IDX-PRO+VDI

[gtdavid]

hello,
i have just noticed that the bc327 is running hot on my board is this normal?
i have checked the leg arrangements and they are correct.

[gtdavid]

ok it appears that running the tx circuit at 12v volts was the cause of the bc327 overheating..
i tried to upgrade the bc327 with a bd140-16 that worked but still overheated.
is there a one that you use when running tx at 12v ?
and also just to make shore the rx tank cap is one you place in parallel over the rx wires? or is it the 220n that i replace?

[golfnut]

I would leave making this mod for now mate until you can prove you need it.

I dont need to alter anything and nothing gets hot.


If your air tests are a bit short and your not happy try someone elses coil or a coinmaster or idx coil

should do 7" in ground with small coin fairly easy with disc rejecting iron.

S

[gtdavid]

I have noticed a difference since disconnecting the 12v from the tx .
Testing with a small ring.
With 12v tx - 23cm
With standard 8v tx - 17cm
Still not to shore about why the transistor was getting hot. How do you run your tx at 12v?
And also I made a 2 tone board on a prototype board and I got a high pitch hum from the bc327.
This may be my bad prototype board or could it be a problem on my pcb? ?
Thanks

[Koala]

I have noticed a difference since disconnecting the 12v from the tx .
Testing with a small ring.
With 12v tx - 23cm
With standard 8v tx - 17cm
Still not to shore about why the transistor was getting hot. How do you run your tx at 12v?
And also I made a 2 tone board on a prototype board and I got a high pitch hum from the bc327.
This may be my bad prototype board or could it be a problem on my pcb? ?
Thanks

Hi can you test with a coin and I will test with mine and a 8" coil and compare. Distance with rings can vary a lot. Type of gold, size, shape.

[gtdavid]

ok i have retested with a au $1 coin 24mm round.
26cm

[gtdavid]

can some one please tell me what is the best way to run tx from 12v
please

[Koala]

My nearest coin is 2p just under 26mm diameter just under 2mm thick and either copper or iron clad. Both iron and copper same distance 26.5cm same in disc and PP mode. Using 16 ohm headphones can get another cm in PP mode with 8 ohm speaker next to my ear. Disc mode nice clear tone is to 24 cm last 2.5cm broken dirty tone. That's with a standard whites 8" coil and no modificaions on a silverdog PCB. I take it is the 10.5" coil you have.

[gtdavid]

Yea mine is the 10.5 fisher cz
Yours makes mine look bad :-(

[Koala]

Somewhere on this thread silverdog was hooking up a CZ coil and questioned to caps quoted earlier in the thread as maybe wrong. They got it sorted but they have an oscilloscope and the cap values not posted. Post 766 asks but can't find repliy and post 407 requires an oscilloscope. . If you get not response to a PM to Ivconic silverdog or eduardo1979. Think using an oscilloscope might be your only option if you can beg or borrow one

[golfnut]

try a whites coil on it. i think the coinmaster or IDx are similar coils - can anyone confirm.


What are the resistance readings on your CZ coil.
Are you certain you have the Tx coil wired to your Tx

When you did a12v mod, did you cut the 8v feed on the pcb the the Tx transistor and add a local decoupler of about 0.1uF

If this mod isnt really working with your coil revert back to original design and splash out on a whites coil for it. Same as Koala





Or make a coil up - bit of a faff though

S

[adventureswithjim]

As for coils in real life use with a stock White's build (I used this machine for years as a treasure hunter...it's a beast!)...any white's 6.59khz machine. I could swap with coin master, 5900 and 6900 series, any classic and SOME XLT coils. The XLT coils that did work showed a lower performance. Beware I BELIEVE there are 2 different Blue Max 950 coils...one for classic series and one for XLT/DFX. The absolute best performance was the BLACK Max 950...it's thiner and runs hotter than the Blue Max. You can also use Blue Max 400, 800, 950 and 1500. (4", 8" 9.5" and 15") Bounty Hunter coils do not work, though still a 6.59khz, they are missing a cap in the coil housing that IDX expects to be there...but IDX could be modified to match I bet. The 4" gold coil by bounty hunter is a very effective design for precision work in tough places. I have not tested swapping Prizim coils, though friends who have report problems with it, it's hit or miss. Most of the the Blue Max coils are still readily available through kellyco and they have some nice charts on coil compatibility. The Black Max 950 is out production and virtually impossible to find sadly.

One other note...I've read through 37 pages of this...so far...I see many, many people having inconsistant results, highly variable performance...White's itself had consistancy issues! My machine was very, very senistive and very stable, I could easily locate targets of small coins over 10" deep and with the Blue Max 1500...small coins to 15", larger coins to 20". Yet other people I know who purchased the machine had very DIFFERENT results. Mine was stock, no Mr. Bill mods...and with that kind of performance, I simply wasn't going to screw around with it.

But over the decades of treasure hunting, there's one thing I've learned: depth is basically irrelevent. This is a gimmick the companies use to get people to buy the next model machine. Most VLF machines can hit 6" to 10" range, the real difference is in target seperation and working with iron. I think the IDX is an ideal platform for the VDI mods (which are awesome!) I have so many ideas to refine the IDX...getting ready to order parts, this thread is amazing for a true understanding of VDI and how IDX circuit actually works, thanks to everyone!

[golfnut]

Thx for that Jim

[gtdavid]

I did not add the decoupler cap. Where should I placw this ?
Silverdog helped me out with the rx cap I am now getting clear beep at 30 cm on the speaker (16 ohm).
I will keep trying different caps to see if I can improve on this result.

[gtdavid]

Has any one tried some ic swapping.
Example..
Lm358 to opa2277
Lm393 to max90
Thorghts?