IGSL

[Davor]

As I bragged already - my IGSL PCBs came today so I can start with trial and error engineering

A little bit on spice: it is a tool. And a good one. No real world component will give up smoke if you overdo something in spice, but a ton of surprises may come upon your precious little thing in a real world. That's for sure.

Now a look from completely different perspective. I used spice to explain myself, and everyone else with a shared interest who cared enough to fire up my sims - what exactly happens there. And what can be done to make it work better if possible. For example, I found that names for disc sens and threshold functions are in fact mutually exchanged: sens works by means of setting a threshold to trigger a comparator, while threshold trimmers actually control audio sensitivity or how loud a response will be.
I also found out the role of diodes in feedback paths of gain blocks, and a possible source of chatter - I'll try it first in vivo to be sure.

I also found out that the whole discrimination business is a 2 quadrant thing. I can live with that. It explained me the importance of connecting Rx loop in a proper polarisation to receive one beeeeeeep instead of two short beep ... beep which happen at phase reversal of a motion compensation filter.

Now I can start building my first MD with ease and competence. I can say I truly understand every bit of it.

[Qiaozhi]

Btw generaly simulating software is good for circut that can't be distracted from outside influence, for simulating let's say one PIC mcu it is not bad to use simulating software, you can put you'r pic under the power lines and he will work just fine, jus't like in let's say proteus isis and it is ok.
But make one metal detector in spice or any kind of simulation software and put detector below power lines, detector will work like mad LOL.
Can any of you simulate outworld influence?
Lets say EMI?
Maby spice work just fine but in space.!
I hope i didn't insult anyone if i am i publicly apologize!
Cheers
Detecto

The important thing is to make sure that your Spice simulation and the real world behaviour of the circuit match each other. You must also be aware of component tolerances when running Spice. It is very easy to design a circuit that simulates 100% correctly, but when it actually comes to building it, only [for example] 50% of the units may actually work properly. Remember to run a Monte Carlo analysis in order to get the correct tolerancing, or for some circuits a Worst Case and/or Corner Case analysis.

At the end of the day, there's no substitute for knowing what you're doing.

[detecto]

Btw generaly simulating software is good for circut that can't be distracted from outside influence, for simulating let's say one PIC mcu it is not bad to use simulating software, you can put you'r pic under the power lines and he will work just fine, jus't like in let's say proteus isis and it is ok.
But make one metal detector in spice or any kind of simulation software and put detector below power lines, detector will work like mad LOL.
Can any of you simulate outworld influence?
Lets say EMI?
Maby spice work just fine but in space.!
I hope i didn't insult anyone if i am i publicly apologize!
Cheers
Detecto

[detecto]

Detecto you are right and i agree with you 100%.
But beware of some ultimate DSP experts here!
If you continue to think and post such (correct) things you are at great risk to be proclaimed as : "Trial&Error "engineer" " !!!

Look:

".....//*LOL* (Regarding the debate)
Please Davor, keep on kicking to the "trial & error" - "engineers".
I love your spice simulations and your fresh way of thinking.
Keep up the good work.
Cheers,
"Ultimate DSP expert" ...... "

Now you know why i hesitate to post anything more on this topic! I simply don't dare!
I will rather post irrelevant stuff in Off Topic part from now on...

I appreciate Davor work in spice, but dear Davor before spice (and other simulating software) invented people are improved much more complex circut than IGSL.
I don't have anyting abouth using spice,
but many "working circut" in spice don't keep water in real world
Don't be mad on me Davor i don't have anything about your spice simulations but keep on mind many "working circut" in spice don't keep water in real world
For
-Davor
best way for improvement is GET THAT SCOPE from basement :P

For
- Ivconic
don't take to heart dose words such as "trial & error" - "engineers".

For
-dude why write "trial & error" - "engineers".
Dude you must understand that on collage easiest way for profesor is to make some circut in spice, isis, EWB etc etc and say to students this circut work like this, and for this circut is important this and this.... THIS IS BAD WAY!
I have a lot of friend's from collage who don't make difference between caps, resistors and diodes major problem is that damn spice :P
Btw you shuldn't say "trial & error" - "engineers , those your "trial & error" - "engineers
making improvements in real world.
and "new and digital" engineers can calculate 2+2=5 ofcourse in isis,spice.... (Davor don't find yourself here i don't speek abouth you)
If anyone need to choose between "trial & error" - "engineers and "new and digital" engineers you can free choice "trial & error" - "engineers, and you don't make a mistake if you make a mistake blame on me
Cheers
Detecto

[ivconic]

Detecto you are right and i agree with you 100%.
But beware of some ultimate DSP experts here!
If you continue to think and post such (correct) things you are at great risk to be proclaimed as : "Trial&Error "engineer" " !!!

