Delta Pulse

[kt315]

that was discovered up millions years ago in Zakrzhevskij forum. nothing new for me. i did write you about the resistor - you began to dig
up all schematic. if every newbie will be give me 'new' lesson... i will blow up oneday AHAHA!!!

look... i am BRILLIANT MEMBER. i am here from 2002 year.

[Vadim18]

SNIFFER XR71 in brutal force style. okey. принимается. кто хочет - тот увидит. кто не хочет... значит не Судьба.
Q7, R36.

I may be wrong but...
Mistake №1 pnp transistor Q7 will be all time closed (untill button presed) and feed true tiny 100uA uMeter about 3000uA. Transistor Q7 must be NPN version.

Mistake №2 Any zener diode (and ZD2 too) need some minimal current bias to work properly that is usualy at least 0.5mA for 1W zener
Lets calculate current with 12k resistor U=12v-8.2V=3.8V 3.8V/12000 = 0.0003A 0.3 mA! to low!
Voltage on uMeter will be very temprature dependable.
Did Q7 PNP will go in open state if "Fast zero" presed?
Lets calculate voltage on R37 12K*0.3mA= 3.6 milivolts. 3.6mV will do nothing with Q7 even if "Fast zero" presed

"ZD2, R37, R36, Q7" dont make any change for main functionality, except they add battery udervoltage monitor, and do that with Q7 NPN version usualy.


Sorry for my leakage of knowledge if so i was wery bad student indead.
Did i passed your examination?

[kt315]

SNIFFER XR71 in brutal force style. okey. принимается. кто хочет - тот увидит. кто не хочет... значит не Судьба.
Q7, R36.

[Vadim18]

i meant R40 value.

R40 to 1K? That looks a little bit like modification in brutal force style)
I already checked shielding. I simply placed DP between PC PSU and CD-ROM and connect both to positive supply rail.
Yes shielding make 100% noticeable effect, one little step forward in stability.

[kt315]

i meant R40 value.

[Vadim18]

you can set 1k resistor 'like i see in shiff sniff sniff' and get low reset time.

https://www.geotech1.com/forums/album.php?albumid=56&attachmentid=40452

not so hard way to change resistor. but you will not hear a sound.
in my revision of board i added mod using 'free' cell of 4066 to reset SAT on Turn On. no more need to press reset knob.
i think you did not right shielding of the enclosure and meet a problem with ESFI.

Thanks for advice, Anatoliy.
Not sure how 1k (R39 or R36) resistor will affect here on reset time, as i see it used for uMeter biasing and undervoltage indication, i may be wrong.
I will try some shielding.

[liudengyuan]

I do n’t want to use a voltage as large as plus or minus five volts to power the op amp. I want to use plus or minus 2.5v, but since the gnd is 12v, how can I form a plus or minus 2.5v power supply, who can help me

[kt315]

you can set 1k resistor 'like i see in shiff sniff sniff' and get low reset time.

https://www.geotech1.com/forums/album.php?albumid=56&attachmentid=40452

not so hard way to change resistor. but you will not hear a sound.
in my revision of board i added mod using 'free' cell of 4066 to reset SAT on Turn On. no more need to press reset knob.
i think you did not right shielding of the enclosure and meet a problem with ESFI.

[Vadim18]

Seems like i late for this nice project for 10 years or so, but...
For how long Reset button should keept all unit in tuned, ie no sound, state?
I have around 30 seconds, than i need to pres one more time and so on, and so on. In my tests coil is fixed on table, interference is also not audible.
Can anyone of DeltaPulse owner's recall this?
Theory is less interested, at this moment.

Thanks.

[kt315]

DP circuit is working 'in circle', cyclically. that is mean in the start of the circle we must bring preamp
in a state of zeroing. ie TO RESET THE LF357 OUTPUT TO FULL ZERO VOLT because we have not 'classic' balance trimmer you see
around - in bara, in sirf, in hh (that is huge thermoinstability). yes, thats work of Sample and Hold Circuit, we call that SHC.
why this SHC here used? - because DP is fully STATIC/NON-MOTION very sensitivy aggregate.
ie this phase of the circle is going on BEFORE a phase of 'metal sniff-sniff-sniff'.

then it seems that controlling it does not make sense, can anyone explain
---
your fantazy.

