Gaussmeter Kit Group-Buy

[RedHouse]

We'll use this thread for all our Gaussmeter Kit Group-Buy communications

The Who's-InList:
Redhouse
David Schwab
JasonG

Ok so that makes three (3), anyone else? we really need to get 5 or more to make it work at a decent price.
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Group Buy:
Having participated in a few group-buy's over on Prodigy-Pro and AX84 before and being familiar with the scenario is why I volunteered to coordinate this one here.

For those who have never participated in a Group-Buy, here's what typically goes down...

1.) Someone is designated to do the leg work, the group-buy coordinator, I have volunteered this time, it doesn't have to be me, someone else can do it.
2.) The costs and logistics are defined and agreed upon by the participants, in this public thread before any funds are transfered or parts are ordered.
3.) There is a "last call", then those who are in on the group-buy are given time to transfer their funds, when funds are tranferred to the the group-buy coordinator the group-buy is then publicly "closed" in this thread.
4.) When the thing the group-buy is buying is realised (in this case the "kits") they are shipped to the participants. Usually everyone lives happy ever after.
(or until the next group buy)

Some people who coordinate group buy's like to get extra stuff, I'm not that kind of guy so in this group buy there won't be any extra kits to be had later.

There can be another "Group Buy" later if there is enough interest but if you feel you might want one of these, you will need to step forward before the Group Buy is closed, there won't be any "extra" kits available.

There is an element of trust in a Group Buy, know that going in. I'm volunteering to do the coordination, the PCB's, the procurement and distribution ...but I'm not volunteering to carry everyone's finacing and collect later.

Finally, if one is unable or unwilling to pay their portion up front they really cannot participate in this group buy.
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Mod's: It would be good for the group-buy thread if this post could be updated after the fact, I'm not sure who the moderator here is, but if you (the mod) could either participate in this by doing the updates, or allow me to update this initial post as the group buy proceeds and is eventually closed that would make things go smoothly.
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Definition of THIS Group Buy:
We are putting together gaussmeter kits, this entails procurement of component parts, the pre-programed PIC (from member Elepro, in Italy) and the Display module, the manufacture of PCB's, the packaging and shipment to the participants.
***(no wire, solder, knobs, enclosure etc ...just the essential components in this kit)***

The participant understands that they are responsible for the final assembly, soldering of components, making probe leads and hookup wires, finding and installing into a suitable enclosure.

This a group-buy of the essential componemts of a DIY Gaussmeter Kit according to this parts list:
Gaussmeter project
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Parts:
I've been in contact off-line with Elepro, he want's 30-euro/each for the pre-programed PIC's which currently works out to around $43-USD. He has said if we get together an order of 5 or 10 he can cut us a price break.

I asked him if he would be interested in a license agreement to use his code, unfortunately for us, he's not. It's kind of a bummer we can't just buy the PIC16F883 from Mouser (at the current price of $2.28) load his software and throw him some cash, but he want's to sell pre-programmed chips only, shipped from Italy.

I'll work through Elepro's Mouser parts list in the next few days and get an estimate for parts costs. (I'm busy this 4th of July weekend)

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Boards:
I'm not interested in vero board layouts, I'll just make actual PCB's (myself) as I've lot's of experience in that area.
(see: ClassicAmplification.com)
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To Do...
JasonG brings up a good point, to make this fly properly we will first need to do a prototype to validate the unit and the PIC code by asking one of our members here to verify it against a known-good (calibrated) commercial unit. We would need to know if it's right-on, close enough, or not ready for prime time.


Any member who owns a decent commercial digital gaussmeter, who would agree to take part in this group effort, please PM me.

[spy]

I'm in for a complete kit!

[RedHouse]

Originally Posted by spy

I'm in for a complete kit!

Please read Definition of THIS Group Buy in the initial post, it's not a "complete kit" it is a kit of these components (Gaussmeter project) or whatever sub's are agreed upon , let me know if you are still in.

[spy]

Yes I have read it! Please count me in!

[Berman]

As calibration help you can use one or two magnets (one low, one high Gauss values) with high magnetic stability (perhaps neodym or ceramic), which are measured by an calibrated gaussmeter.
Perhaps one of your suppiers can help you.

Just an idea
Hermann (who not owns a gaussmeter)

[salvarsan]

Originally Posted by Berman

As calibration help you can use one or two magnets (one low, one high Gauss values) with high magnetic stability (perhaps neodym or ceramic), which are measured by an calibrated gaussmeter.

