RELIC HAWK

[Max]

Hi Max,
Thanks for new version
4024 supply change is very important , i may afect other stuff too.Did you try it after that?
For voltage detection i would intead try to play wut the 91K resistor value.

I dont think those errors where intentional.the all looks "logical" .
Hope someone here will buy the RH from UK and show some pictures.
That would be a job for mister Q, then he can sell it again...
Regards,
Fred.

Hi Fred,
well yes... it's really a stupid mistake there... but not so dramatic as effects if supply voltage is high enough... device will works too cause reset will get a logical zero.

Where it's really problematic ?

If you don't change that... the 4024 will simply stop working at 10.75V along with the rest of circuit ...gates...etc and you'll never be alerted of e.g. battery drop or why it suddenly die that way!

I think some bulgarian folk runs here and there with 3 or 4 batteries always fully charged! Cause still ask himself why that dang thing die at 10.75V!

PS: if not intentionally faked... how explain the schematic on page 1 ? I mean also there the reset connection is wrong (floating... so can get noise...) instead that at -Vee as required.

Kind regards,
Max

[Max]

Yes, very strange that they use such a big audio coil (15mH)just for earphones...they probably kept from other design.
regards,
Fred.

I think the 15mH is just a standard component they used in many different things... headphones or speaker... depensd on transistor stages.

You can run it happy with smaller 15mH coil... like neosid inductors... I have one in my PCB.

Sure... if I change 16ohm speaker for 4ohm or mount an hi current draining buzzer I MUST change it too... to meet new current requirements, or wire will "melt" at varnish due to heat.

Not a problem for now...

Kind regards,
Max

[Max]

I will return to audio again. Interesting thing is that RH uses only earphones, but Musketeer is using speaker (and eraphones if nedeed). So...skim look on both pcb's will lead to conclusion that both audio stages are same. Are they?
Now i am regreting even more cose didnt checked this before selling! Damn!
Imagine to connect speaker instead earphones on RH...what will happen?
I guess pretty weak,mum tone, not sharp an loud as with earphones. But on Musketeer tone is loud and sharp.
So...same schematic but speaker wirements must be different. Any ideas?
Just my 5 cents!

Hi,
they are different at audio stage: there are 2 SMD transistors in Musketeer that there aren't in RH. The 2 transistors are probably some push-pull stage but I'm not sure about...

You can see them here... difficault to follow cause tracks are partially covered by components.

I'm testing RH clone with 16ohm speaker and sound isn't loud... but you can hear, I think a simple 12V, self-oscillating buzzer will solve that problem without more pain but I've not tested that till now.

What I mean are some Murata kind... large buzzers with internal oscillator running on 2.8Khz.

Kind regards,
Max

[Fred]

I will return to audio again. Interesting thing is that RH uses only earphones, but Musketeer is using speaker (and eraphones if nedeed). So...skim look on both pcb's will lead to conclusion that both audio stages are same. Are they?
Now i am regreting even more cose didnt checked this before selling! Damn!
Imagine to connect speaker instead earphones on RH...what will happen?
I guess pretty weak,mum tone, not sharp an loud as with earphones. But on Musketeer tone is loud and sharp.
So...same schematic but speaker wirements must be different. Any ideas?
Just my 5 cents!

Yes, very strange that they use such a big audio coil (15mH)just for earphones...they probably kept from other design.
regards,
Fred.

[Fred]

Hi Max,
Thanks for new version
4024 supply change is very important , i may afect other stuff too.Did you try it after that?
For voltage detection i would intead try to play wut the 91K resistor value.

I dont think those errors where intentional.the all looks "logical" .
Hope someone here will buy the RH from UK and show some pictures.
That would be a job for mister Q, then he can sell it again...
Regards,
Fred.

[ivconic]

I will return to audio again. Interesting thing is that RH uses only earphones, but Musketeer is using speaker (and eraphones if nedeed). So...skim look on both pcb's will lead to conclusion that both audio stages are same. Are they?
Now i am regreting even more cose didnt checked this before selling! Damn!
Imagine to connect speaker instead earphones on RH...what will happen?
I guess pretty weak,mum tone, not sharp an loud as with earphones. But on Musketeer tone is loud and sharp.
So...same schematic but speaker wirements must be different. Any ideas?
Just my 5 cents!

[Max]

battery checker and other odd things...

Hi,
I've solved battery checker issue.

The first you need to look at 4024, look at pin2, reset. It must be connected at -Vee not at GND... this is a very stupid mistake or intentionally faked connection.

