Delta Pulse

[Great_Alex]

auto tracking is very good facilities , with auto track you search in mineral soil and diffrent type of soil very silent and better depth.
but very fast auto track , reduce the detector response on deep target


deep targets have long signal length and increase signal more slowly than shallow targets
and fast auto track mask the target.

another important fact for delta pulse is :
the delta pulse has many setting and in field work the detector should be have the least adjusting setting cause it make the operator confused

i want to reduce the number of parameters and change them for my reasion - Finding big and deep metal with 1m*1m coil- not coins with 30cm coil

did anyone has idea about changing the Power - Disc - Range - Sens ... with constant resistor for this situation

i think we can do this for all knobs but sens need to be variable

[Jose]

Hello Great_Alex
I agree with the slow response to deep targets, in automatic mode.
The controls can be set in my humble opinion are:
RANGE: Replace R 250K P2 fixed. 1.5 nF C6 substituted by 1 nf, tended a sample of 250 usec or so, I think is enough.
TX POWER: internal preset adjusted from 125 to 150 usec. (I got the best results)
DELAY: I think it can not be replaced, you can expand the range to use coils C4 changing fast response of 1.5 nf nf 1, R7 changed to 10k 15k
SENS and THRESOLD: I should keep them as they are.
You may experience disabling the automatic control of "Delay" (T2, T3) and increase the value of R6, 1K (1.5 to 2.2K) for more stability in some cases, lower turns coils.
These experiments can improve or worsen the performance of the MD, according to the particular circumstances of each case, the risk borne by the operator.
Best Regards
Jose

[Great_Alex]

Hi jose

Are T2 & T3 for automatic delay control of ? I already think they are for high voltage shock and absorb extra amount of fly back voltage

about the Delay : i found it's not so useful for ignore hotrocks and viscose magnetized objects like ancient bricks ! i prefer to use a fast response i use 2k resistor as p1

I want to have reverse signal on vco it means when a metal approach to coil the sound decrease ! and when take it away the sound increase ?

best regards
Alex

[Jose]

Hello Grat_Alex
Do not really know what it's called this circuit but this is what he does.
Suppose you adjust the delay of 20 usec, then approached a metal coil, the delay runs automatically to 25 usec. This is by action of T3 and T2 on the DELAY circuit (pin 2, 453. It can be observed with the oscilloscope.
If we use small coils of fast driving, this circuit can be disabled by opening the collector (C) T2 or T3 for a smoother adjustment of time delay and in some cases stability, also helps increase the value of R6.
Again, this is valid to use small coils (20 to 28 cm) of rapid delayed, home of small objects.
If you use large coils and will not detect the ceramics, I should not make these changes.
I particularly prefer to use a potentiometer in the delay that use coils of different sizes.
Concerning this last paragraph, I think that you mentioned is what the original circuit, I'm sorry I can not add anything else.
regards

[kt315]

Do not really know what it's called this circuit but this is what he does.

i call this circuit first protect stage against an overloading. IMO this is too closer to stage function.

Are T2 & T3 for automatic delay control of ?

not. they begin to work (to turn on) ONLY on pretty big target you move a coil on.

yours

[Jose]

Thank you for clarifying the concepts kt315.
Jose

[raff33]

Hi,
please can anyone gide me how to get my delta pulse frequencey with my digital multimeter ?
- where connect black and red leads ?
- should i mesure frequency without connecting coil ?
Regards

[Jose]

Hello Raff33
Set the multimeter in frequency counter function
Punta black on - E, red lead on pin 9 of IC 556.
It can perform with the coil disconnected.
Regards
Jose

[raff33]

Hello Raff33
Set the multimeter in frequency counter function
Punta black on - E, red lead on pin 9 of IC 556.
It can perform with the coil disconnected.
Regards
Jose

Hi jose,
now i inderstand ......
- black lead on -E(pin7 of LM556).
- red lead on (pin 9 of LM556).
many thanks
REGARDS

[boeNorway]

hmm

whats the price for all the components for the Delta Pulse
and was there someone here that sold the 2 side pcb if i asked nice


ore is there some one here ho is ready to bild another metall detector and dont nead
the Delta Pulse pcb and components


Sorry for being bad at spelling but im made this way .


Best Regards to all of you .
this Thread was werry intresting .

[fidamohd82]

hi to all
i made the delta pulse it is working but with no depth just 3 or 4 cm
what will i do

[homefire]

hi to all
i made the delta pulse it is working but with no depth just 3 or 4 cm
what will i do

If you in fact built by the schematic and used the correct parts, how did you build the coil?

[fidamohd82]

hi
and what do you advise about the coil

regard

[DOOLEY]

hello all ,
been looking at the delta pulse and xr71 schematic , and i'm a little puzzled , hope somone can explain.

below is two extracted pics from dp / xr71 ,

firstly , the two op-amp's u4 and u6b , look to be feeding back / in a feed back loop , why is this , what is the purpose , checked on the net and can't find any examples that have this configuration to get an explination of what's going on.

my first thought was a type of automatic gain adjustment or automatic leveling of signal , the nearest thing i found that looked close was a high pass filter.

next question , i notice that the first op-amp , u4 has the same feed as the search coil , 12V , how can this work , as far as i was aware , the first op-amp requires a hight supply than the singnal which its dealing with , in this case it's 12.7V ish down to 12V , yet u4 appears to only have a 12V supply , ( +E) same as the search coil.

and lastly in the power supply pic , u6a , looks to delivering a regulated , but low current 5.3V supply to a reil noted with the ground symbol , been trying to work out a voltage scale for this detector , (-12V) = 0v
(-E)=1.4v
earth=5.3v
(+E)=12v
can't see anything higher than 12v so still puzzled as to how u4 can work.

i could be blind , and haven't seen it yet , but this is doing my head in , please help.

pics on next post , forgot to add.

[DOOLEY]

hello , pics below.