field test unit no 001 "model T"

[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.

[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

[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]

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

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]

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]

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

[Davor]

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

[moodz]

avalanche is only dangerous for skiers LOL ....

[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

[chudster]

hdphilip,

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

Chudster

[hdphilip]

it's the green trace that's most important

[chudster]

Is that green with envy?

[Aziz]

Hi all,

when looking at the white trace (flyback voltage), I hope, the avalanche state behaves always the same (not varying). Otherwise, you will get more noise.

But I generally don't like avalanching the mosfet. Avoid it at all cost.
Aziz

[hdphilip]

Irf740 Vs, Cree Sic.....


Here's some pictures of my comparison between the Irf 740 (right) and the Cree silicon carbide MOSFET's(left). keep in mind the coil isn't the greatest(made from cat 5), neither is the coax between the coil and the front end board (4 ft RG174). the front end is simililar to carl's hammerhead, with a cree Sic diode between the coil and the mosfet.

Is it worth the extra cost? and also being twice as big.... you be the judge......

Philip