TL12000

[haylaz0036]

I recently built a new TL12000 circuit. Here is the video of it. Unfortunately, I swapped the titles of the two videos. Based on conductivity, it rejects iron better than other pulse-induction metal detetors
https://www.youtube.com/shorts/T_gpkqXyZcY
https://www.youtube.com/shorts/EA3SoBjp70w

Dear Asanka, the video is excellent. I tried this before but couldn't get the discrimination feature to work; after seeing this video, I want to try it again. I would really appreciate it if you could provide the links for the schematic/PCB layout I should use.

[haylaz0036]

Hi ASDF12345,

Here is the TL12000 Diptrace schematic file. Enjoy...

[ATTACH]n442407[/ATTACH]

Dear Geomax, I was unable to open the file you provided; could you please send it as a PDF?

[GeoMax]

Dear Geomax, I was unable to open the file you provided; could you please send it as a PDF?

Here is the PDF...

TL12000 PI Detector Rev1.0.pdf

[haylaz0036]

Dear Geomax, thank you very much. I wonder, what is the difference between this one and your other schema?

[haylaz0036]

I wonder if there is a PCB for this?

[GeoMax]

Hello,

No, there is no PCB for this schematic. I created it solely for study purposes to get a better overview of the many variations circulating online. Also, please note the information in the bottom right corner of the schematic.
If you like, you can design a PCB and publish it here on Geotech.

[haylaz0036]

Have you watched Asanka's videos? The discrimination works really well.

[Asanka Sanjeewa]

Dear haylaz0036
Here is the information you requested:
For the all-metal mode, set the variable resistor connected to the CD4013 to the 100k level.
The easiest way to achieve iron rejection is to remove the variable resistor and replace it with a 56k resistor or a 47k resistor [ if the 56k does not work]. 56k - 47k resistor will reject iron [provided your coil values are correct].

[Asanka Sanjeewa]

Important Points
Disconnect pin 4 of the second 555 timer circuit from its current (incorrect) connection and connect it to 18V.
Since excessive voltage can damage the circuit, supply power to the circuit via a 7818 regulator equipped with a heat sink.

Use only the version of the BU508 transistor [ BU508A ] with the suffix 'A'.

To effectively achieve iron exclusion... PLEASE USE 0.50MM THICK COIL AND COIL INDUCTANCE OF 440 MICRO HENRY [ I USED 30CM DIAMETER ROUND, 21 TURNS, 0.50MM THICK COIL ] AND USE MULTITURN POT.METER FOR 20K VERIABLE RESISTOR [ TUNING POT. ]
SET THE FREQUENCY 400Hz

[GeoMax]

Important Points
Disconnect pin 4 of the second 555 timer circuit from its current (incorrect) connection and connect it to 18V.
Since excessive voltage can damage the circuit, supply power to the circuit via a 7818 regulator equipped with a heat sink.

Use only the version of the BU508 transistor [ BU508A ] with the suffix 'A'.

To effectively achieve iron exclusion... PLEASE USE 0.50MM THICK COIL AND COIL INDUCTANCE OF 440 MICRO HENRY [ I USED 30CM DIAMETER ROUND, 21 TURNS, 0.50MM THICK COIL ] AND USE MULTITURN POT.METER FOR 20K VERIABLE RESISTOR [ TUNING POT. ]
SET THE FREQUENCY 400Hz

Hi Asanka,

Why do you think the connection at pin 4 is wrong? The connection pin 4 of the second 555 timer is there to synchronise the charge pump only.

[samir3]

Important Points
Disconnect pin 4 of the second 555 timer circuit from its current (incorrect) connection and connect it to 18V.
Since excessive voltage can damage the circuit, supply power to the circuit via a 7818 regulator equipped with a heat sink.

Use only the version of the BU508 transistor [ BU508A ] with the suffix 'A'.

To effectively achieve iron exclusion... PLEASE USE 0.50MM THICK COIL AND COIL INDUCTANCE OF 440 MICRO HENRY [ I USED 30CM DIAMETER ROUND, 21 TURNS, 0.50MM THICK COIL ] AND USE MULTITURN POT.METER FOR 20K VERIABLE RESISTOR [ TUNING POT. ]
SET THE FREQUENCY 400Hz

Show this as picture

[samir3]

عن توصيله الحالي (غير الصحيح) وقم بتوصيله بجهد 18 فولت.

نظرًا لأن الجهد الزائد قد يُتلف الدائرة، قم بتزويد الدائرة بالطاقة عبر منظم جهد 7818 مزود بمشتت حراري.

Show. In picture

[GeoMax]

Dear Geomax, thank you very much. I wonder, what is the difference between this one and your other schema?

Which difference do you mean? I posted a PNG image file at one point, and a PDF of that PNG file at another; someone had asked for it because they couldn't open the DipTrace schematic. The only difference is the file format. Everything else is the same.

[haylaz0036]

Important Points
Disconnect pin 4 of the second 555 timer circuit from its current (incorrect) connection and connect it to 18V.
Since excessive voltage can damage the circuit, supply power to the circuit via a 7818 regulator equipped with a heat sink.

Use only the version of the BU508 transistor [ BU508A ] with the suffix 'A'.

To effectively achieve iron exclusion... PLEASE USE 0.50MM THICK COIL AND COIL INDUCTANCE OF 440 MICRO HENRY [ I USED 30CM DIAMETER ROUND, 21 TURNS, 0.50MM THICK COIL ] AND USE MULTITURN POT.METER FOR 20K VERIABLE RESISTOR [ TUNING POT. ]
SET THE FREQUENCY 400Hz

Dear Asanka, I tried this PCB before, but unfortunately, I couldn't get the discrimination feature to work. I couldn't find an LM709; could that be the reason?

[Asanka Sanjeewa]

Dear Geomax
I tested two mathod. But much better and stable for supply 18 volts of 4 pin 555 ic