GOLDSCAN 5 SCHEMATIC QUESTION

[Idefix]

@idefix
Those are power resistors. One is 2 ohm 25w and the other is a 1k 15w. The 2 ohm limits the coil current. It replaced the lm337 and allows the use of ml coils

Ok.
Many thanks again for this job. Everybody.

TDI PRO :
Sheet demodulator, R31 2.2M , not 2.2m -- only for update.
Sheet timing : Delay Pot Value not indicated. (10K ? )

Sheet TX Preamp. The TDI uses 3 diodes 1N4148, and 2 are in parallel . It is necessary to have many diodes to avoid risks . With 500V flyback voltage, and 1K, the current surges to 500mA, it is too much for one diode, even during short time. So SS22 is a shottky 2A average, 75 A surge.

Sheet demodulator. May be an improvement is to to wire a 1NF on the wipers of the 50K trim ( trim between R12 R13, and Trim between R17 R18 ) This will avoid some noise going from the suplies to OP Amps. This is only to improve noise filtering .
Also I think CD4001 system is a Power-on Shut UP. (but I m not sure of the way to call it). Squelch on power-on ?


Great job again.

[6666]

Hey Altra just a question on your schematic, what would be your guess as to why both D2 and D3 are there in parallel ?

[6666]

Great work Altra, Jose and others.

[Altra]

@idefix

Those are power resistors. One is 2 ohm 25w and the other is a 1k 15w. The 2 ohm limits the coil current. It replaced the lm337 and allows the use of ml coils

[dbanner]

Ah yes. I'm just now seeing the pic of the board you posted, it shows LT1112. Again, thanks for all the great pics and schematics, I think i've got enough for a successful build.

[Jose]

I am looking at the different schematics, but what is the file to be checked ?

On the picture you sent, in the upper left part of the board , near the MOSFET, there are the two regulator LM337. ( TO220 Packaged )

For Jose, in the GSX5JB, you don't use current limitation in the MOSFET, and the other will appear in other part of the schematic I guess ?

The scheme that I published, is for the purpose of observing the corrections I made, because the Turkish scheme had some errors, especially the synchronization of the time base with the integrators, capacitors and resistors of the integrator, the reset circuit, during the ignition of the detector, and other minor details.
This scheme works well, but it was taken as a basis of the Turkish scheme and some photos of the GS5.
Also I do not use the current limiter and make other modifications to use it with 12 volts.
However, the schemes published by Altra, were taken from one of the first TDIs manufactured, and I think we should follow in their footsteps.
In addition, as Altra said, we can consult you if we have any questions.
Jose

[Altra]

I am looking at the different schematics, but what is the file to be checked ?

On the picture you sent, in the upper left part of the board , near the MOSFET, there are the two regulator LM337. ( TO220 Packaged )

For Jose, in the GSX5JB, you don't use current limitation in the MOSFET, and the other will appear in other part of the schematic I guess ?

Post #214 pdf

[Altra]

The schematic posted by Altra(TDI PRO PROTO) shows 47 ohm resistor between U2A pin 1 and what should be U2B pin 5 (TLC2262). It should be 47K. Also the 100nF capacitor between U2B pin 6 and 7 should be 47nF. The GSX5JB also shows this cap as 47nF. The picture of original Goldscan 5 board shows a 47nF capacitor. That's just my observation.
Thanks to Altra and jose for posting these schematics, will be very helpful.

They are slightly different circuits with different pcbs. I posted a photo of the main TDI pcb you will not find a 47nf or a TLC2262. Build Jose's tested GS5 frontend and use the drawings I posted for ideas on the audio.

[Idefix]

Eclipse is correct about the integrator inputs reversed. The integrator is a TL062, the next 4 amps same page are a quad lt1114. The audio gain stage is a LT1112. A quad TL064 is used for the absolute amplifier with one of the amps unused. I drew this for reference not to clone. If people find something they question circle it on the schematic and post. I will try to verify.

I am looking at the different schematics, but what is the file to be checked ?

On the picture you sent, in the upper left part of the board , near the MOSFET, there are the two regulator LM337. ( TO220 Packaged )

For Jose, in the GSX5JB, you don't use current limitation in the MOSFET, and the other will appear in other part of the schematic I guess ?

[dbanner]

The schematic posted by Altra(TDI PRO PROTO) shows 47 ohm resistor between U2A pin 1 and what should be U2B pin 5 (TLC2262). It should be 47K. Also the 100nF capacitor between U2B pin 6 and 7 should be 47nF. The GSX5JB also shows this cap as 47nF. The picture of original Goldscan 5 board shows a 47nF capacitor. That's just my observation.
Thanks to Altra and jose for posting these schematics, will be very helpful.

[Jose]

Does he alter iron tone „instantly“ after crossing above the iron target ?Does it work on 3khz and what is the width of the pulse ? Thank you Nenad !

Yes, high and low tones change rapidly when passing metals of different conductivity.
Press width TX use 100 useg.
The frequency, 3; 3.2 Kz
Sample 15 useg. separated 100 useg for the second sample.
Identical GB channel, the separation between both channels is 20 useg.
The points marked A, B, C, D, in my scheme, they have no relation to the Turkish scheme.
Jose

[Jose]

Hi

Many thanks for these posts. Very usefull.

Jose, about the GSX5JB, your drawings looks like using the CadStar CAO. Is it ?

It's DipTrace.

[Jose]

I noticed you put D7 a normal silicon diode. It should be a Schottky. Its function is to prevent JFETs gates from conducting when forward biassed. Trouble with JFETs is that a gate-channel barrier is lightly doped, so the gate-barrier diode forward voltage is lower than that of normal silicon diodes, and therefore a normal diode can't prevent JFETs from conducting in this configuration. Try BAT85 instead.

Thank you Davor for the observation, in all the diodes use 1N4148, I will replace them as soon as I get those diodes.
Jose

[Altra]

Eclipse is correct about the integrator inputs reversed. The integrator is a TL062, the next 4 amps same page are a quad lt1114. The audio gain stage is a LT1112. A quad TL064 is used for the absolute amplifier with one of the amps unused. I drew this for reference not to clone. If people find something they question circle it on the schematic and post. I will try to verify.

[Orbit]

I'm completely confused dbanner so far he is looking for the diagram GS 5 and now it shows photo GS 5 ?!!