Delta Pulse

[kt315]

what type of coil you want? demountable or undemountable?

[mushaba]

what type of coil you want? demountable or undemountable?

Probaply demountable because i will have to dismantle it so it can travel...I made as the photo below 4 pieces that a square wood is glued to one wooden broom stick.Then it can be assembled and locked with pastic pins.I think it would be ridgid..

My question is what kind of wire (single core or multistrand) 1mm?1,5mm? And how many turns.

[mushaba]

Tried a 1 x 1 with 1.0mm multistrand wire PVC insulated,10 turns gave 370uH and 1.1 Ohm resistance,should the resistance be that low?

[Jose]

The resistance of the coil is correct.
I built a similar coil and the resistance and inductance values are similar too.
Experiment, with the damping resistance to get the correct value, and it should work fine.
Adjust frecuncia for better stability.
If it is necessary to improve the stability, try a series resistance of 1 ohms 5 watts with the coil.
When it achieves optimal performance,try eliminate the series resistance.

[mushaba]

The resistance of the coil is correct.
I built a similar coil and the resistance and inductance values are similar too.
Experiment, with the damping resistance to get the correct value, and it should work fine.
Adjust frecuncia for better stability.
If it is necessary to improve the stability, try a series resistance of 1 ohms 5 watts with the coil.
When it achieves optimal performance,try eliminate the series resistance.

Hello Jose!
Just tested indoors the square coil,i have it supported on a wooden pallete because my other coil carriage isnt glued completely.
It damps near 128 Ohms,strange thing my other monocoil for delta i built (50cm OD 0,55mm double enameled coil wire 375uH 2 Ohms) damped with same resistor value,is that normal??
The damping precedure i make with 3 different pot-resistor sets..

It seems to work great but it "hits" many ferrous targets as my workshop is mainly constructed with steel.

[Jose]

The damping resistance of 128 ohms is low.
For medium or small bobbins from 30 to 50 cm. I use CAT5 cable. The resistance is around 2; 3 ohms and the damping resistance of 400 ohm, more or less.
You can use common cable with PVC insulation, 0.5 mm in diameter, or larger.
The enameled wire greatly increases the capacity of the coil. This may be the reason why it requires low damping resistance.
The coils of 1X1 mtrs, requires less resistance of damping, because it has greater capacity between turns. A normal value would be between 200 and 400 ohms, I do not remember the exact value of my coil.
What I do in my DP, to use coils of different sizes, is to install in the DP box a dampening resistance of higher value than normal, for example 560 ohms.
Then I installed resistors in each coil that determined its value experimentally.

[mushaba]

Ok,understood.

I believe that high capacitance to my 50cm coil is due to long leads (1m) to connect directly to detector..

Today I will cut the leads near coil,solder RG58,re-damp it to see the value of resistor and then I will attach it to the crossbow to see differences (almost same current resistor in series with coil from schematic,same irf and diode)..

[Jose]

Hello Jose!
Just tested indoors the square coil,i have it supported on a wooden pallete because my other coil carriage isnt glued completely.
It damps near 128 Ohms,strange thing my other monocoil for delta i built (50cm OD 0,55mm double enameled coil wire 375uH 2 Ohms) damped with same resistor value,is that normal??
The damping precedure i make with 3 different pot-resistor sets..

It seems to work great but it "hits" many ferrous targets as my workshop is mainly constructed with steel.

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If I understood correctly, the 50 cm coil is made of enameled wire.
If so, the coil would be the cause of the high capacity.

[mushaba]

If I understood correctly, the 50 cm coil is made of enameled wire.
If so, the coil would be the cause of the high capacity.

Yes Jose you understand correctly,please excuse my bad enlish..I meant that porsion of this capacity is also from coil leads i left long to connect them directly to detector...Took it for a field test with the 50cm coil,it has great depth on large targets..Think i noticed is that GEB doesn seem to affect anything,when i lowered the coil near to earth i got continuous sound,lift it 10cm and the sound stopped.Tried to calibrate via pot the GEB but i did not notice the difference,i did a mistake not to shield the coil before i potted into mdf

[kt315]

if you want buy not chinese LF356
https://www.ebay.com/itm/TDB0156DP-L...gAAOSwcLxYKeFw

[mushaba]

Have Thompson made lf's but not like the one in your photo Have it also on Felezjoo and it works great.I think my problem is more likely to coil not being shielded,aside that the do works extremely well..

[kt315]

1 x 1m coil and more size one are not shielded and working good. i think your problem you still do not understand a value of needed shielding of housing/box.

[mushaba]

1 x 1m coil and more size one are not shielded and working good. i think your problem you still do not understand a value of needed shielding of housing/box.

Did you see attachments on post #3553 ? What more?

[kt315]

i meant 'Felezjoo' in your post above. you write Have it also on Felezjoo and it works great.I think my problem is more likely to coil not being shielded

[mushaba]

Ok!I followed your instructions on plastic case shielding,used coper lines and graphite spray on both DP and Felezjoo builds,I did not shield my 50cm OD coil housing...Also I though that 1x1 needed shield...Are there any DP boards left?