TESORO GOLDEN SABRE

[simonbaker]

R5

Hi Ivconic:

Just noticed last schematic has two "R5" resistors at speaker, needs relabel.

Also, is the 330 ohm "R5" at the collector of TR3 important? What happens if not there?

Comparing to original TGSL schematic, interesting to see no JFet feedback path on TX oscillator -- must not be important after all. Also we have new supply filter capacitor C3 at +8v output of LM7808, like on Molzar PCB.

One more idea for experimenters -- remember original TGS (Molzar PCB) did not have diode D11.

Cheers,

-SB

Correct. I made mistake. Must remind you that English language is not my native language. So many times i made simillar mistakes; wanted to point on something else but wrote something quite inproper instead!? Ha,ha,ha!!!
Sorry and please understand my situation.
Regards!

Hey, I wasn't trying to put you down. You're the teacher here. I just have better command of the English language. (My former English teachers might take issue with that.) Now, if you had to read me as I tried to explain anything in a language other than English, then you might not know whether to laugh or cry. It would be very difficult.

I don't know everything, but I thought I knew the answer to SB's question. I responded, but maybe I should have stayed home?

Anyway, good work on your TGSL! I especially like your speaker driver, it looks very efficient.

[ivconic]

Values...

[ivconic]

Look on posted photo of pcb, blue circles (elipses)...
Also i am preparing better pic with components values...

[simonbaker]

Correct. I made mistake. Must remind you that English language is not my native language. So many times i made simillar mistakes; wanted to point on something else but wrote something quite inproper instead!? Ha,ha,ha!!!
Sorry and please understand my situation.
Regards!

You communicate in more than one language, better than me!

Can you show the decoupling caps on the schematic too for helping us understand your improvements?

Best regards,

-SB

[ivconic]

"Coupling capacitor" is a misnomer. More correct would be "decoupling capacitor". Or, "supply bypass capacitor". They are absolutely essential in circuits that use many digital IC (at high speeds) and become less important at lower frequencies. Think of them as preventive medicine.

They are usually placed near to IC supply pins (especially on digital IC), to provide for instantaneous current demands - keeping the supply voltages smooooth. A good plan is to use the usual big power supply cap and spread some small decoupling caps around. Small caps -should- have a lower impedance at the high (switching) frequencies than large electrolytics will.

(Coupling capacitors are used between different stages of an audio amplifier (or an RF amplifier, for example) to couple the signal but at the same time maintain isolation of DC voltages in the various stages.)

Correct. I made mistake. Must remind you that English language is not my native language. So many times i made simillar mistakes; wanted to point on something else but wrote something quite inproper instead!? Ha,ha,ha!!!
Sorry and please understand my situation.
Regards!

Hi Ivconic:
... can you explain "coupling capacitors" (.1uF) more? Did you put them on PCB or schematic? What is function?
-SB

"Coupling capacitor" is a misnomer. More correct would be "decoupling capacitor". Or, "supply bypass capacitor". They are absolutely essential in circuits that use many digital IC (at high speeds) and become less important at lower frequencies. Think of them as preventive medicine.

They are usually placed near to IC supply pins (especially on digital IC), to provide for instantaneous current demands - keeping the supply voltages smooooth. A good plan is to use the usual big power supply cap and spread some small decoupling caps around. Small caps -should- have a lower impedance at the high (switching) frequencies than large electrolytics will.

(Coupling capacitors are used between different stages of an audio amplifier (or an RF amplifier, for example) to couple the signal but at the same time maintain isolation of DC voltages in the various stages.)

[ivconic]

Yes those are.
I will prepare .lay with values. I used to observe schematic and printed pcb mutualy during soldering components (very good method - twice the accuracy - double checking) , that's why i didnt write values. But if that will help you more; i will prepare and repost it again.

[simonbaker]

I suppose the coupling capacitors are on the solder side of the board, but what location are those ? Perhaps they are the reason for the calm operation of the deviced + the bigger GND ring around the board outline.
Yup there are no labels on the board, would be good to have them labeled, the board is very nice, small size could fit to many small md boxes, hmm perhaps I should try it

I guess he is saying "decoupling capacitors", or bypass capacitors, maybe across rails or certain supply pins of ICs to suppress high-freq noise, like voltage spikes, etc. I found some useful places to put them on my proto-board TGSL, but wondered if needed on actual PCB.

It sure is nice looking board, thanks to Ivconic many experiments and designs.

