Bulgarian 'PULSE STAR' (... close to Legendary one)

[Geo]

All consumers OF !!, all the TV off, only oscilloscope ON! Coil diameter of 20 ....... 30 cm, no more !!!!! In the workshop has great noise. Adjustment see post # 124 , NE 5534 pin1 ,pin5 capacit. 5pf....10pf. POWER SUPPLY BATERY!!
pulse width of 150 ... 200 micr. sekunds , no mor!!

Hi Georgi.
Coil is 25cm diameter,280uH. Pulse width is 180us.
Power supply is not from battery. I will try to charge some batteries.
I have a capacitor 10pF betwen pin 1 and 5. Why when i close the discrimination potentiometer i lose the adjustments of RV7,87,9???
At who position i must have this potentiometer (discrimination)??. This time i have some problems. When i will solve then, the detector will be about the same with TDI!!!

Regards

[georgi.g.zhelev]

Hi Georgi.
One more question...
When i adjust the trimmers RV7,8,9 at who position i must have the Disc potentiometer???. I saw that when i change it, it destroys the adjustments.

Regards

All consumers OF !!, all the TV off, only oscilloscope ON! Coil diameter of 20 ....... 30 cm, no more !!!!! In the workshop has great noise. Adjustment see post # 124 , NE 5534 pin1 ,pin5 capacit. 5pf....10pf. POWER SUPPLY BATERY!!
pulse width of 150 ... 200 micr. sekunds , no mor!!

[Geo]

Hi Georgi.
One more question...
When i adjust the trimmers RV7,8,9 at who position i must have the Disc potentiometer???. I saw that when i change it, it destroys the adjustments.

Regards

[Geo]

I had a mistake at the schematic of power supply.
Look this....

[Geo]

Hi Georgi.
Here is a photo of the output of 5534. Look the ripple!!!!
I supplied the +8,-7V from the lab power supply but no results.
I will try to connect a capacitor on pin4 and pin7 of 5534.
Any other idea???

Regards

[Geo]

Hi Georgi.
I attach the schematic of the power supply.
If you like the waveform at the diodes then i will adjust the trimmers today and i will tell you.
At the output of the 5534 i have much noise. I will try to take a photo later. Another problem is the bad stability. When i press the buton the detector has a "good" depth but after 1..2 minutes it loses it....

Regards

[georgi.g.zhelev]

PS

Geo, your power supply, please show shematic.Diodi1N4148 work great. NE5534 .. pin 6 - 0.2v, adjusted with trimmer!


PLEASE SHOW ALL YOUR PLAN OF PULS STAR.

[Geo]

NE5534 ..... trimer .... pin 6 ....- 200mv; COIL .... 350 .... 500 mikr.H, r = 0.7 ....... 1.2 ohm; changes NE5534 ; changes 1N4148; R parallel to the coil (damper) 200 ..... 270 Ohm. check board scheme!! g.l.!

Hi George.
The second waveform is at D21... D22 (1N414 with the NE5534 out of the socket.
Coil is 280uH, r=1.5Ohm. I had one 1n4148 failed, i replaced both diodes but again the same. Damper is 240R and the board is OK.
Now without to adjust the trimers it locate a soda can at 40...45 cm with full discrimination and a coin 30mmm at 25cm. But i see that it is not OK. The second probe shows 530V on the drain of the IRF740, so it is more near to you. But there is problem at the diodes, there the signal must be 0.6...0.7V but at my detector it is 1.2V (the peak). So i need a better diode, maybe more fast. The down side of the pulse is OK (0.7V).
Any idea??

Regards

[georgi.g.zhelev]

PS

NE5534 ..... trimer .... pin 6 ....- 200mv; COIL .... 350 .... 500 mikr.H, r = 0.7 ....... 1.2 ohm; changes NE5534 ; changes 1N4148; R parallel to the coil (damper) 200 ..... 270 Ohm. check board scheme!! g.l.!

[Geo]

Hi Georgi.
I replaced the coil with another (280uH) but i have the same problems. I attach two photo. One from the Drain of MosFet and the other from the input of NE5534. This is very bad.
What are you say? I took out the 5534 but the waveform remains the same. I will replace the 1N4148..... maybe...Also i replace the dumper without any results

Regards

[Geo]

Hi Geo, in which circuit and PCB of PULS STAR
your work?

Hi Georgi.
Thanks for your info about the construction of this detector.
I used the pcbs who are at post No282 and the schematic that you edit to Mesyna.
Problem begins with pulse at IRF740. It is 350V not 600... 700v that you write.
I will replace the coil and i will inform you.

Regards

[georgi.g.zhelev]

Hi.
I connected it and it worked....
But not very good depth. Maybe on afternoon to try to adjust it and to connect a better coil, so to see what about this detector.
The discrimination works but not so good. One piece of pcb is detected as non-ferrous but a coper coin is detected as ferrous.
I will tell more later after the adjusting...

Regards

Hi Geo, in which circuit and PCB of PULS STAR
your work?

[Geo]

Hi.
I connected it and it worked....
But not very good depth. Maybe on afternoon to try to adjust it and to connect a better coil, so to see what about this detector.
The discrimination works but not so good. One piece of pcb is detected as non-ferrous but a coper coin is detected as ferrous.
I will tell more later after the adjusting...

Regards

[Geo]

Hi.
I test the Tx part...
I connected a 280uH coil to the pcb and i gave it 10.6V and 14V from the Lab power supply.
At 14V the current was 100ma. I increased the voltage to Mosfet from 14 to 25V. The current consumption went to 190ma. I put a small Al-cool to the fet and i let it to work for half hour without any problem or high temperature. The frequency was 120Hz and the pulse width 400us!!!!!!!.
Very good stage.

Regards

[Geo]

Hi.
This photo is from here not from Thunting....

http://geotech1.com/forums/showthread.php?t=10894&page=5