Liberty II circuit

[WM6]

Found that this interesting vintage is "for coinshooting or dry land beach hunting".

Read this on Whites Liberty II from "cuda" on Findmall:

"I was at a yard sale a couple of weeks ago and purchased a Whites Liberty II that I bought for $5.00 because they thought it was a kids model since the shaft setting was all the way up. The only reason I bought it was to turn a profit but I used for fun and this detector blew my mind away with the depth and accuracy of the tone. I'm keeping this detector and ebaying the other two until I can afford a better model."

[silverdog]

Liberty II Coil

manual for Liberty II implies a 6B coil is required

some info I found:


White's

Name TX-L TX-R (ohms) TX-fo TX wire RX-L RX-R (ohms) RX-fo RX wire
________________________________________
6B 4" 1.74mH 7.71 --- --- 19.7mH 35.1 --- ---
6B 8" 1.72mH 6.47 --- --- 12.92mH 32.2 --- ---
6B 10" 1.69mH 6.68 --- --- 16.2mH 39.1 --- ---
6B 15" 1.59mH 6.36 --- --- 21.0mH 51.5 --- ---
Spectrum 9.5" 540uH 1.40 --- --- 36mH 122.8 --- ---
DFX 9.5" 540uH 2.67 --- --- 13.79mH 35.8 --- ---
Eclipse 5.3" 554uH 2.76 --- --- 14.01mH 31.1 --- ---
Eclipse 6x10 678uH 3.51 --- --- 14.19mH 54.6 --- ---
Bigfoot (XLT) 554uH 1.81 --- --- 43.0mH 146.7 --- ---

[ivconic]

manual for Liberty II implies a 6B coil is required

some info I found:


White's

Name TX-L TX-R (ohms) TX-fo TX wire RX-L RX-R (ohms) RX-fo RX wire
________________________________________
6B 4" 1.74mH 7.71 --- --- 19.7mH 35.1 --- ---
6B 8" 1.72mH 6.47 --- --- 12.92mH 32.2 --- ---
6B 10" 1.69mH 6.68 --- --- 16.2mH 39.1 --- ---
6B 15" 1.59mH 6.36 --- --- 21.0mH 51.5 --- ---
Spectrum 9.5" 540uH 1.40 --- --- 36mH 122.8 --- ---
DFX 9.5" 540uH 2.67 --- --- 13.79mH 35.8 --- ---
Eclipse 5.3" 554uH 2.76 --- --- 14.01mH 31.1 --- ---
Eclipse 6x10 678uH 3.51 --- --- 14.19mH 54.6 --- ---
Bigfoot (XLT) 554uH 1.81 --- --- 43.0mH 146.7 --- ---

Hmmm..i see. Than TX is not far bellow 1mH - but way over!
Maybe i will be pushed to make one..
Anyway; Silverdog thank You very much for effort! Helped me much!

[ivconic]

Found that this interesting vintage is "for coinshooting or dry land beach hunting".

Read this on Whites Liberty II from "cuda" on Findmall:

"I was at a yard sale a couple of weeks ago and purchased a Whites Liberty II that I bought for $5.00 because they thought it was a kids model since the shaft setting was all the way up. The only reason I bought it was to turn a profit but I used for fun and this detector blew my mind away with the depth and accuracy of the tone. I'm keeping this detector and ebaying the other two until I can afford a better model."

I have nose for such things - that's why Lahr's sketch attracted my attention so much!

[WM6]

Hmmm..i see. Than TX is not far bellow 1mH - but way over!
Maybe i will be pushed to make one..
Anyway; Silverdog thank You very much for effort! Helped me much!

Seems this worth to try:

6B 10"

TX L=1.69mH R=6.68E

RX L= 16.2mH R=39.1E

What about Altra's C=1uF in paralel with TX coil now?

6B is CC coil?

