Gaussmeter Kit Group-Buy

[David Schwab]

Newark Electronics has 78 of the AD22151YRZ in stock.

US - Electronic Components Distributor | Newark.com

Thanks. My order at Allied is "Non Cancelable Non Returnable", so I'll just have to wait it out...

[StarryNight]

sadly, I was able to calibrate the unit but "out of range" is the only thing that is displayed once it boots up. I've got the cap at the sensor. I'm pretty sure the three wires are where they should be. To be honest I wired them incorrectly the first time. It did give me odd readings of 12,11...etc but was not affected by any magnetic field. Any suggestions to troubleshoot the problem?

[StarryNight]

update: I removed the cap at the sensor and it seemed to be reading as it should but after 5 min or so now it's giving me numbers randomly then it says out of range briefly and then goes back to random numbers, (without any magnets nearby). I've tried to use the reset but no luck

also the hall sensor feels quite warm to the touch.

in reading farther back on this thread I think I might still havethe sensor wired incorrectly. I will look again tomorrow.

[-Elepro-]

To be honest I wired them incorrectly the first time.

- sensor A1302 don't has any polarity inversion protection then when you solder it check well the pinout....

probably your sensor is dead.......

[RedHouse]

Yep, the warmth and the "out of Range" message are the signs that the sensor is F.U.B.A.R. in retrospect we probably should have budgeted for extra sensors, you are the 4th to report having this problem, David was the first to post publicly about it here post 375.

Here are some links so you can get another sensor:

Digikey: A1302

Jameco: A1302

Newark: A1302

Just to reiterate for the next guy, this is the pinout/hookup diagram for the Allegro A1302 sensor:



and another diagram is also found on page-7 of my GaussMeter_v2.pdf:



The A1302 sensor wiring is turning out to be the bump in the road on this DIY project. I really thought it was going to be the PIC installation that would be the snag.

[Joe Gwinn]

How to tell a bad sensor from a bad circuit

If one temporarily replaces the Allegro with a linear potentiometer whose slider is connected to the sensor-output input of the circuit board, the other two pot terminals being connected to Vcc and Gnd, with the pot set to 50%, one should get a nominal zero-gauss reading, and the reading will vary as one turns the pot this way and that. The pot resistance isn't that critical, and 10K ohms should work.

I've built all but the sensor cable assembly, so I will soon try the potentiometer test.

And will be careful not to install the sensor backwards, which seems to be the root cause of the feared warm-but-dead-sensor syndrome.

[RedHouse]

If one temporarily replaces the Allegro with a linear potentiometer whose slider is connected to the sensor-output input of the circuit board, the other two pot terminals being connected to Vcc and Gnd, with the pot set to 50%, one should get a nominal zero-gauss reading, and the reading will vary as one turns the pot this way and that. The pot resistance isn't that critical, and 10K ohms should work.

I've built all but the sensor cable assembly, so I will soon try the potentiometer test.

And will be careful not to install the sensor backwards, which seems to be the root cause of the feared warm-but-dead-sensor syndrome.

Easy Joe, I'd leave that for the experienced folks only, inexperienced experimentation with the input line to the PIC might ruin the PIC also. It's cheaper to get another A1302 that another PIC from Italy.

I recommend members build their probe (w/o the PIC installed) then install the PIC and test the unit.
(static strap on of course)

Try not to touch or otherwise play with the sensor wiring (PIC input) as little as possible.

[defaced]

Let's see if I don't do a good job of demonstrating my ignorance - this is all off the cuff. If I recall right, the sensor puts out a voltage which the PIC reads via an ADC and calculates a number. To verify the operation of the sensor, couldn't one build the circuit less the PIC, power it up, and use a volt meter to read the DC voltage out of the sensor with respect to GND?

The other question, and I haven't looked in the data sheet of the sensor to see if this would work, but would it be safer to just install the sensor and run just it from a the 1.5v of an AA(A) battery to and read it's output voltage? The idea being to give it just enough power to work but not enough to fry if it's installed incorrectly.