Then you can leave circuit as in schematic (if you still trust original one... ) and you'll get, about 1Hz pulsating tone when battery will drop under 7V.

Now the problem is... 7V for a 12V gel type means the battery is faked too... or damaged I mean... cause it's too low for normal, good operations. So you'll run device, this way, knowing zero about potential voltage imbalance due to battery till it will , in practice, die.

Smart solution:
put a 27K on pin14 of U11, then you'll get right pull-up action you need.

Behaviour is different this way: when battery goes down 9.45V you'll get a steady unbreaked tone... so you MUST know your battery is discharged.

Consider also that for gel cell this mean about 1.575V per cell, so a good value of discharge... rational and as expected for the unit and batteries of this kind.

The "smart" behaviour is like in AN/PSS-11 old mine detector... that I think inspired ML about this piece of circuit.... it's a steady tone for low battery, you wouldn't ignore it when on a minefield!

Here revision 2.0.

Kind regards,
Max

[nakky]

Max thanks for explanation,yes Iam still doing and waiting for news until there are no more mistakes in schematic.Grt Nakky.

[Max]

Hi,
I've simulated battery checker and seems with the simple 1n4148 it works, but need the famous pull-up on pin14.

The battery checker trigger alarm when voltage drops under 9.25v in this case... so about at 1.56v per cell, that's even more reasonable value.

So, I'll try to add the pull-up only and see if it works.

Then, if all OK I will made another revision of schematic.

Kind regards,
Max

[Max]

Hi Max ,Iam not a technician but make it difference if you swiths point 8 and 9 from U3.Grt Nakky.

Ops I was thinking at U11...

if you switch 8-9 at U3 change about nothing... cause it's bidirectional switch/gate so doesn't matter much which direction you choose.

Are you doing your PCB ?

Kind regards,
Max

[Max]

Hi Max ,Iam not a technician but make it difference if you swiths point 8 and 9 from U3.Grt Nakky.

Hi,
the real problem is the diode ... if you leave it there it will not work, need a zener there.

If leave a common diode there you'll need fairly large drop of battery to get it commutate.

I think there was a zener not a normal diode... but I'm not 100% sure of this.

Kind regards,
Max

[nakky]

Hi Max ,Iam not a technician but make it difference if you swiths point 8 and 9 from U3.Grt Nakky.

[Max]

mistakes... and more mistakes...

Max,
What are/is your battery(s)/supply level? I have found that some of the circuits REALLY do not like marginal voltage (especially the oscillator).

In that same area, I am still trying to find out what their "low battery warning" sounds like (the manual fails to tell you this).

Regards,
J. L. King

Hi,
I think there are other mistakes...

Looking at battery checker I found strange the absence of a pull-up resistor at pin14... so I think it's just another mistake there.

Also, I think the diode at comparator is actually some zener , 3v3 or something like this, another mistake there!

Now... with changes like in the picture... I think it will detect a 4.2-4.25V drop at battery... giving a steady tone to the speaker.

If battery is charged , each cell has voltage of about 2V... but to have 4.25v drop each cell must have (12-4.25)/6= 1.29V, that's reasonable for lead acid cells in heavy discharge.

Actually many manifacturers consider lead acid cells discharged already at 1.6V... but in RH probably the breakdown voltage is around 8V for the battery... when under 8V, say 7.75-7.8V, so about 35% voltage drop, the battery checker stops normal operations and start infinite singing.

Do you think I'm wrong on this ?

People that have used it for long time must know about this. Please confirm.

Kind regards,
Max

[tiktak]

Hi

Hello Forum
Good news:19hours to release Minelab RH $200

http://cgi.ebay.com/MINELAB-Relic-HAwk_W0QQitemZ280241608644QQihZ018QQcategoryZ14955QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

We can have it to see real circuit schematic!!!if somebody of the forum live in USA and can buy it for me (carl?)and for us(the Forum) , i will send money via western Union.
Alexis

Hi,
This is UK.Where are you located?Because I see that you have troubles with US.

http://cgi.ebay.co.uk/MINELAB-Relic-Hawk-Metal-detector-Excellent-condition_W0QQitemZ200237620107QQcmdZViewItem?hash=item200237620107&_trksid=p3286.m14.l1318

[tiktak]

Hi,

Hi,
Max.
I think its quiet just bip-bip-bip.
Like telephone with low batt.
But not shore.
The military trick is at getting targets so deep.
And once again there is some amlifer in the coil!You cant reach same thing without it!For this part we dont have any info.Maybe this gives so meny different measurments when trying to copy this DD15''.