MiniPuls3 Problems

[johnyp]

Oh my god you are right. I will study again opamps and come back to talk again. Thank you.

[johnyp]

I found that 5 volts TVS diode is the 1N6373. Does anyone knows how to tell if the diode that i will buy will be uni or bidirectional and how about the polarity ? If it is bidirectional it should not have the anode line right ?

[Qiaozhi]

I found that 5 volts TVS diode is the 1N6373. Does anyone knows how to tell if the diode that i will buy will be uni or bidirectional and how about the polarity ? If it is bidirectional it should not have the anode line right ?

A bidirectional diode is known as a "diac". If you are buying a diode, it will be unidirectional.
Also, the line marks the cathode, not the anode.

[porkluvr]

Hi all,

see this link for D4 replacement (producer is FUNAI):
http://elektrotanya.com/files/forum/.../Supressor.pdf

or:
http://elektrotanya.com/?q=hu/conten...-helyettesites

(first comment, supressor.pdf)

brg

Rumcajs

Your post did not go unnoticed and thank you for your input.
Fortunately for me, I could just as easily obtain an On Semiconductor manufactured component if I needed to, but your information might come in handy for somebody in some other part of the world.

[porkluvr]

I found that 5 volts TVS diode is the 1N6373. Does anyone knows how to tell if the diode that i will buy will be uni or bidirectional and how about the polarity ? If it is bidirectional it should not have the anode line right ?

You can sometimes plug the part number into your favorite search engine (such as Google.com) and get useful links to manufacturers datasheets.

Or, here is a link that I find very useful for researching component data:
http://www.datasheetcatalog.com/

Confucius say:
Give somebody a fish, and you feed them for a day. Teach somebody how to fish, and you feed them, er, until their tackle gets ruined or they lose all the fish hooks.

[Alexismex]

Thanks for the link porkluvr

[Alexismex]

This also interesting :
http://www.findchips.com/

[johnyp]

Yes i did found the datasheet but the diode comes in both versions and didn't know how to tell which is what. Now i do. Thank you very much.

[NormanB]

hi,

[johnyp]

Hi Norman. Nice to see you here too.

[NormanB]

Hi johnyp,

have you got any news about your mp3-project?

best regards

norman

[Tepco]

Hello. Some days ago i built the minipuls3 project from pulsdetector.de website and have one problem. The detector works fine except that detection depth is really low. It can detect a metal jar at max 10cm depth. The only think in the design i did not manage to find and did not solder is the 5.0 Volts surpressor diode D4. Is it possible the absence of this diode to give me those problems ? If anyone have built this detector please tell me your experiences. Thank you and sorry for my bad english.

What type of device you use for Q1 ? Did you managed to obtain original MTP2P50E? If you did, forget it as soon as possible, and use IRF9640 instead. Suppressors are not critical, use two regular 4V7-5V1 zeners, series connected back to back. This detector derives it's timing reference from coil signal directly, (via Q2), and 4148 or something will not work here

[johnyp]

I did use IRF9640 and i did not put anything in place of the 5 volts supressor. My mp3 worked when i constructed a proper coil only that i think it is not so sensitive. Have you made it also ? Thank you

[Tepco]

I didn't build MP3, but i did lot of other detectors. There are few problems whit MP3.First, power device (MTPxxx) is completely unsuitable for PI machines, appears like schematics is intentionally sabotaged, but this is not a main reason of your problem.

In this detector, timing sequence is initiated by RB0 signal from Q2 collector.Install 2 zeners, and if you have scope available, check this waveform, but most probably this is not an issue (detector works, so you didn't blew up anything, this will probably work without any suppressor or zener).

Most probable issue is the value of damping resistor R1, too high value for any reasonable coil. This will produce ringing, and multiple false "trigger" signals from Q2, MCU will be confused and will mess up whole thing in software.

What you need to try is lowering R1 value to, say, 330R or 390R, and try again. Original 2K is way too large, use just ordinary 1\4 or 1\2W resistor. D3 suppressor is not needed. If you now can obtain better sensitivity, optimize and adjust R1 value using the scope, for minimal delay without ringing at pin6 U3.This may depend on actual coil construction, and do this final adjustment when everything is completed, shield, cable etc.

This is the most probable source of your problem, underdamped coil.

I would like to hear any feedback, and information on detector performance, it is worth to build it etc, good luck whit this project.

(And sorry for my language too...)

[johnyp]

The truth is that now works quite well. On air i get about 1 meter for an object in size of a beer can. Anyway now i want to built one with discrimination and with 2x16 lcd and only an autotune button without any other controls. I found the tracker-pi2. Does it worth the time ? Thank you.