Bad news: The A1302 sensor has a worst case accuracy of 3%, (about +/-50 gauss), but they usually group within 1.5%. *Allegro stopped selling calibrated sensors a few years back.

Good news: A1302's measure reproducibly -- an old strat A5 pole that measures 1300G at 68F will always measure the same if you use the same sensor and use noise averaging calculations (Elepro does this very well).

If you don't need an ABSOLUTE gauss reading but will always use the same gaussmeter, the uncalibrated A1302 will work fine for guitar pickups.

-drh

[firewire]

I am in all the way! I was going over the list and the place I got stuck with was making the PCB. If that was premade it would have been no problem!
We get kits all setup and a good way to calibrate! Lets do it defenetly!!!
Count me in!!!!

[-Elepro-]

here's pcb eagle file....

i have made this design (with big trace, single face and with a wire jump too) so anyone can built it easily with a pcb pen.... but if you have professional builder you can change layout (to have for example connector on same side.... or for remove wire jump etc.)

important for pcb: I noticed that the trimmer in my pcb (with those dimensions and (important!!) possibility of bottom regulation is always available at my local store but it is not common.... check for availability so if it is not in stock we change pcb for another one...

bye

[automan]

Once you have a general estimate on the total cost, I will probably be in.I'd just like to have a ballpark price before I give my word to join.

[Bruce Johnson]

Do you have a rough estimate on the cost of the kit? If it's under $200, I'm in.

Absolute calibration isn't important to me. I'd use it for verifying production batches and "relative-to" experiments.

Also, if any custom electronics metalworking (brackets, heatsinks, housings, etc.) is needed, I could provide that for the group.

[spy]

Originally Posted by Bruce Johnson

Also, if any custom electronics metalworking (brackets, heatsinks, housings, etc.) is needed, I could provide that for the group.

This is great! If you can make an enclosure for the meter I'm in! If the other members agree we can add it to the groub buy!

[David Schwab]

Originally Posted by spy

This is great! If you can make an enclosure for the meter I'm in! If the other members agree we can add it to the groub buy!

You can get all manner of cool premade plastic enclosures this would fit in.

[spy]

Yes of course! There are a lot of cool plastic enclosures... just in case Bruce Johnson would offer one ready-to-use in an affordable price and cooler than a plastic one!

[RedHouse]

Originally Posted by spy

This is great! If you can make an enclosure for the meter I'm in! If the other members agree we can add it to the groub buy!

Well that's the second "If you do this...I'm in".

An enclosure can add additional cost ($10-$75) to the kit. My goal would be to keep the group-buy portion of this to a minumum cost to get the appropriate component aquired and distibuted, I think we might be getting hung-up on the work "kit" which seems to mean different things to differnt people.

We can have any additional offers by others post them here in this thread as BruceJ just did this way anyone who needs/prefers spending additional funds on additional parts/services can certainly do that as well, but still keep the component kit price to a minimum and not force other into buying uneeded items just to participate in this group-buy.

Spy, you get with Bruce and figure out if he can/will make you an enclosure, then let me know if you are in. I already have enclosures for my needs.


Salvarsan, it's not bad news really, IMHO a 3% tolerance is workable. I will be using the meter to make relative measurements mostly, both my own magnets and other makers magnets.

[Bruce Johnson]

Yes, my offer of building an enclosure or any other hardware doesn't have to be part of your group buy kit. Some of you may prefer to build your own. I can make up an enclosure that suits my purposes, and then offer copies of it to any of you who want it.

[RedHouse]

Originally Posted by Bruce Johnson

Yes, my offer of building an enclosure or any other hardware doesn't have to be part of your group buy kit. Some of you may prefer to build your own. I can make up an enclosure that suits my purposes, and then offer copies of it to any of you who want it.

Sounds good Bruce

[RedHouse]

Originally Posted by automan

...I will probably be in.I'd just like to have a ballpark price before I give my word to join....

As it should be automan.

I'll work through Elepro's Mouser parts list in the next few days and get an estimate for parts costs.

I'm busy this 4th of July weekend, but trying to stay tuned-into this thread as much as I can.
(when I'm near a computer, that is)

[spy]

Originally Posted by RedHouse

Spy, you get with Bruce and figure out if he can/will make you an enclosure, then let me know if you are in. I already have enclosures for my needs.

