Gaussmeter Kit Group-Buy

[52 Bill]

Kit arrived yesterday and after a few hours of building I now have a working Gaussmeter!

RedHouse: Really great job on the kits, instructions and user manual! You really deserve a standing O from this crowd.

A couple of questions/observations, I find that the sensor placement for taking readings is very touchy. I would strongly suggest having it mounted to a lead so that it can be easily moved around the magnet to find the sweet spot. Having the peak reading mode makes it a lot easier to deal with this.

I just grabbed a J-Bass PU that I had handy and took some readings and found that the North poles read stronger than the South poles of each magnet. Is this normal?

Again Thanks to all who helped make this happen!

[JasonG]

Here is the data sheet for the display. It gives you the viewing area size (for when you make your enclosure), ect.
http://www.newhavendisplay.com/specs...-FSB-FBW-L.pdf

[-Elepro-]

ad22151 is only in SOIC package

Be aware that there are few more supporting parts for that sensor (see data sheet)

datasheet is not perfectly clear but i think it's possible to use ad22151 without resistor: (look pcb image... pin1 has pad only for better solidity)
pin4 at gnd,
pin8 at 5V ,
and pin5 and pin6 put togheter are the output.......

like for A1302 the 0,1uF capacitor is suggested if you have probe with long wire

if you want wait i will test this solution when come back from holiday.....

bye

[David Schwab]

if you want wait i will test this solution when come back from holiday.....

grazie!

[David King]

I got mine up and running this morning but had a little trouble getting the right connections to the sensor. Look carefully at that diagram!

[RedHouse]

...found that the North poles read stronger than the South poles of each magnet. Is this normal?...

Seems to be.

I got mine up and running this morning but had a little trouble getting the right connections to the sensor. Look carefully at that diagram!

DEFINATELY!

...the data sheet for the display. It gives you the viewing area size (for when you make your enclosure)...

You can use a 2-9/16 x 10/16 window, seems to be just about right.

... thought it was the wrong one because of the SOIC case....

Yep, I forgot to mention that.

[David King]

I just wanted to re-post the instructions again...
Building the Elepro Gaussmeter

I'm wanting to set the probe calibration but the instruction PDF http://classicamplification.net/Gaus...ssMeter_v2.pdf
isn't very explicit about how to do this. There was a number on my probe on the blue tape, is this the number I enter?

[RedHouse]

I just wanted to re-post the instructions again...
Building the Elepro Gaussmeter

I'm wanting to set the probe calibration but the instruction PDF http://classicamplification.net/Gaus...ssMeter_v2.pdf
isn't very explicit about how to do this. There was a number on my probe on the blue tape, is this the number I enter?

Yes the numbers I wrote on the blue tape on each sensor are the calibration numbers that get your sensor the closest to the readings we got on Jason's and Wolfe's professional meters.

Page-4 of the PDF file, I tried to describe the proceedure to calibrate the unit to the sensor, I must not have been successful so let me try again here....

When you power up the unit (turn on power switch) you then immediately press and hold both the two pushbutton switches .

Hold them down until the LCD screen reads "Calibration ...Probe1...Ok" as seen on the first picture on page-4 of the PDF file.

If you pressed button-1 now it would toggle between Probe1 and Probe2, that is how you get access to the Probe2 area to calibrate it.

Since we are only setting calibration on probe1 there is no need to press button1 at this time so just press button-2 which means "Ok" or accept Probe1.

The LCD will change to read "Calibration...1.300mV/G ", it is now that you use button-1 to raise the value, or button-2 to lower the value mV/G.

Note: it will actually read whatever was last entered-in before, if this was a real instruction manual it would have read like "Calibration...x.xxxmV/G"

You will now use buttons 1-2 until you have the number I printed on your blue tape (attached to your sensor) showing on the LCD display. Think of it like using the channel-up/down buttons (+/-) on your TV

Then you will release the buttons and wait a short time until the display changes to "Store Value? ....Y/N" you will press button-1 for yes or button-2 for no.

