RELIC HAWK

[Max]

Hi,
Ivconic told us it is no J-fet, just transistor.He knows what he says.

Max, what transistor did you use for audio output? BC517?

regards,
Fred.

Hi,
yes... about... it's a C517, Japan made.

Do you think at its higher gain as a problem ?

Kind regards,
Max

[ivconic]

No Tiktak, i am far away from any work in my workshop, for now. Resting and doing nothing.

Yes it is transistor for sure (is this deja vu or what??). It says "SR51" at both machines i had; RH and Colt. Later i found out it is BSR51 (guess they were lazy to print "B", or paint saving??) .
So if it is BSR51 than BC517 is proper replacement, although there are other transistors to do same job there...
But...than you still must use earphones. If speaker is nedeed than audio must be modded. Guess Bulgarians solution at Coinseeker could be a starting point...

[Max]

schematic update

Hi,
here's revision 1.9.

Corrected the "f" line according to the discovery made on Musketeer board.

Kind regards,
Max

[ivconic]

When tracing routes using posted photos, do not be confused with pin assignments....it is not usual!

[Fred]

O.T.

This is completely off topic but if anyone need a really tiny RS232 converter, here it is.
Just done this for GPS experiments but may be used for many applications, so i post it here
Regards,
Fred.

[KingJL]

I've made a simulation till comparators... and got about same phase I get from measures...

.... So, the PCB/circuit is like expected, no errors and timing is the same as from schematic we have.

This confirms problem is somewhere else... maybe at coil ?

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

[Max]

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,
my supply is at 12V +- 1%. Inside circuit I have 2.48V at TL431 regulator... and thus my GND level is at 4.96V.

So, considering GND as reference I have -4.96 for V- and +7.04 for V+.

The low battery thing I don't understand well still now... I tried to lower the voltage to see what happens but cannot hear anything... maybe there's another mistake in schematics in that part too.

In some military units the low battery gives a constant, steady tone... so prevent you using e.g. detector when in a minefield in such conditions.

I think ML used the same strategy used in that military units... but till now I didn't pay much attention to battery checker... must look at it better.

Kind regards,
Max

[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''.

[tiktak]

Hi

Hello Forum
Good news:19hours to release Minelab RH $200
http://cgi.ebay.com/MINELAB-Relic-HA...QQcmdZViewItem
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-...3286.m14.l1318

[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

[nakky]

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

[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

[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,
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

[nakky]

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