IDX-PRO+VDI

[Koala]

Yes.

The more stable the capacitors the more stable and less drifting your detector will be

I used polyester for mine except for the polarized ones around the PSU and is fine

Two of the caps on the original Whites board were 1% can't remember which two they were see if I can look it up for you.

Just checked an original board none of the capacitors are 1% it was two resistors that were 1% R47 and R48

[jlsilicon]

Why is the Gain Resistor 170K on the 5534 ?
- Why not use 1M resistor ?

How about replacing 5534 with Opa627 or Opa637 ?
Any improvement with this - do you think ?

[golfnut]

the 180k gives 45dB Av

Any more would saturate on big targets, have instability problems, have dc offset issues? boost mains pickup etc

[Koala]

Why is the Gain Resistor 170K on the 5534 ?
- Why not use 1M resistor ?

How about replacing 5534 with Opa627 or Opa637 ?
Any improvement with this - do you think ?

I used Ropcsika component list post 902
ic's: u1 5534
u2 cd4066
u3 lf347
u4 lm393
u5 lm358
u6 lm358
u7 lm393
u8 lm393

gives nearly 40cm with a 27DD coil on a old copper UK 2p in the air. and 100% stable. don't think you can squeeze any more out of this design and still be usable in the field.

[jlsilicon]

How about the opa354 ?

[jlsilicon]

According to my calculations, the 5534 opamp filter allows the pass through Band between of about 1KHz to 200KHz.
Does this calculate right ?

[ampirate]

Actually, I tried a 2n3819 across the coil with a few resistors - with the 5534 still attached.
The 3819 seemed to give a smoother and a lot more dramatic results
- according to my Datascope,
than the 5534 results.

[jlsilicon]

So how about the CTX3030 COIL with 1KHz to 100KHz capability ..
Does anybody know the specs for it - Inductance, Windings, Caps ?
How is this done ?

[Koala]

So how about the CTX3030 COIL with 1KHz to 100KHz capability ..
Does anybody know the specs for it - Inductance, Windings, Caps ?
How is this done ?

Sorry no idea. Quick Google search came back with nothing.

Do you have a CTX 3030 coil already as the cost on eBay would be about the same as a 950 BlueMax

[golfnut]

My new IDX pro board with pot in board.

[ATTACH]31299[/ATTACH]

Really neat,classy good engineering solution.

This would help get repeatable units between builders

[jlsilicon]

Just the regular POLY FILM Green Blob Caps will be good enough ?

Yes.
The more stable the capacitors the more stable and less drifting your detector will be
I used polyester for mine except for the polarized ones around the PSU and is fine
Two of the caps on the original Whites board were 1% can't remember which two they were see if I can look it up for you.

[Koala]

Just the regular POLY FILM Green Blob Caps will be good enough ?

Yes

Something like these are fine.

Used them on my Baracuda build works great.

[golfnut]

pps have some minor advantages at these frequencies. But the cost is a big factor.

I used them in sythesiser loop filter one time and they gave the best performance.

they have about the lowest loss, ( tan delta ) I think I saw them in an XP machine,, could be mistaken.


They can melt soldering them too if your not used to them especially the sm ones


general polycarbonate or polyester are fine as Koala says, the supplied ones in Silverdogs kit work fine too



Had a crack with the deus in sea yesterday got nowt, one coke can about 8" down.

Loads of 80s ring pulls in the dunes to 7 or 8" plus a couple of coins off the sandy bit where people lie on in front of the dunes

[Koala]

jlsilicon

I would advise you to buy your ICs from a reliable source. Farnell or RS and others post the specs on there chips. Go for the best ones they are only a few pence more. Ebay ect the supplier could be shipping good or B stock you have no way of telling. For most projects out of spec ICs make no difference so you can't go by feedback.

[dAYek]

Hello guys.
My name is Darek and I am writing from Poland.
Thanks to this topic we have finally built ourown IDX PROs - PCB kits from Andy the Silverdog, shaft from Armand detectors, DD coil built completely on ourown.
But we have a problem with volume control...
We have already changed the piezzo speakers to bigger speakers (one taken out of a telephone handspeaker and one taken out of the computer - typical 8 Ohm and 0.5W one) but still, the voice level is too low :-(. The speaker can be heard while working in the wood or in an abondonded field but not in the neighbourhood of the households or a road. On Sunday I was trying to use it next to a guy using two tone Technotics and I could not hear anything... So the question is - what can be done to make the detector louder? Cause as I have already mentioned - a bigger speaker is not a solution...
I am looking forward to hearing from you - more experienced guys.
Darek