[liudengyuan]

Can anyone explain the problem that tr2 controls the third pin of lf357, when tr2 is high, d9b is turned on, but at this time lf357 is not working, the output is zero, then it seems that controlling it does not make sense, can anyone explain

[kt315]

FIRST SAMPLE DELAY in every PI metal detector is working on CUTOFF. while certainly you LOSS THE DEPTH
if set the pot at right position. EVERY POT IS NEEDED BEING SET IN THE OPTIMAL POSITION. NO 'GOOD' OR 'BAD'
POSITION OF THE POTS. you do AIR TEST AND ASK ME HOW TO GET THE DEPTH IN AIR - THAT IS ABSOLUTELY NONSENCE.
pleasure

[walesto]

Thank you KT.
About DISC I was asking if I should increase it from min value to cut of some small items (nails, pieces of wire etc).
Best wishes and regards,
Tomek

[kt315]

[]Hi, yesterday I've made frame coil 90cm and today I had opportunity to test it on field.

According to my calculations it has inductance about 350-400uH and resistance with cable and additional resistor about 2,8 Ohm.

I increased Depth and T/Hold almost to maximum, but during the test it was able to catch iron plate of about 20x20cm from distance about 1m.

T/Hold does nothing. yes, that is deplorable fact for much people, but i'm not projectant of the DP circuit.
you must understand that. if i write 'set T/Hold in middle position and do not touch it never' thats sure mean you must set it in middle position
and do not touch. DISC pot in left position gives max depth in a test.

Geb and Sens were in the middle position.

GEB pot for test for max depth. set it in right position on max.
remember simplest rule - at left position you take more 'ground' part from 'delta pulse' signal, at right you take less part of 'ground'.
so in THE AIR no important there is the ground or not. you just seek a level of unstability on the ground and set the level slightly less.

SENS pot you set at max before the point of unstability. in 8-9-10 position if you CAN set the pot.

Shell I try other settings to catch such an iron a bit deeper? It would be great if it could be depth of about 1,5m.
I'm looking for iron meteorites containing about 7% of nickel.

i do not think 20x20cm plate is similar to real meteorite like as testing object. because meteorite is volumetric.

If I remember correctly the better for me could be lower frequency, about 100Hz.

we say about INTERFERENCE aspect with the electric nets around and
a try TO DECREASE the influence to minimum. thats why we choice aliquot value - those number 2 4 6 8 etc.
remember ariphmetics from school. so we choice 50 Herz x 2 thats sure 100 Hz, you can take 200 and 300
but your consumption current will be increasing on this number - in 2, in 3 times more.
simple rule then - if your batt hunting reserve was 3 hours with 100Hz then with 300Hz the time will be just 1 hour.
very simplest ariphmetics.

Is it possible to make settings to catch 20-30kg mass at depth of about 2m?

yes, this is really because big mass for a deeper is 'its original purpose'.


DISC then it is better to be in the middle or rather closer to max?

in air test - at min. on the ground that is 'CUT OFF' big objects from small ones. for simplification i call this pot DISC (i must transfer
all things on level of kitchen wify. main problem is that people do not wish learn main pulse induction principles waiting
ready-made pharmacy prescriptions for headaches from somebody).
in reality this is FIRST SAMPLE DELAY. min position 40us, max one is 160us. i do not think all rusty nails in field
is your matter of hunting. or.. i mistake?

take attention i did not recall the pots PULSE WIDTH, FIRST SAMPLE DELAY, SECOND SAMPLE DELAY, UNNECESSARY POT
that i has to do right... lol!

[walesto]

hi Tomek
....
for first test positions of the pots has to be -
- DEPTH - min, at left side, counter-clockwise
- DISC - min, at left, counter-clockwise
- GEB - middle
- SENS - middle
- T/HOLD - middle

Hi, yesterday I've made frame coil 90cm and today I had opportunity to test it on field.

According to my calculations it has inductance about 350-400uH and resistance with cable and additional resistor about 2,8 Ohm.

I increased Depth and T/Hold almost to maximum, but during the test it was able to catch iron plate of about 20x20cm from distance about 1m.

Geb and Sens were in the middle position.
Shell I try other settings to catch such an iron a bit deeper? It would be great if it could be depth of about 1,5m.
I'm looking for iron meteorites containing about 7% of nickel.

If I remember correctly the better for me could be lower frequency, about 100Hz.
Is it possible to make settings to catch 20-30kg mass at depth of about 2m?
DISC then it is better to be in the middle or rather closer to max?

Please forgive me if my questions are a bit silly.
At the moment I have no access to osciloscope.
I've read some teoretical answers, but I'm affraid thet I cannot catch it.
But anyway I would like to start from some point

Thank you in advance for any further suggestions.

Tomek.




My delta has freq about 200Hz - next week I think I will be able to measure it ...