RELIC HAWK

[Max]

Hi,
Thanks for answers!
I am beginning the PCB.
Some observations:
-The capacitor in // with the TX coil is 1uF ??!!
-U13 has only one gate used , i suppose unused pins are left unconnected .
-I dont think i will be able to make it single side, but i will try to keep this as an option ,that can be compensated by wirings.
-I will assume that the inductor connected in serie with the RX coil is the size of a 0,5W resistor.

If you have any comment on this or other part please let me know.

Regards!,
Fred.

Hi,
U13 is 4024, so counter not gates there... but yes just 3 relevant pins used + supply.

All the rest seems OK to me. If you can, avoid upper traces and go for jumpers on the upper side: many people can make here very nice single sided PCB with lot of jumpers if needed but just a few can do good a complex double sided one.

This is not a problem for me... I have double sided quality presensitized boards... but could be real trouble for those who haven't and this will complicate and slow down the cooperative work on this thread.

Anyway... if you see too complex... do it double sided.

PS: don't forget decoupling caps... are important in RH.

Kind regards,
Max

[Geo]

Hi,
Thanks for answers!
I am beginning the PCB.
Some observations:
-The capacitor in // with the TX coil is 1uF ??!!
Yes (Coinseeker has the same)
-U13 has only one gate used , i suppose unused pins are left unconnected .
Yes
-I dont think i will be able to make it single side, but i will try to keep this as an option ,that can be compensated by wirings.
Personally i have not problem if it is a double side pcb
-I will assume that the inductor connected in serie with the RX coil is the size of a 0,5W resistor.
I believe that it is enough

If you have any comment on this or other part please let me know.

Regards!,
Fred.

Hi Fred.
I did not find errors yet. So i wish you good luck with the pcb.
I am sure about the quality of your pcb drawing
Regards

[Fred]

Hi,
Thanks for answers!
I am beginning the PCB.
Some observations:
-The capacitor in // with the TX coil is 1uF ??!!
-U13 has only one gate used , i suppose unused pins are left unconnected .
-I dont think i will be able to make it single side, but i will try to keep this as an option ,that can be compensated by wirings.
-I will assume that the inductor connected in serie with the RX coil is the size of a 0,5W resistor.

If you have any comment on this or other part please let me know.

Regards!,
Fred.

[Max]

Hi Max,

Don´t you think the lack of regulation could be a problem for the oscillator stage?

Regards,
Fred.

Hi,
no, I think oscillator little variations are not so important... also the oscillator here is different from e.g. Tesoro's that employ very classic configuration of colpitts' one. Geo is probably right that phase variations will be very small comparing RH with other designs.

I will be not surprised of very hi stability on lead-acid cells... like happens with some PIs too that have unregulated 12V rail. I think the interesting part of circuit is, apart oscillator stuff, the op amp chain... preamp+integrators other things , though essential are really close to other designs and so not better than that.

I think RH will have at least same , but probably more stability that a very good homemade TGS an no chatters at all.

The fact ML decided not putting 12V regulator there let me think it's absolutely unuseful in such a design.

I don't know about detph comparision but seems to me the osc stage will play important role, so probably good gain, over tesoro's designs on same coil dimensions... real data we could collect just making it!

Kind regards,
Max

[Geo]

Hi Max,

Don´t you think the lack of regulation could be a problem for the oscillator stage?

Regards,
Fred.

Hi Fred.
With the unregulated voltage we will have a small frequency shift (when voltage is low) but i think that the phase shift will be stable (at large degree).
Regards

[Fred]

Hi Max,

Don´t you think the lack of regulation could be a problem for the oscillator stage?

Regards,
Fred.

[Max]

+VCC=+12V unregulated...
Fred.

Hi,
yes, unregulated... but is not a big problem in this case... cause op amps used have large immunity from such problems...like slow supply variations I think that with a fully charged 12V lead-acid battery you'll never find circuit unstable cause of voltage variations.

The 27Mx is really stable thing and have not much troubles dealing with slow variations at supply rail... the CMOS stuff will be also really stable too and good for the purpose.

Sure... if you use some small cells pack you could be lost into troubles... but I think this is not a real problem too... you could e.g. use a couple of cells more and then a regulator for 12V like 7812.

Actually I think RH have really more consistent stable approach than many other circuits we saw already.

Kind regards,
Max

[Fred]

Hi,just cause seems a bit tricky for some of us... Max

+VCC=+12V unregulated...
Fred.

[nakky]

RH

Thanks Max,this is also my problem,I am not technical,I can only COPY.Grt Nakky.

[Max]

Hi,
just cause seems a bit tricky for some of us... I decided posting a picture of what I expect for voltages at the 5 rails using GND as reference.

Any dubt ? Let me know...

Kind regards,
Max

[Max]

Hi,
to make things more clear, there are 5 rails on RH schematic:

1) + or +Vcc (different names for same thing)
2) - or -Vee (different names for same thing)
3) GND , that's ground rail (with large mA load ability cause of buffering)
4) -2.5V at LM336 , that's only reference voltage
5) +2.5V at op amp out, that's complementary reference voltage

As you can see +,- are for supply, GND is reference GND level for op amps operations, and +2.5/-2.5 are reference used to e.g. pots as VERY stable (compensated) voltage refs.

Here is revision 1.2 with all that stuff in magenta color.

Kind regards,
Max

[Fred]

Ok Max, thanks.

I prefer schematics whith common +/ov/- rails , this one is not so clear to make a PCB from...

What i meant is that i prefer common supply rails drawn on the schematic.
Just an observation, no matter here...

see you,
Fred.

[Max]

Hi,
Can you confirm that Max´s "-vee" is the same as the "-" on schematic? seem logical but ...that´s 3 negatives supplies, "-2,5" , "-" , and "-vee " .
I prefer schematics whith common +/ov/- rails , this one is not so clear to make a PCB from...
Regards,
Fred.

Hi Fred,
the -2.5V at LM336 is reference voltage only ... used by some op amps so doesn't give real power to circuits: notice that it's 2.5v from negative potential value (reference potential).

The "-vee" I use is the same as "-" : I use that terminology cause often employed with op amps etc not cause it's different voltage.

Actually the "-" voltage is connected to the negative of battery: that's cause the GND potential is generated actually by op amps... look at the one that has 100ohm on output (part of the quad op amp ic) and you'll find it.

That's old trick to generate GND potential with enough current/power from single voltage operations.

PS: Fred if you try make PCB remember decoupling caps , 2 for each ic, 100nF

Kind regards,
Max

[Fred]

Hi,
Can you confirm that Max´s "-vee" is the same as the "-" on schematic? seem logical but ...that´s 3 negatives supplies, "-2,5" , "-" , and "-vee " .
I prefer schematics whith common +/ov/- rails , this one is not so clear to make a PCB from...
Regards,
Fred.

[Fred]

Hi,
Ivconic told you: it's inductor stuff for audio stage thing... I think cause it's very unlike we can find suitable replacement of same size/terminals etc we can make there just two pads and then connect the thing required (any shape) with leads... just we have to remember to leave some extra space for stuff that require more room there (nucleus etc).
Max

Hi Max,
Yes this is important to remember, i think tthere is no other "tricky" part...
I don´t exactly understand the real purpose of this inductor, probably some filter/impedance matching circuit,a jumper or resistor should work for testing purposes...
See you,
Fred.