Surf PI Pro

[getsa]

In this thread there are PI projects, and it would be reasonable they to be moved to the intentionally created PI projects branch...?

[Carl-NC]

Unfortunately people often post things in an existing thread when a new thread would be appropriate. It's a lot of work to split a thread up and I just don't have the time so the best I can suggest is to start a new thread if you want to steer the topic somewhere else.

[Rollin_sb]

Thanks for the help. Parts are on order. I'm sure I'll have many questions.

-Rollin_sb

[Rollin_sb]

What are the best modifications for the Surf PI Pro?

[Vadim18]

What are the best modifications for the Surf PI Pro?

I dont know what type of modification may be best for you but I made and tested last year Surf PI with extended dynamic range modification. That modification allowed me to locate big targets like in pinpoint mode and small targets near big ones.

[GeoMax]

Hi Vadim18,

what kind of extended dynamic range modification have you made to the Surf Pi?


GeoMax

[Vadim18]

Hi GeoMax
From first amplifier to demodulator and dc amplifer Surf PI has fixed gain but i tried and succesfully changed that gain to variable, another words that is same automatic gain control i.e. AGC.
AGC keeps first amplifier from saturation, so i can come close to big target and locate border of that target not from half meter around it but much more closer.
I tested that modification last year outumn, work fine and without glitches.
From table tests i can put 1,5 AA battery to centre of my coil and than still be able to detect coins.

[GeoMax]

Hi Vadim18,
Thanks for your explanations. You say you add AGC circuits to the Surf Pi. Have you used an AGC circuit like seen in the Delta Pulse detector and have you modified the sampling circuit accordingly to fit the AGC of the Delta Pulse circuit? Moreover, for the integrator have you used a similar circuit as seen in the front-end of the Delta Pulse or have you actively changed the gain (resistors) in the integrator circuit part?
GeoMax

[Vadim18]

Hi Vadim18,
Thanks for your explanations. You say you add AGC circuits to the Surf Pi. Have you used an AGC circuit like seen in the Delta Pulse detector and have you modified the sampling circuit accordingly to fit the AGC of the Delta Pulse circuit? Moreover, for the integrator have you used a similar circuit as seen in the front-end of the Delta Pulse or have you actively changed the gain (resistors) in the integrator circuit part?
GeoMax

Hi GeoMax
All i know there is no AGC In DP, there is only zero bias correction circuit for front end amplifier and slow motion autotraking circuit for dc output. Gain in DP is tuned by gain control resistor. Nothing like that, i just used same principle like in any classic Automatic Gain Control circuit.

[GeoMax]

Hi Vadim18

Thanks for your reply. Actually, you are right. There is no AGC in the DP. The circuit in the front-end amplifier of the
DP is more or less an automatic DC offset correction circuit. After your comments, I had a closer look at the “classic AGC circuits”.
In an AGC circuit, the gain changes and not the offset of an amplifier. I do not know which AGC circuit you are using in your
Surf PI, but a Widlar current source circuit connected after the integrator of the Surf PI would do a similar job. A very similar
circuit part you see in the HH before the VCO.

Attached is my first idea of an AGC circuit for the Surf PI. Maybe you can share your AGC solution to the Surf PI as well.



GeoMax

[Vadim18]

Hі GeoMax
I have feelings that this circuit will produce oscillations, or just act like comparator becouse "+" on opamp output converts to "-" on j310 drain and than "-" goes to invertion input of opamp and in final you will get inverted "-" or positive feadback. Just avoid positive feadbacks. I already post my active calmp idea last year, that is 1/2 of AGC part.

https://www.geotech1.com/forums/showthread.php?26475-ZP-ACTIVE-DAMPING-and-NOISE-CANCELLATION&p=292733#post292733

Difference - front end amplifier must be inversion mode amplifier. This circuit can do coil damping and aditionaly can be part of AGC.

[Vadim18]

Instead of 100mA BCs transistors i recommend to use 600mA 2N4403 (pnp) and 2N4401 (npn)
Uncle Joe give us some good Disneyland equipment and some times here is a little bit noisy to make any pc or workbench work. But i think you can do it better.

[pulseinduction]

Hi all ! I want to build surf pi pro but I don't know which integrated circuits to buy. Tell me please, which integrated 5534, 4066, 4093, 555, 358, are better for surf pi pro. I have these options: NE5534AP NE5534AN NE5535P 74HCT4066 CD4066 HCF4066BEY 74HC4066 MC14066BCP HEF4066BP HCF4093BEY HEF4093BP CD4093 NE555 NE555N NE555P TLC555CP LM358N LM358AN

[Toros]

You have all the necessary elements without ICL 7660 and TL7805.
Look at the diagram of the detector and you will find your way. In other words, your question sounds like this: I want, but I have no desire!

[kt315]

try read (learn to read) datasheets on IC's. use GOOGLE. those documents give full info on every chipo. they are always in PDF format.