Look:

".....//*LOL* (Regarding the debate)
Please Davor, keep on kicking to the "trial & error" - "engineers".
I love your spice simulations and your fresh way of thinking.
Keep up the good work.
Cheers,
"Ultimate DSP expert" ...... "

Now you know why i hesitate to post anything more on this topic! I simply don't dare!
I will rather post irrelevant stuff in Off Topic part from now on...

[detecto]

Btw instead 78L08 much better replacement will be LM2930-8
less current consumption, also there is much better op amps with less current consumption.
And audio part in IGSl can be done with one dual timer like NE556 (ivconic alredy say this somewhere else.)
Regards
Detecto

[detecto]

If you want to improve IGSL, best way is to get one working IGSL, Scope, multimeter, etc...etc....etc
More capacitance here les resistance there, better op amp here...
and improvements will be achieved
Qiaozhi is right abouth spice.
Personally i don't believe in any simulation software.
I posted somewere here picture with hi and low pass filters, and i believe that they are reason for unstabile work of any TGSl detector when you increasing sens over 90%
Regards
Detecto

[ivconic]

Why bother with toys?
(Before someone attacks me: I also meant the "top performers" a la market leaders babies.)

Aziz

It's ok! Don't hesitate to say anything you want! It's alright!

[Aziz]

Because I wish to maintain incremental changes approach. Completely radical would be using a Costas loop.
Besides, who'd say a sexy lock in amplifier wouldn't suffer from some unforeseen glitches. Like that chatter thing for example.

You'd be able to check many more options with your soundcard rig and a few algorithms.

Why bother with toys?
(Before someone attacks me: I also meant the "top performers" a la market leaders babies.)

Aziz

[Davor]

Because I wish to maintain incremental changes approach. Completely radical would be using a Costas loop.
Besides, who'd say a sexy lock in amplifier wouldn't suffer from some unforeseen glitches. Like that chatter thing for example.

You'd be able to check many more options with your soundcard rig and a few algorithms.

[Aziz]

I have no idea about that, but I'll try different frequencies now that my PCB's came

I don't have any coils so far and I'm not committed to any particular flavour so far. Hence, I might raise or lower the frequency as I wish. I have some AWG 20 wire at hand so it'll probably be higher rather than lower.

From what I've seen the most (if not all) of the VLF MDs with discrimination are 2 quadrant phase detectors, and that narrows my options a bit. A full 4 quadrant rig would be capable of employing some different but simpler IB coil schemes. Phase reversal would mean finding the same target at the opposite side of the same diagonal (in the opposite quadrant), but alas - that quadrant is rejected.

Phase detector in IGSL, TGSL, Cobra, etc. is made with analogue AND circuitry (comparators), and 4 quadrant would require analogue XOR. If I manage to tinker and squeeze such a device into the existing concept - I'll let you know.

Why don't you use a lock-in amplifier?

Aziz

[Davor]

I have no idea about that, but I'll try different frequencies now that my PCB's came

I don't have any coils so far and I'm not committed to any particular flavour so far. Hence, I might raise or lower the frequency as I wish. I have some AWG 20 wire at hand so it'll probably be higher rather than lower.

From what I've seen the most (if not all) of the VLF MDs with discrimination are 2 quadrant phase detectors, and that narrows my options a bit. A full 4 quadrant rig would be capable of employing some different but simpler IB coil schemes. Phase reversal would mean finding the same target at the opposite side of the same diagonal (in the opposite quadrant), but alas - that quadrant is rejected.

Phase detector in IGSL, TGSL, Cobra, etc. is made with analogue AND circuitry (comparators), and 4 quadrant would require analogue XOR. If I manage to tinker and squeeze such a device into the existing concept - I'll let you know.

[golfnut]

IGSL IDX

(Firstly thx Dave and Bob got your payment.. )


With The IDX and IGSL they are first order the same 'type' of machine.

Similar Architecture etc .

One of them seems deep on chunky coins and is easy to make coils for and tune up.

One of them is not so deep generally and is more difficult to make coils for and tune up.


The main delta between them is frequency 6.5kHz and 14.5kHz

Are high frequency machines generally more tetchy to make, align, use, on european soil.

Steve

[simonbaker]

It is very same as the first untouched one, with only difference of stepped GEB channel signal (to show the difference). Here you are...
Once you are playing with it try increasing the threshold pot Rtot.

Yes, I agree with your conclusion that the feedback RC dominates, and looks like we could dump those other caps and 1 meg resistor, which is a useful find, thanks! I'm not experienced enough to know if those parts were intended to help with some real-world glitch of some kind...

-SB

[Davor]

Hi Davor:

Would you post the LTSpice file for this latest sim?

-SB

It is very same as the first untouched one, with only difference of stepped GEB channel signal (to show the difference). Here you are...
Once you are playing with it try increasing the threshold pot Rtot.