[Altra]

Silverdog is right the coils are not exactly the same. But all the coils run at 6590Hz.
So if you wind a coil based on the XLT 540uH, you need around 1uf in parallel to resonate
at 6590Hz. If you use the older higher inductance, you will have to do the math for a different capacitor. Maybe around 330nF. I mention the XLT coil because they run at the same frequency and there are alot of them around. The xlt windings are compatable with the liberty circuits. In other words it will not start a fire. Any slight phase differences can be adjusted on the pcb - LM393 circuits or preamp.

Mark

[WM6]

Silverdog is right the coils are not exactly the same. But all the coils run at 6590Hz.
So if you wind a coil based on the XLT 540uH, you need around 1uf in parallel to resonate
at 6590Hz. If you use the older higher inductance, you will have to do the math for a different capacitor. Maybe around 330nF. I mention the XLT coil because they run at the same frequency and there are alot of them around. The xlt windings are compatable with the liberty circuits. In other words it will not start a fire. Any slight phase differences can be adjusted on the pcb - LM393 circuits or preamp.

Mark

Sounds logical, thanks Altra.

Then, for TX 1.69mH, C parallel at 6590Hz is 345nF.

[silverdog]

Liberty II

A couple of minor points;

LM324 has some pins duplicated - 12,13,14 are used twice

The disc pot outer pins on the PCB are not connected to anything

Watching this with interest , I have a blue Max 256 coil doing nothing

With this and 2 x IGSL, Mrs Silverdog will be having words with Ivconic !!

[WM6]

With this and 2 x IGSL, Mrs Silverdog will be having words with Ivconic !!

Assume that she is willing to check ivconic PCBs for further errors?

[silverdog]

[quote=With this and 2 x IGSL, Mrs Silverdog will be having words with Ivconic !![/quote]


English Humour !!
I mean she will want to know what all the pcb's are I keep trying to sneak into the house !

[ivconic]

A couple of minor points;

LM324 has some pins duplicated - 12,13,14 are used twice

The disc pot outer pins on the PCB are not connected to anything

Watching this with interest , I have a blue Max 256 coil doing nothing

With this and 2 x IGSL, Mrs Silverdog will be having words with Ivconic !!

Sheeeesh! That's right!
I completely forgot to correct&update schematic (do not be surprised, it is almost the rule at all of my works)!?
...
OK, i will explain why is this happening pretty often to me.
Here is how i usually do such things:
First i get idea and draw it in ExpressSch, (this time idea was from White's and i just input schematic)
than i print it on paper,
than i am watching at paper and manually draw pcb in SL5,
During pcb drawing, often turns to be more convenient to rotate some dual or quad op amp and orientate it in different position than i imagined from a start. That often can qualify use of another op amp segment - not the one which will accord to pin assignments as on schematic.
So, during process of drawing pcb, pretty often i am pushed to change pins and use different ones than those noted on schematic.
I do correct them on printed paper... but later forget (or am to lazy) to input those corrections in ExpressSCH file..
I am doing many things at the same time, always in a hurry and that's why those things are happening. Not bad intention - just my negligence.
It not suppose to present significant obstacle to those DIY-ers who are making similar things more often. It is logical and recognizable on the very first look.
Opamp is opamp.. not big deal if you gonna use any one of those 4 from quad, or anyone of those 2 from dual.
So, pcb is the one to respect. It is made, corrected and tested.
Disc outer pins are connected with wire jumpers, because i was not sure how i will place pcb in further enclosure: with components faced up... or faced down. So i wanted to void Disc command to be "reversed" on front panel, starting from maximum to minimum clockwise!
That's why i put holes for wire jumpers, so later will be easy to cross outer pins, if needed! (smart as a bee)

[WM6]

than i am watching at paper and manually draw pcb in SL5,

Maybe you urgently need a good autoruter (autoplacer inclusive).

[ivconic]

Maybe you urgently need a good autoruter (autoplacer inclusive).

I worked in the past in EDA Client. I simply don't like autorouter!
It is not smart enough, for my account!
Most enjoyable part of process, for me, is pcb routing. I just don't want to miss that.
It is sort of puzzle game for me. Even if i never make some design - i will enjoy drawing and routing it.. sort of a hobby!

[ivconic]

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[ivconic]

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