[realtonecustompickup]

Where to find the value of the Gauss pickuks different?

thank you

[StarryNight]

ok, well all things considered I guess it could be worse. I'm going to order both the A1302 and the AD22151YRZ while I'm at it. Can anyone point me to the right A1302 in this list? http://www.newark.com/jsp/search/bro...Ntt=A1302&Ntx= I think it's the A1302EUA but I'm not sure.

I was also thinking about getting the mounting jacks for conn4 as I'm concerned about soldering those three holes anymore than I have to. Are there part numbers for those little guys?

[David Schwab]

I think I'm going to wire up the sensor to a stereo 1/4" phone plug and jack setup. I can make a short probe on the end of a 1/4" phone plug, and it's a nice sturdy connector. I have plenty of room in the case for a stereo jack.

Then I can easily swap probes, and store their calibration in the two probe presets.

[David King]

I think I'm going to wire up the sensor to a stereo 1/4" phone plug and jack setup. I can make a short probe on the end of a 1/4" phone plug, and it's a nice sturdy connector. I have plenty of room in the case for a stereo jack.

Then I can easily swap probes, and store their calibration in the two probe presets.

David, as much as I like this idea I'd be a bit concerned about someone changing probes with the power on and frying the sensor.

From what I can tell the sensor is most sensitive to getting the (+) supply voltage to the wrong pin, specifically to the sensor output.
If you go ahead with this plan I'd put the (+)Vs to the Tip and not the ring or ground lug. That way the Vs is the last connection made as the plug is inserted and Vs won't rake across the output and ground terminals on the way in.

If you have the room then a mini DIN or even an XLR jack would be safer. I'd personally want to use a small Deans polarized 3 pin plug from an RC model shop (used to connect servos) as these are so cheap and widely available.

My sensor has come back from the dead but it didn't get Vs to the wrong pin I'd only flipped the ground and the output connections.
I discovered that some of my out-of-range readings were because the heat-shrink tubing I installed over the sensor leads had caused an intermittent short. Be sure to check for this possibility before tossing the hat in.

[David King]

Where to find the value of the Gauss pickuks different?

thank you

Your Automatic translation might be interfering with your meaning here.

Are you asking where to take the measurements?

We'd mostly be using these to determine the relative strengths of alnico magnets. I have been taking measurements at the ends of the poles but I get very different readings depending where the sensor is on the pole end, one section on the rim will often be 10-20% higher or lower than another section.

Ideally we want the bigger picture or an average reading. I suppose one could make an array of sensors and sum all the readings to get a single accurate number but that's probably overkill.

For other types of pickups you can take a series of readings and make a little map but I don't really know how you will use this data so you need to be more specific about what you want to do.

[realtonecustompickup]

Your Automatic translation might be interfering with your meaning here.

Are you asking where to take the measurements?

We'd mostly be using these to determine the relative strengths of alnico magnets. I have been taking measurements at the ends of the poles but I get very different readings depending where the sensor is on the pole end, one section on the rim will often be 10-20% higher or lower than another section.

Ideally we want the bigger picture or an average reading. I suppose one could make an array of sensors and sum all the readings to get a single accurate number but that's probably overkill.

For other types of pickups you can take a series of readings and make a little map but I don't really know how you will use this data so you need to be more specific about what you want to do.

I'm sorry I'm not good at English.

I mean, Where to find information gauss rate ?
how values Gauss affect sound ?


thank you very much , David king

[peskywinnets]

Redhouse...in your picture showing the probe (09-09-2009 03:12 PM) ...it's difficult to see, but is the Allegro bent at 90 degrees (on account that your follow up post shows the Allegros' activ area is on the 'flat'.

Also, can anyone point me to a place where I can source a trannie socket suitable for plugging the allegro into? (for easy sensor changing)