field test unit no 001 "model T"

[chudster]

hdphilip,

Now it is not quite like yours in some important ways ......... and neither is yours like my sims ........

Chudster

[hdphilip]

hey, wait a minute, that looks miine, ahhh, nevermind, i was on 1us per division


hold on..... postman at the door....


thanks mr postman, those are Sic's, i've been dreaming about.......


anyways back to being serious

The improvements to the adaptive damping system now damps this coil in 3 us using the new technique. I am not sure if this is a good thing.

been thinking that too......

flybacks....

Philip

[moodz]

avalanche is only dangerous for skiers LOL ....

[Davor]

Ah! So you do accelerate initial decay by large damping resistance. I like the way avalanche noise is shown on the DSO.

[moodz]

MAGIC SAUCE

....more work on the moodz frontend now sees it very close to finalisation ....

The pic below shows the input to the first amplifier and the green trace is the output from the first amplifier.

The input has been processed by the moodz patent pending ...LOL...PI frontend which damps and preps the signal for input to the first amplifier.

COIL = MONOCOIL ...18 inch standard minelab type, 280 uh, 0.4 ohm
TX RATE = 1khz
TX duration = 100us
AMP GAIN = 100X

The amplifier is a "tricked up" NE5534 ... to keep noise down whilst maintaining gain and speed.

The improvements to the adaptive damping system now damps this coil in 3 us using the new technique. I am not sure if this is a good thing.

The frontend alone can detect a 10 inch square PCB at around 50 to 70 cm .... when I feed it into the 24 bit backend ADC and processor ... well thats another story

[hdphilip]

hello moodz

the TX pulse is about a 100uS, as far as the flyback, i'll need to make a x100 probe, it's off the screen on the 'ol Tektronix scope.

philip

[moodz]

hello moodz,

i was finally able to get some time and i put into practice what chudster and i have been siming,

no, this isn't photo shop,

my scope is set at 1us per division, the bottom pulses are the 1.3 us conv for the adc converter, i still need to move them over,

i'm also usuing Cree Sic diodes throughout my circuit, still their some more work to do, but i have to put this on hold for a little until a new peice of test equipment shows up


Philip

oh, also i what to add i'm usuing about 4 feet of rg174 between my board and coil

May I enquire what the TX pulse length is, TX voltage and vertical volts / div for the flyback ? You are certainly in the ballpark for earlier sampling.

moodz

[hdphilip]

I am too busy writing patent applications

I'd rather be at the dentist..........

[moodz]

hello moodz,

i was finally able to get some time and i put into practice what chudster and i have been siming,

no, this isn't photo shop,

my scope is set at 1us per division, the bottom pulses are the 1.3 us conv for the adc converter, i still need to move them over,

i'm also usuing Cree Sic diodes throughout my circuit, still their some more work to do, but i have to put this on hold for a little until a new peice of test equipment shows up


Philip

oh, also i what to add i'm usuing about 4 feet of rg174 between my board and coil

Thats very good .... I cant confirm or deny you are on the right track for fast sampling LOL ... I am too busy writing patent applications.

moodz.

[hdphilip]

sim turns into reality!!!!!!!!

hello moodz,

i was finally able to get some time and i put into practice what chudster and i have been siming,

no, this isn't photo shop,

my scope is set at 1us per division, the bottom pulses are the 1.3 us conv for the adc converter, i still need to move them over,

i'm also usuing Cree Sic diodes throughout my circuit, still their some more work to do, but i have to put this on hold for a little until a new peice of test equipment shows up


Philip

oh, also i what to add i'm usuing about 4 feet of rg174 between my board and coil

[IBGold]

Moodz the project is only non working because the bug in the code does not allow us to program the UNI-PI if that was working we could evaluate Tinkerers design all the rest of the boards are working I will ring you.

Regards frustrated, Ian.

[moodz]

Ian ... i am looking at it in the limited time that I have .... but I have to work on working projects first and non working projects second.

Here is a thought for you ... this direct sampling project will easily do the TEM project as well ( a simple replug mod of the front end board ) so the UNIPI chip version is already obsolete.

The direct sampler will catch the whole TEM waveform so we will see then if there is any merit in it .....

and while I am at it I will add a VLF mode as well since again the signal chain is identical if all the processing is done on chip.

moodz.

[IBGold]

Looking great Moodz how is our code bug going and I still can not get the UART menu up even with your chip so can not change the TXF?

Regards, Ian.

[6666]

Good work Moodz

[moodz]

Great progress. Don't worry, I can assure you that despite much other posting real progress on detector technologies is being made.

Along with progress on RTOS code and hdphilip's experiments with it there are other 'R&D' activities underway.

For instance I just put your JPG through my 3D quantum resonance rotator so that I can read the part numbers. You should have painted them white or is that 'Whites' or the special shade of Minelab white that many (but not me) are familiar with?

Also, doesn't the pair of pliers you have balanced it on mask the target signal or is that part of the 'ground balance'?

In all seriousness: Well done. Great progress and thanks for reminding us what we are all really here for.

Chudster

Thats not a pair of pliers ... thats my precision surface mount placement tool
The FPGA runs a "soft core" 32 bit MIPs compatible processor though I may drop this in future code in favour of addon like the PIC32. There is a fully synchronous HDL implementation of a UNIPI controller in the FPGA with a 200 Mhz clock for fine timing resolution ... the core can do a bit north of 400 Mhz on a good day though.
moodz