Cheers,

-SB

[eclipse]

I suppose the coupling capacitors are on the solder side of the board, but what location are those ? Perhaps they are the reason for the calm operation of the deviced + the bigger GND ring around the board outline.
Yup there are no labels on the board, would be good to have them labeled, the board is very nice, small size could fit to many small md boxes, hmm perhaps I should try it

[simonbaker]

Huh, to much fuzz here, without such need!?
There are NOT "uneeded" resistors there? Who give you such idea? Those resistors there prevents opamp's inputs and output to flow. So keep those there.
I think i already posted my final (and best) work on this subject!? I am not sure (lazy to search back the pages). So i am posting complete final work again here. You have here all you need to complete device. No mistakes. Works perfect. You have schematic and .lay file here. Enjoy!

P.S.
There are coupling capacitors (0.1uF) at major points (according to my humble opinion) that must be coupled.
No monostable mod in this last version; simply no need for it. Monostable can provoke some instability, so i decided and left that idea. Further, audio is modded and boosted a bit with much better solution, no need for monostable at all.
This is FINAL version, most accurate and best so far. No need for further confusing about this subject.

Hi Ivconic:

Thanks for latest design. But ".lay" file does not seem to have component values labeled. Do you have another file with labels?

Also, can you explain "coupling capacitors" (.1uF) more? Did you put them on PCB or schematic? What is function?

Regards,

-SB

[eclipse]

Thank you ivconic you are always so helpfull, we really appriciate your efforts!

[simonbaker]

Huh, to much fuzz here, without such need!?
There are NOT "uneeded" resistors there? Who give you such idea? Those resistors there prevents opamp's inputs and output to flow. So keep those there.
I think i already posted my final (and best) work on this subject!? I am not sure (lazy to search back the pages). So i am posting complete final work again here. You have here all you need to complete device. No mistakes. Works perfect. You have schematic and .lay file here. Enjoy!

P.S.
There are coupling capacitors (0.1uF) at major points (according to my humble opinion) that must be coupled.
No monostable mod in this last version; simply no need for it. Monostable can provoke some instability, so i decided and left that idea. Further, audio is modded and boosted a bit with much better solution, no need for monostable at all.
This is FINAL version, most accurate and best so far. No need for further confusing about this subject.

Great, much appreciated!

Also, good point about "unneeded resistors". A question I have been meaning to ask was whether inputs and outputs of unused op amps can be floating or should be "tied off" somehow to prevent oscillations or other effects. I know some components need it, but not sure with op amps.

So, if that's the case, sorry for bad advice -- Ivconic says keep resistors R48, R49, R50, R51 (connected to LM358 U107b) even if not using battery check circuit.

Cheers,

-SB

[ivconic]

"..Monostable can provoke some instability.."
Actually monostable cant do that. But monostable input is so sensitive, it can be switched On by slitest hum from previous stage. Pitty. I experienced huge "instabillity" and lot of falses on real soil. To overcome the problem, coil must be hold 10-15cm away from soil surface - which is huge drawback...logically..
So... trying this and that...finally i decided and left that idea.
Other hand, new audio applied on last version is real bijou! I am very satisfied with it! Works fantastic. You must try to see!
This last version became my working detector and aproved itself several times in last 3 months. So stabille i cant explain!? It is calm, silent and stabille that much - in the begining i checked many times if device is switched On?! With no metal in soil i can walk 200-300 meters with no sound at all, no hum, no nothing....silent as a fish!
When detects something, audio is strong,soft and rich...also target depth&size&type dependable...just what i always wanted!
But pay attention on BD140 there. Must be a kind. I checked many simillar transistors and all those are not working the same. By trial&error i found out BD140 as most suitable, giving most pleasant tone.

[ivconic]

Huh, to much fuzz here, without such need!?
There are NOT "uneeded" resistors there? Who give you such idea? Those resistors there prevents opamp's inputs and output to flow. So keep those there.
I think i already posted my final (and best) work on this subject!? I am not sure (lazy to search back the pages). So i am posting complete final work again here. You have here all you need to complete device. No mistakes. Works perfect. You have schematic and .lay file here. Enjoy!

P.S.
There are coupling capacitors (0.1uF) at major points (according to my humble opinion) that must be coupled.
No monostable mod in this last version; simply no need for it. Monostable can provoke some instability, so i decided and left that idea. Further, audio is modded and boosted a bit with much better solution, no need for monostable at all.
This is FINAL version, most accurate and best so far. No need for further confusing about this subject.