pointed that i need to build and test.
Anyway, is it possible to tell me your suggestion for adding LM386?
Thanks.

[Mdtoday]

Hello
Dear Mdtoday.
I want to make your Audio + Mr. Walter's audio + HH1 audio and to compare them.
As you remember, i'm trying to build your schematic based dip method, not SMD.
Mr. Walter helped me (i really thank him) how to add a LM386 to your schematic (attached). Off course, he pointed that i need to build and test.
Anyway, is it possible to tell me your suggestion for adding LM386?
Thanks.
[ATTACH]55366[/ATTACH]

Looks ok, now go build it and try it out, build the power supply and audio amp first, make sure it works, then add Mickstv circuit, do it in stages, test each stage then move to next one. Dom44 did a through hole version, others have built that one too, he used an Lm386.
As Mickstv and others have said, the circuit works, so why not build as per the schematic posted first, give it a try then start changing things.
It is the best way to start, try not to complicate things, I’m sure you will do just fine.

[h9361]

Looks ok, now go build it and try it out, build the power supply and audio amp first, make sure it works, then add Mickstv circuit, do it in stages, test each stage then move to next one. Dom44 did a through hole version, others have built that one too, he used an Lm386.
As Mickstv and others have said, the circuit works, so why not build as per the schematic posted first, give it a try then start changing things.
It is the best way to start, try not to complicate things, I’m sure you will do just fine.

thanks dear Mdtoday.
I saw Dom44's PCB. He used the attached schematic, do you think it's true? Off course, i think he labeled mistakenly E and C of Q1 in his PCB.

[h9361]

No pin1 of IC8a. Forget about the HH sat, the rest of the circuit has a manual threshold control, which is better for small target detection.

It's easier to do three samples the you only need one integrator.

S1 about 5us, S2 130us and S3 125us all approx. Then you adjust the delay between S1 and S2 to ground balance

Hello
Dear mickstv
Please see attached, it's explanation of Mr. Carl about GB process.
I think your method is completely different (U-second and formulation) than it.
Is it possible to tell me more about your method?
Thanks

[surfdetector]

Hello
Dear mickstv
Please see attached, it's explanation of Mr. Carl about GB process.
I think your method is completely different (U-second and formulation) than it.
Is it possible to tell me more about your method?
Thanks
[ATTACH]55642[/ATTACH]

@h9361
This thread is about PI Audio, you should really start a new thread if you want to begin asking about Ground Balance.