Metal detector with meter discriminating

to SASHO-bg

Hello,
Thanks for fast replys!
Sasho can you tell me R42 is?k,m or?????

Polarized capacitators-16-25 volts.
No polarized capacitors-63-100volts.

[chemelec]

When I search for capacitators in shops and they ask me "in which voltage range???"what shell I answer???
please help me I am realy a noob!!!
Thanks

Any voltage rating that is Greater than the Battery Voltage shoud be OK.

Hi

Hi,have anyone finish this PCB?

When I search for capacitators in shops and they ask me "in which voltage range???"what shell I answer???
please help me I am realy a noob!!!
Thanks

Work also with КП303.Made in Rusia.

[porkluvr]

substitute pinout

Hold on - 2N4393 and J113 have the same pinout, and it is the TIS75 that must be turned 180 deg. Aggh. I'm sorry, but I lied.

Oracle I ain't. Dyslexic, oot. Always be safe and consult the appropriate manufacturer's spec sheet for any device before applying overvoltage.

[porkluvr]

porkluvr,
what is your opinion about 2N7000 (2N7002)? I see these used on motherboards.

Kt315:
The 2N7002 is enhancement mode MOSFET. So, I thought it appropriate, and a simple matter to test with pull-up to positive rail instead of pull-up to ground.

I hooked up LTspice to test the idea. I did not "wire" the exact same circuit, just a quick and dirty test with a 200mvP-P 50kHz sine wave getting switched through; something for easy to eyeball results. Tested side-by side with TIS75 and 2N4393 (remember these are only models, and not the real thing).

I was disapppointed. I tried several different pull-up biasing schemes; different voltages (including ground), and different pull-up resistor, but the 2N4393 and TIS75 performed (their circuits remained unchanged) while the 2N7002 did not perform well at all, no matter what I tried. Of course, I did not try everything, and maybe I'll try again later, but enough is enough. I know when I've been beaten. We have something that works, so there is no need to fit a square peg into round hole (not today)!
Dang it, I've got a bucket load of these in the SOT23 package that I hope are good for something besides driving LEDs and buzzers. If I come up with a better use for them I'll let you know!
Consider that 2N7002 is more of a power device, whereas 2N4393 is for small signal. I can't explain any better than that, it's all I know.

[Qiaozhi]

What leads you on that I can use 50-0-50 ma meter?
Because I wanna this project to be as close as I can reach!

Hmmm... I don't think I said a 50-0-50 mA meter is ok. I said that it looks like it needs a 50-0-50 uA.
Anyway, I see that Sasho has already replied.

[kt315]

porkluvr,
what is your opinion about 2N7000 (2N7002)? I see these used on motherboards.

[porkluvr]

2N4393 substitute

Hello Geto
One of the main features of 2N4393 FET is low cut-off voltage. I have read other people suggest that a European equivalent is a BF245c, although from looking at the spec sheet, I can't see why BF245A is not a better choice from that group. Maybe somebody can clarify that.


TIS75 should also work. I think also J113 should be OK, but it has exactly reversed pinout. Just turn J113 around 180 degrees.

Hmmm, does anybody wanna thwack me for my choice of BF245A (or any of the others)? I could be a bonehead.

[Geto]

Hello,

Thanks!
What is this pn4393?
Can I use some equal substitue?Any Ideas?

METER IS -50-0+50 MIKROAMPERS!!!

[Geto]

To Qiaozhi

What leads you on that I can use 50-0-50 ma meter?
Because I wanna this project to be as close as I can reach!

[Geto]

To Qiaozhi

Hello,
Thanks for help man!
I will ask For your help again I am shore for that.But I have to make this PCB!
In which Country you are located?