RELIC HAWK

[erolunall]

Hello
I saw schematic on this link and post link here but
I dont know bulgarian language
I cant find it now.
maybe somebody load schematic on this link.
Sorry I dont know anything.
Best Wishes
Erol

[Unregistered]

Thanks anyway!
Unless I now this

[tiktak]

Hi,

Hi,
I just finish the PCB.But I still cant understand some conections.
I will be glad if someone help with this isue.Simple picture or something like this.
Thanks.
p.s.cant wait to see the results.
Also there is cap with no label left from U13?Is this 100n dec.cap?

[Max]

some caps around....

Hi,
here are some pics of my RH board... look downside... there's a network of decoupling caps there!

Maybe pics are a bit (!) out of focus but you can see the small black caps (100nf) there... connected by flying wire joints... (if not use imagination cause my camera refused to make better job! )

That's a simple workaround for missing decoupling caps on pcb... but sure you need the screws as spacers to avoid messing the caps and make a big shortcircuit down the pcb!

Kind regards,
Max

[Fred]

Hi Max,
One solution could be to solder SMD caps between pins and ground plane, on the components side.

[Max]

Hi Max,
One solution could be to solder SMD caps between pins and ground plane, on the components side.

Hi,
yes, right. That's good idea but require good eyesight too... for me is not big trouble but I made that way cause cannot find some bags of SMD stuff...

I had a huge collection of smd caps but put in bags a couple of years ago... then the bags disappeared!

Mean me or someone else put that stuff in a trash can or something... or in garage with other garbage...

Big troubles when you need smd ... the dang shops don't sell anymore (if not in BIG quantity) and you're in a hurry to finish RH !

So I found some garbage poly caps and soldered back.

The method is effective also for people who cannot find SMD parts easy.

But, sure, RH require in any case good shielding too during tests like e.g. metallic box you put inside everything... mount e.g. pots on metal panel etc otherwise it gets lot of noise from stuff around and become easy erratic.

Anyway, that board worked about 95% perfect when mods done... and things shielded so... COIL is real trouble I think.

Kind regards,
Max

[Fred]

Ok Max,
I have bought a box of SMD caps and resitors on ebay (from china), they are really cheap ,you have all values and plenty of them...
On good thing would be to make a RH PCB with SMd´s .
I´m afraid through hole components are going to disapear, but you can easily get used to SMD, there are not so bad ...

[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

[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.

[N@SKO]

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

[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

[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.

[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.

[Ultimate_Haze]

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

[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