Brad, I'm in from the beginning!
No problem if there is an enclosure or not! Just thought that it'll be a great idea if the other members of the Group Buy would like an enclosure from Bruce. If they don't like it that doesn't change my decision. I'm in all the way!

[David Schwab]

Originally Posted by Bruce Johnson

Yes, my offer of building an enclosure or any other hardware doesn't have to be part of your group buy kit. Some of you may prefer to build your own. I can make up an enclosure that suits my purposes, and then offer copies of it to any of you who want it.

And Bruce, I certainly wasn't saying we shouldn't use a nice custom case you might come up with! Just that there are a lot of cases available from electronic parts distributors, and was directed to spy, so he would get into the buy!

[RedHouse]

GROUP VOTE NEEDED:

For those who are "in" on this group-buy, go here and post you preference of which display color you would prefer if we buy from Mouser:

NHD-0216K1Z-FS

{EDIT} I liked the "Gray" one at first glance, but after looking at them on the website link below I definately like the white-backlight one the best. Much easier to read, more like a cell phone backlight.

{EDIT} you can look here on their website to see the displays and do a mouse-over to see them w/o their backlight.
Note that not all displays on this webpage are the ones specified for this project only the NHD-0216K1Z-xxx will work for us, but it's cool weblink anyway, check it out!
2 x 16 Characters


BTW; I ordered some A1302 (hall sensor) from an eBay seller out of Korea last night, got them for under $2/ea.

PS: I should be able to finish working through the Mouser list tonight. I have found an offshore supplier on eBay that sells a display module which looks like the one Elepro used, just waiting for a data sheet response, so that is another option if we don't like the Mouser offerings.

[RedHouse]

Originally Posted by David Schwab

And Bruce, I certainly wasn't saying we shouldn't use a nice custom case you might come up with! Just that there are a lot of cases available from electronic parts distributors, and was directed to spy, so he would get into the buy!

Same here, I wasn't saying "no" to a case, I was just saying that as for me, I'd prefer to get my own outside of the group-buy.

I would think that Bruce would need an assembled component kit to develop the case layout, so waiting on a case would hold up the whole group-buy.

[spy]

Grey is cool! I vote for Grey.

Great with the A1302, and at a very low price!

[DrStrangelove]

Guys, A1302 sensors are hardly unobtainium.
I bought 25 of them from Digikey.com a few months ago for ~$1.20 each.

Elepro gives six suggestions for the LCD display, and spec'd them on a
Mouser project manager parts form for us at:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=2c947e7457

Don't be put off by the $75 total price -- he gives six choices as to LCD display.
If you choose only one LCD plus the miscellaneous parts, the total is around $27.

Elepro has done a lot of the research and setup for us.
We should take advantage of it.

-drh

[-Elepro-]

Originally Posted by DrStrangelove

Guys, A1302 sensors are hardly unobtainium.
I bought 25 of them from Digikey.com a few months ago for ~$1.20 each.

Elepro gives six suggestions for the LCD display, and spec'd them on a
Mouser project manager parts form for us at:
https://www.mouser.com/ProjectManage...sID=2c947e7457

Don't be put off by the $75 total price -- he gives six choices as to LCD display.
If you choose only one LCD plus the miscellaneous parts, the total is around $27.

Elepro has done a lot of the research and setup for us.
We should take advantage of it.

-drh

don't watch that list in your link.... watch this (post #19) it is more or less the same in your link but better(i don't remember why but i will check again... ) .... the lcds in Redhouse post are right (they are in my list).... don't forget to select "low power backlight"..... I think that it's better rewrite list here....

but..... how many are in the group??

....about MCU:
my offer is 22EURO/each for 10+ order or 20EURO/each for 15+ order (shipping to group-buy coordinator included)

[Bruce Johnson]

I'm still in; gray is fine for the LCD readout.

About the enclosure, yes, I'd rather have the parts kit in my hands before I make one. So, we don't want to hold up the parts kit group buy. I'll just build an enclosure for my own meter, post pictures, and if anyone else wants me to make one for them, they can contact me. It's not going to be anything fancy...but I usually use a metal box rather than a plastic one.

I'm sure most of us can drill holes in a box! I wasn't sure if it needs any special metal parts like brackets, blocks, sensor mounts, etc. That's where I can help any of you that don't have the machinery.

