RELIC HAWK

[gurdal]

A very good speech detector. groundwater depth is distance?

[Max]

Our good friend Nakky found 3 errors so far, on this pcb. I corrected those and here it is latest file.
Many thanks to Nakky!
Best regards!

Hi,
seems nice, no matter it's 16x10 ...who care about ?

It's ok having a large board on RH clones... cause spacing is also a key to get less noise from crosstalks there. In board I've made, by Fred, then modified a bit to overcome little mistakes I found high crosstalks effects cause of "small" wiring and upper tracks. I ended up finding also a ground loop I had to remove before get it to work right way.

The larger board could suffer much less of all that situations and having decoupling caps through hole it's not bad idea... the opposite!

In my prototype I had to fly-mount downside all that caps... resulting in a big mess to look at when downside! But it works, anyway.

Now...you made excelent new single side board and so your next challenge is mounting it and testing with coils... but I'm sure you'll do soon !

Keep waiting for the good news!

Kind regards,
Max

[ivconic]

Our good friend Nakky found 3 errors so far, on this pcb. I corrected those and here it is latest file.
Many thanks to Nakky!
Best regards!

[ivconic]

This is "mo' better blues" file. Not optimized 100% yet, but good staring point to check and correct more. For those interested...
Still checking for eventuall mistakes. When i will be 100% sure that it is absolute correct , i will let you know. This thing is going to slowly at me, cose i have much other things to do, these days.
Regards!

[nakky]

Hi Ivconic,this is Great,you doing a lot of work.I start with it but long not finish.You are still better with Sprint layout.Thank you very much.Grt Nakky.

[Ultimate_Haze]

Greate.
I have spend also wast days trying to draw PCB with no luck!Real puzel.
Excelent work!
It can be optimized later but hard work is done now.
I like it very much.Look real cute.

[ivconic]

Yes...looks ok. I just finished pcb. It is HUGE!
I dont mind at all. It is through hole, single sided and all the gnd coupling caps are on their places. Good thing is that top layer also can be ground plane. Come to think..; it is not so huge, not bigger than original RH or Musketeer...
I "crossed" many gnd vias, especially across critical paths. Payed a lot of attention on S/N ratio and hopefully this will "choke" any eventual internal hum. Of course there are many gnd traces that can be carnified, exalted and make a small zones of those. When rechecking i wil also correct those to cover more area on empty pcb space. Pcb is approx 16x10cm... Detailed draw will post after checking.
Just finished and very tired. Next days i wil recheck from errors.

[Max]

I was thinking to make a fresh start again, with this project. Few things i remembered from the time when worked with Relic Hawk and Colt; first, those machines looks really identical in many things, second, i used Relic Hawk mostly in S mode. It was very deep for coins, very, very deep. So.. to reduce schematic, therefore to reduce pcb and also to improve S/N ratio on future pcb, i decided to omit parts for mode switching. Dont need M and L modes at all. Also i dont like original RH audio. Earphones! Damn earphones, i am never using those anyway. Audio was adopted from Sasho's 2 tone project, which i recently made and tested and it turned to be extremly good and loud. So, major changes here are; new, but proven audio output and no M and L modes, parts and switches. All the rest remained the same as on last schematic from this thread. Before start drawing new pcb i would like all of you intereseted to take a good look on this schematic and check if there is any mistake, or... if you have some remarks or hints, please do not hesitate to say here.
Best regards!

P.S.
Oh yes! Almost forgot! There are some opamps changed; quadro splitted to 2 dual's or dual splitted to single opamp etc...etc.. I did that keeping in mind further placement on new pcb and trying to void some very complex and long traces. Only reason. Somehow to void complicated and crossed traces and vias...therefore this to optimize better and improve S/N ratio... Do not be confused about this.

Hi,
seems ok, but not checked 100% so something maybe I didn't spot.

I'm doing a lot of things (not electronics hobby) at now... but sure I'm still interested in RH progress too.

Hope you'll realize one.

Kind regards,
Max

[Ultimate_Haze]

Greate!
I have a hunch that this will be good!

