Gaussmeter Kit Group-Buy

[David King]

Those look like regular diodes, not zeners.

[-Elepro-]

about esd protection and external zener read pag92 of datasheet.....

[LtKojak]

Last but not least...

... today the kit arrived!

Thanks to the Italian Post Office today I'm officially the one who got it DEAD LAST! Do I get a trophy?

I'd like to thank Brad and all others that contributed to make this Kit-Group Buy possible.

Time to warm the solder iron up...

[spy]

[RedHouse]

about esd protection and external zener read pag92 of datasheet.....

Just as Joe described.

Those look like regular diodes, not zeners.

I think you're right, after zooming in I see all the horizontal lines have a little tail.

[Joe Gwinn]

Anyway, check out page 45-48 of the PIC16F883 data sheet, shows back-to-back zeners protecting the I/O pins.

I think they are ordinary silicon diodes, not zeners, because the text makes no mention of zener action, which means that zener action is not intended (although all diodes can zener).

This is actually good news. A pair of external diodes, especially schottky diodes, should confer great protection, between their greater physical mass and the lower voltage drop of a schottky diode.

The pair of diodes conducts the overvoltage to either Vdd or Vcc rail. It can be useful to put a 15 volt zener diode across the +9 volt input terminals, to protect the filter capacitors and 7805 regulator et al.

[RedHouse]

I think they are ordinary silicon diodes, not zeners, because the text makes no mention of zener action, which means that zener action is not intended (although all diodes can zener).

This is actually good news. A pair of external diodes, especially schottky diodes, should confer great protection, between their greater physical mass and the lower voltage drop of a schottky diode.

The pair of diodes conducts the overvoltage to either Vdd or Vcc rail. It can be useful to put a 15 volt zener diode across the +9 volt input terminals, to protect the filter capacitors and 7805 regulator et al.

Do you recommend any particular Schottly?

[Joe Gwinn]

Do you recommend any particular Schottly?

It isn't that critical, but ON Semi's MBR160 looks suitable, although I have not used it myself. This device is characterized as a low-drop rectifier diode.

http://www.onsemi.com/pub_link/Collateral/MBR150-D.PDF

Selection Criteria:

Breakdown Voltage: All such diodes are more than adequate.

Junction Capacitance: Not important in this application, given the capacitance already there.

Ability to absorb a big pulse: It's a rectifier, not a tiny small-signal diode. Rectifiers lead a hard life.

Reverse Leakage: This is the key issue in the gaussmeter. Too much leakage will affect gauss readings. I chose the MBR160 mainly on this issue.

[mickmutante]

Finally i received my kit today..!!! I just ensemble and it works great..!!!
This weekend I'm going to build a wooden case for it....

I have a question.... does the capacitor probe tip goes in parallel with the black (ground) and red cable (V+)..??

Again thanks to every one that participates in the group.!

[RedHouse]

Finally i received my kit today..!!! I just ensemble and it works great..!!!
This weekend I'm going to build a wooden case for it....

I have a question.... does the capacitor probe tip goes in parallel with the black (ground) and red cable (V+)..??

Again thanks to every one that participates in the group.!

Yes Mick, cap goes across the power and ground leads on the probe.

This meter does work great, someday when I can get over to Italy I'm gonna buy Elepro a beer!.
(or whatever he's drinkin)

[LtKojak]

Yes Mick, cap goes across the power and ground leads on the probe.

This meter does work great, someday when I can get over to Italy I'm gonna buy Elepro a beer!.
(or whatever he's drinkin)

Hey! I'm in Italy too, you know...? A mere 1.698Km from Elepro... no big deal if you fly a helicopter...

[-Elepro-]

someday when I can get over to Italy I'm gonna buy Elepro a beer!.
(or whatever he's drinkin)

beerS .... perfect for me.... or I could come in Sammamish if you find BIRRA MESSINA there...

[David Schwab]

I'm not in Italy, but my mother's parent were from there, so I'll just have myself a beer for you guys!

This weeks beer is Hoegaarden.

[defaced]

This weeks beer is Hoegaarden.

Superb choice.

[StarryNight]

Next time I'm in Chieti visiting my family. I'm definately buying you guys una birra fresca.
cin cin