[defaced]

I'm casually in. Meaning, I have to do some research on sensors and the meter range to see if it will work for a possible electromagnet project I might be doing for work. Since I have no concept of how much a gauss is, or how much gauss one thing puts out compare to another, I need to do some leg work.

[Yves]

I've made the gaussmeter designed by Antonio, and it works great for me.Since I've already made it, don't count me in, but here are a few comments that may help.


1/ I've ordered both the LCD with blue backlight and hall sensor from this Ebay store:
Boutique eBay - MIND-TEK : Connector, Resistor, Display LED LCD

I got 2 sensors+LCD and shipping cost for 12.50$ and everything was at my door (in France) well packed within a week. It cost me less than going to my local store just to buy the LCD, not to mention the hall sensor which isn't that common to find. I can say that the LCD is compatible, no problem.

2/ Since this LCD requires backlight, I've replaced the switch at conn2 by a wire strap, and used this switch instead of the push button at conn6: I prefer to have a toggle switch to choose between the normal/peak hold modes

3/ Regarding the size of R1 and its access through the back of the board: I haven't found the matching part, so I have used another one (which I had to slightly bend the pin to fit in). Mine has access through the top, so I've use wires instead of connector to attach the LCD so that I can lift off the LCD to access R1, should it be needed (see pictures). BTW, I haven't used any connectors but soldered wires directly on the board.

4/ I've removed the decoupling cap attached to the sensor. I found it too bulky at the extremity of the probe and since there is no much reason to have massive spikes in there, I thought it would be OK. It works for me.

5/ Regarding the calibration. From my point of view this is a really usefull tool to compare gauss reading between different magnets and assemblies. However, I personnally don't see much point of having an absolute calibrated reading as long as this fall within decent tolerance and repeatabilty which I believe is the case. So I don't mind if this is not calibrated.


Hope this helps

[RedHouse]

Originally Posted by -Elepro-

...

but..... how many are in the group??

....about MCU:
my offer is 22EURO/each for 10+ order or 20EURO/each for 15+ order (shipping to group-buy coordinator included)

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The Who's In List: (July 6, 2009 7PM)

7 Definate Participants:
Redhouse
David Schwab
JasonG
spy
firewire
Bruce Johnson
Arndawg56

2 Possible Participants:
automan
defaced
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We need a few more to get the 22-euro/$30.66-USD price break, a savings of $12-USD
(which is down from 30-euro/$41.81-USD of individual ordering)
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[RedHouse]

Parts Issues and Suggestions:

Going through the parts lists and validating through Mouser I find a couple things need adjustment.

1.) the PIC is a 28 pin chip, the socket that was specified was a 14 pin
(M# 517-4814-3004-CP ...should be... M# 517-4828-3004-CP

2.) the trimmer specified M# 652-3318S-1-203 a 20K trimmer is obsolete, non-stocked at Mouser so I found the Phier 531-PT6KV-10K a good substutute and is available in the originally specified value of 10K, most importantly it IS adjustable from the back via the thru-hole in the PCB.

3.) the resistors specified are 5% tolerance carbon comp resistors, for only a penny more per resistor would the group mind if we changed-up to decent 1% Metal-Film resistors?

4.) Yes the A1302 are not unobtainuim and DrStrangelove mentioned Digikey has them at a current price of $1.37/ea, ...but... I ordered some from an eBay store ....soooo ....I need to know if it's gonna hurt anyone at $1.50/ea?

5.) The M#1055-TA2120-EVX ($2.20) toggle switch specified is "Mountain" brand, I've had bad experiences with Mountain brand switches in the past, they are really cheap-ass, like the mounting nuts are stamped and pressed sheet metal instead of a proper formed and tapped nut. Would the group mind if we changed-up to a decent C&K toggle M# 611-T101-001 ($4.05) I know it's twice as much but it's a much better switch...?

[RedHouse]

Originally Posted by Yves

...I've made the gaussmeter designed by Antonio, and it works great for me.Since I've already made it....

Wow! thanks for the validation Yves, appreciate you input very much.

[David Schwab]

I'm OK with the part upgrades.

[LtKojak]

As long as I can pay with a credit card, count me in as well.

I'm in Italy too, so Elepro, if you wanna contact me, you're welcome to do so.

Having an electronics background, I'm with RedHouse in buying better components for the project.

[mkat]

Count me in as a tentative participant, pending on re-reading -Elepro-'s thread.

[mkat]

Yep, ok, read it. I'm in. Please update the list.

[spy]

No problem with the upgrades....