[ivconic]

I was thinking to make a fresh start again, with this project. Few things i remembered from the time when worked with Relic Hawk and Colt; first, those machines looks really identical in many things, second, i used Relic Hawk mostly in S mode. It was very deep for coins, very, very deep. So.. to reduce schematic, therefore to reduce pcb and also to improve S/N ratio on future pcb, i decided to omit parts for mode switching. Dont need M and L modes at all. Also i dont like original RH audio. Earphones! Damn earphones, i am never using those anyway. Audio was adopted from Sasho's 2 tone project, which i recently made and tested and it turned to be extremly good and loud. So, major changes here are; new, but proven audio output and no M and L modes, parts and switches. All the rest remained the same as on last schematic from this thread. Before start drawing new pcb i would like all of you intereseted to take a good look on this schematic and check if there is any mistake, or... if you have some remarks or hints, please do not hesitate to say here.
Best regards!

P.S.
Oh yes! Almost forgot! There are some opamps changed; quadro splitted to 2 dual's or dual splitted to single opamp etc...etc.. I did that keeping in mind further placement on new pcb and trying to void some very complex and long traces. Only reason. Somehow to void complicated and crossed traces and vias...therefore this to optimize better and improve S/N ratio... Do not be confused about this.

[porkluvr]

The oscilator work with coil 3 oms or more!Only must change the place of R5 and R8 (10k;27K)

I tried suggestion but it did not work. Oscillation died faster than before. Transistor selection may make a difference so this deserves more attention. And of course my virtual circuit is not real, so if it works for you, then I can't argue with results.

After swapping the resistors back I wanted to return circuit to functional condition but I made a mistake and made series resistance = 2m2, (.0022) instead of 2.2Ω.
Hmmm... when I said before that it looked excellent with zero coil resistance, I should have run simulation for about 30ms longer and I could have watched it malfunction. The amplitude feedback network runs out of headroom, then resets and causes extreme amplitude instability.

It looks like the circuit is even more touchy than I originally thought. If you have the coil resistance either too high, OR too low you could run into problems. But it's a thing of beauty when properly tuned. 10V in, 16V out and LOW distortion! (WOW.)

Hey, MAX, good to see you back.

[Max]

I simulated the TX oscillator section. Using coil resistance = 0 gave excellent results, but was a unrealistic test. Inserting 3Ω series resistance
caused the oscillator to fail. What went wrong, did I make any obvious mistakes... ?
Then I saw a note on Max's schematic, and changed coil series resistance to 2.2Ω. Now, TX oscillator outputs a very clean 5kHz signal at
about 17Vp-p. Amazing.

From this experiment I gather that RH coil resistance is critical. Anybody having poor results should keep this in mind. The top trace is with
a 3Ω coil, bottom trace 2.2Ω coil. Everything else is the same.

I know my spice transistors aren't the same as the original, but I've seen two schematics and each had different values. I don't have all the
models I need, or else I would plug in the "correct" parts (both versions). I believe the transistors are also fairly critical, but some BCxxx models are
missing from my collection.

Hi,
yes, you wrote all right: coil resistance is critical and transistor at osc stage also.
I had to make different tests there to get good sinus and stable oscillations , otherwise nothing to do. VERY CRITICAL part of circuit... maybe designed that way for fooling cloners!
Well... it's that way cause voltage at coil is fairly high at resonance, so very strong magnetic field also... though this can also be a problem (e.g. far iron detection and soil effects).

I remember I had to order also particular diameter wire (cause I run out of it before making test coils): I used copper wire, but original is aluminium as far I remember, and resistance depends also on these "details".

Kind regards,
Max

[N@SKO]

The oscilator work with coil 3 oms or more!Only must change the place
of R5 and R8 (10k;27K)

[porkluvr]

I simulated the TX oscillator section. Using coil resistance = 0 gave excellent results, but was a unrealistic test. Inserting 3Ω series resistance
caused the oscillator to fail. What went wrong, did I make any obvious mistakes... ?

Then I saw a note on Max's schematic, and changed coil series resistance to 2.2Ω. Now, TX oscillator outputs a very clean 5kHz signal at
about 17Vp-p. Amazing.

From this experiment I gather that RH coil resistance is critical. Anybody having poor results should keep this in mind. The top trace is with
a 3Ω coil, bottom trace 2.2Ω coil. Everything else is the same.

I know my spice transistors aren't the same as the original, but I've seen two schematics and each had different values. I don't have all the
models I need, or else I would plug in the "correct" parts (both versions). I believe the transistors are also fairly critical, but some BCxxx models are
missing from my collection.

[Max]

that's component side...

used lot of stuff there... included scrap caps!

Well... it's not too bad anyway... considering was soldered a million times... redrilled also in some places!

PS: the three caps .33 uF were selected to match exactly 5Khz with coil...

Kind regards,
Max