Dumping resistor heating

[kt315]

ok. TX pulse is 30uS - so decrease PULSE WIDTH to 30us. do first step.
second step use 1mH coil.

or then be back to NORMAL for surf pi frequency - 600Hz.


whites engineers so crazy idiotics... they could not set pps to 10000. SO NAIVE PEOPLE!
i can! i learned in Preston university on cathedra ELECTRONICS!

[kt315]

DO NOT MIX OLD GOLDQUEST AND NEW GOLDQUEST SS IN ONE PILE.
ITS ABSOLUTELY DIFFERENT MODELS.
ANOTHERWAY WE GET ONLY MESS.

schematic of GQ SS is same as CS6PI. no differencies there.
Eric uses marketing way using GS name. this is only his right.

[ionut_mtb]

Did some research on the forum and found some old post regarding GQ coil. It looks like goldquest has 300-350uh with 30awg(0.25mm) wire.

[ionut_mtb]

https://www.findmall.com/read.php?34...569#msg-887569

Hi Dwt,

The CS6PI is similar circuitry to the Beachscan, both of which were made some years ago now. A later development is the Goldquest which has also gone through two or three versions.The major changes since the CS6PI is the ability to sample at 10uS, the addition of a variable SAT control, and a switchable two stage autotune filter, plus you can use DD coils for all but highly mineralised ground. What you need therefore is the addition of ground balancing to the latest Goldquest system. Hmmm!

See the latest Goldquest SS v3 details by clicking on the Surfscanner banner above.

thanks KT, i will check your link. I know goldquest is very sensitive to small gold, i don't try to replicate that, i'm interested only in depth of gold rings. Coil inductance is not critical, i will try to add some series resistor to see the result.

[ionut_mtb]

Try another electrolytic capacitor, with a capacity of 1200μF

I use 3300uf.

[ionut_mtb]

ionut_mtb, I am curious is that text from a post made by Eric Foster, or your own experiment ?

Post #40

http://www.geotech1.com/forums/showthread.php?23351-PI-limit-to-early-sampling/page2&highlight=Prompted+development

[6666]

"Your post prompted me to get out a development model of the Goldquest SS and run it up on a scope. This will run at a minimum delay of 8uS from the TXoff initiation. TX pulse is 30uS wide and 13K PPS. The coil is a tapped mono of 450uH total but with a tap at 150uH. The TX drives the tap and the RX connects to the whole coil. The TX Mosfet is a IRFD210 with 27R in series with the drain ON resistance, and with the R of the coil we have about 0.3A pulse current. The rise time is 8.8uS so the pulse is substantially flat top for over 20uS and at switch off there is no avalanche.

ionut_mtb, I am curious is that text from a post made by Eric Foster, or your own experiment ?

[kt315]

cs6pi coil

[kt315]

https://www.findmall.com/read.php?34,880135,887569#msg-887569

Hi Dwt,

The CS6PI is similar circuitry to the Beachscan, both of which were made some years ago now. A later development is the Goldquest which has also gone through two or three versions.The major changes since the CS6PI is the ability to sample at 10uS, the addition of a variable SAT control, and a switchable two stage autotune filter, plus you can use DD coils for all but highly mineralised ground. What you need therefore is the addition of ground balancing to the latest Goldquest system. Hmmm!

See the latest Goldquest SS v3 details by clicking on the Surfscanner banner above.

[kt315]

dip4

[Andi68]

Try another electrolytic capacitor, with a capacity of 1200μF

[kt315]

you killed three rubbits by one shot.
-----------------10ohmcoil----
Beachscan

Posted by: Eric Foster(---.ipt.aol.com)
Date: April 6, 200004:35PM

This is an example of aPI detector that breaks with traditional principles to some degree. Instead ofpulsing a high current through a low resistance and low inductance coil itpulses only 0.2A peak through a 10 ohm coil that has an additional 39 ohms inseries. The coil also has an inductance of over three times the usual amountbut we are still able to sample at the magic 15uS for use on a wet beach. TheMosFet can be a small one with a relatively low voltage rating and the mean dccurrent taken from the batteries is only 65mA giving good life from 8AA cells.
Eric.

[ionut_mtb]

"Your post prompted me to get out a development model of the Goldquest SS and run it up on a scope. This will run at a minimum delay of 8uS from the TXoff initiation. TX pulse is 30uS wide and 13K PPS. The coil is a tapped mono of 450uH total but with a tap at 150uH. The TX drives the tap and the RX connects to the whole coil. The TX Mosfet is a IRFD210 with 27R in series with the drain ON resistance, and with the R of the coil we have about 0.3A pulse current. The rise time is 8.8uS so the pulse is substantially flat top for over 20uS and at switch off there is no avalanche.

The original GQ SS ceased production about 5 years ago but that used a standard 300uH mono and the minimum delay was 10uS with 10K PPS. EF"

This is only an experiment, which perform better than original surf pi, and is P channel mossfet, not N channel like Eric Foster uses in his detectors. I don't know schematic of Goldquest SS, it might have series resistor. Setting up good a PI detector require theoretical knowledge that i don't possess.

[kt315]

Eric Foster: My Beachscan uses a coil of 1mH as does the C.Scope CS7 and CS6PI.

[kt315]

I don't know why the photos are upside down, in my phone are normal.
Kt i don't understand what you mean. Pps is high, not sure exactly, i was aiming 10000pps like goldquest ss, but my tx pulse is 60us not 40.

you want to kill two rubbits but you forgot that Eric did NOT make a detector with 10000pps on 300uH coil.
goldquest ss working with 1mH (MILLI-) coil. and plus there is a resistor in serial on board.
so there is NOTHING of the heat and Eric uses 4pin dip mosfet with 0.8A current.