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:
http://music-electronics-forum.com/t13187/#post104680
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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]

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 (http://music-electronics-forum.com/t13187/#post104680) 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]

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]

Group buy

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]

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]

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]

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.