After you accept or decline to store the setting the unit will re-boot and be ready to make readings.

[John_H]

Thanks Everyone

Thanks Brad; I know this had to take up a lot of your time. It had to be an outstanding effort on your part for this all to go so smoothly.

Thanks Elepro; Without your excellent design work, and you being so kind to share it with us, none of this would have been possible.

Thanks to All in the group buy; It was very cool to be involved in this.

[RedHouse]

...I know this had to take up a lot of your time...

Way more than I though it would when I volunteered.

...It was very cool to be involved in this.

I feel the same way John, it was way cool that we all pulled together and got this done!

...Thanks to All in the group buy....

(in my best emmy awards show voice)...

I'd like to thank Elepro ...ciao... for doing all the hard work.

I'd like to thank Bruce Johnson for his fine contribution with the stand-off's, spacers, screws, and how he had 'em all baged-up really helped me out.

I'd like to thank Jason and Stephanie Lollar, and Wolfe McLeod for all their help with the meter comparison tasks and being the kind hosts that they are.

I'd like to thank my wife because she stood by me all the way through this and really doesn't care what a gauss meter is.

I'd like to thank Tanquarey & Schweps for their fine contribution along with Bogle and St Michelle and...and...and... thank the good lord too because every day is a bonus at this stage

.
.
.

[RedHouse]

ad22151 is only in SOIC package



datasheet is not perfectly clear but i think it's possible to use ad22151 without resistor: (look pcb image... pin1 has pad only for better solidity)
pin4 at gnd,
pin8 at 5V ,
and pin5 and pin6 put togheter are the output.......

like for A1302 the 0,1uF capacitor is suggested if you have probe with long wire

if you want wait i will test this solution when come back from holiday.....

bye

So are you saying the 3 drift compensation resistors are not necessary?

[RedHouse]

My gauss meter all boxed-up, this is a SerPac "S series" 321-I box:
(like this: SerPac at Allied Elec)



Had to cut out the inner battery box to make it fit though, you can see how the battery needs to be all the way over to the wall to make room for the gaussmeter assembly.

The inner box takes up nearly 1/3 the available room inside the box, I also had to clip off two of the built in board mounting lands that were in the way of the toggle switches.

This is what the inner battery box looked like before I removed it:



That should be a good season opener for the show-n-tell section of this group-buy adventure!

[-Elepro-]

So are you saying the 3 drift compensation resistors are not necessary?

only R1 is for drift compensation.... and datasheet says:

If the internal gain compensation is used, an external resistor is required

then i think if i don't use internal compensation external resistor is not required....

R2 and R3 are for gain selection.... but we need gain =1 (0.4mV/Gauss) then R3 must be 0 (pin5 and pin6 put togheter) and R2 doesn't need....

R4 is for offset... but for us it's ok Vcc/2 @ 0 gauss (without R4 resistor)

....but datasheet is not very clear then i will try (in the second half of september when i come back from holiday )

tanks at all
bye

[David Schwab]

Brad, that looks good! Similar case to what I'm getting, and I think I'll have to do similar shenanigans inside the box.

I got mine all put together, but left the display board and PIC in their protective bag/sleeve until I get the case, which will be in the next couple of days.

I'm also deciding on how I want to do the probe... Now I'm thinking of a removable one, kind of the like the Elepro version, but not as long.

Nice the about having a calibrated sensor, is I can then calibrate the other sensor using a known magnet.

By the way, your circuit board was very nice to work with, as were Bruce's hardware. Very professional.

[David King]

I keep getting "out of range" on alnico-5 magnets (in peak hold mode, usually around 1650g) is that normal? Most of my .188" x .850" magnets measure 1200 or so but when two are side by side, as in a Jazz bass PU the "out of range" pops up pretty frequently.

I also get it on ceramics but it's more like a random event. I'll go from 71 gauss directly to "out of range" as if there was no in between. This a repeatable event. I did re-calibrate for my sensor which was way up at 1482. Is anyone else have this problem yet?

I'm now interested in getting the higher range hall sensor if anyone else wants to join me.