Aout problem getting shunt

[dcer10]

Hi,

I am working on my sequencer and have the Aout board built and ready to connect, but I can not source the shunt that goes on the underside of the board. Does anyone have a spare or know where to buy one? Im really stuck, tried from MaxIC but they didnt send it to me.

Thanks,

John

[THeff]

Hi John,

I just built mine this weekend and I used an LM336-2.5 that I had on hand and it seems to work very well.  It's a TO-92 package with three leads but you only use two of them, the adjust pin it not connected.

Tim

[THeff]

Hi John,

I did some more investigation about the MAX6007B and it is a 0.2 % tolerance part at 2.048 V.  The best tol. LM336-2.5 is 1% at 2.50 V with no adjustment.  I'm not sure if it can be adjusted down to 2.048 V.  With the 2.5 V part installed I get 1.000 V and about 4.010 V out when I run the MIDIbox CV calibration program.  I was thinking that the MAX part was 2.48 V and not 2.048 V.  The LM336 may not be such a great choice after all.

Tim

[moxi]

to get the shunt, simply ask MAXIM for a free sample...

[MTE]

to get the shunt, simply ask MAXIM for a free sample...

thats right...i got one last week as sample

Regards

MTE

[dcer10]

Hi All,

I still cant get a shunt, I have requested samples from maxic 3 times now, other samples arrive but the shunt does not. Does anyone have a spare one?

Thanks,

John

[Altitude]

you sure your asking for the correct pn? I got mine in the mail today

[c0nsumer]

I still cant get a shunt, I have requested samples from maxic 3 times now, other samples arrive but the shunt does not. Does anyone have a spare one?

Why don't you just buy one from a supplier? Samples are generally intended for people who will use more in the future. If a bunch of people request samples and then don't follow through with orders, suppliers will tighten up their sampling, hurting students and those developing open source projects.

-Steve

[moxi]

Hi Dcer,

other samples arrive but the shunt does not

it happen that maxim send first one part of your sample order, then, one week after , the second parts...be patient...

[moxi]

Hi Dcer,

other samples arrive but the shunt does not

it happen that maxim send first one part of your sample order, then, one week after , the second parts...be patient...

[dcer10]

I did finally get some from a kind midibox user {moxi}, and then they arrive from maxic too! They too a very long time to get here, months but pics came quite quickly. Also cOnsumer, I would love to buy the parts from a supplier but I have tried all the electronics stores in Adelaide but none can get it and Ive had no luck buying them online. It would be nice if mike or smash took up a supply of the 525's and shunts to sell an Aout  kit at their shops.

[moebius]

It would be nice if mike or smash took up a supply of the 525's and shunts to sell an Aout  kit at their shops.

<bitchin' on>

Hmm.. I hope I'm not stepping on anyones feets here or getting another ban. ;D

<bitchin' off>

<sarcasm on>

But dcer10 - Why don't You start supplying MAX525s and the reference chips?

</sarcasm off>

The information I'm representing here might have came from the private conversations and not intended for the public, but I'll take that risk.

There was a time, when SmashTV's midibox shop didn't have LCD displays available, but those were requested from Smash regularly. Because those who ordered wanted a complete solution from the one place.

After a few lengthy discussions with him, he decided that it's worth the risk to bulk order displays - more or less to keep customers happy.

Anyone of You can just GUESS how the business model for a "midibox shop" (Mikes or SmashTVs) is build. "Keep the customers happy and You'll get a dime from a dollar".

LCDs were a risk investment for Smash, a few or more were broken and his pricing really doesn't even give back the time (= money) spent in the effort of testing every individual display ect.

---

This leads to the original request. What does (in the MAX525 page) $11.95 @ 1k mean - You'll have to invest to the stock (equals money), just sitting in Your drawer and wait for orders. There's nobody in the Midibox community who could take that risk.

Moebius

[TK.]

You could organize a "group buy" for special parts in order to get better prices...

Best Regards, Thorsten.

[dcer10]

Hi Moebius,

"But dcer10 - Why don't You start supplying MAX525s and the reference chips?"

If I was an electronics store I probably would. But im not, im a hobbyist. I have no idea of the minimum orders, or the economics of either of the stores, nor the risks taken, and as a consumer I dont need to know these things or debate them. I appreciate the presence of both shops and wouldnt want them to take a bad risk leaving everyone with nowhere to buy the kits. All I know is I would like to buy these chips rather than order free samples so I dont feel like a scab and there is nowhere I know of to do that :}

Maybe someone could look at doing a 1000 part order after seeing what other communities use the chips and trying to sell 1/2 off to them? These chips must be used in other similar projects??? I know for one I could not afford to do the order. If anyone was ever interested in a group buy as suggested by TK count me in!

All the best,

John

[moebius]

Hi Moebius,

Hi there!

If I was an electronics store I probably would. But im not, im a hobbyist. I have no idea of the minimum orders, or the economics of either of the stores, nor the risks taken, and as a consumer I dont need to know these things or debate them.

Neither of the Midibox stores are "general electronics" stores. As a DIYer (or as consumer) You should realize doing business for such a small community with low profits needs some planning, right? Doing 100 core kits is no problem, those will be sold. But buying say, 50 MAX525 is a risk investment. It's about the demand.

Maxims price breaks start at 25 pieces and it's still expensive (this is for RoHS compliant MAX525BCPP+, $21.99)

So, start up a group buy effort in the "fleamarket" and lets see how many people are interested.

Moebius/ Samppa

[Otterfan]

Back to the issue of repalacements for the shunt, has anyone tried the adjustable LM4051? I've done some back-of-the-envelope calculations to show that you could get a 2.047998 v reference with the right resistors. (If anyone's interested, it's R1=1.01M (1M + 10k) and R2=696.665k (680k + 15k + 1.5k +150 + 15). The high-end devices have a 0.1% output voltage tolerance, so with well matched resistors it should spec out at least as well as the MAX6007A.

They're less than $3 here in the States and Digikey stocks them.

I've ordered one and also a Motorola TL431 (an even cheaper programable reference, but with 0.4% tolerance). I'll test and post results once I get around to it.

[moebius]

The voltage reference isn't that important - as long as it's stable ;D

CV is anyway trimmed by Opamps after Max525s, I think.

Moebius

[Otterfan]

Cool. That National shunt looks plenty stable.  :)

[dcer10]

Moebius,

I think thats a great idea. I have started a new topic in the fleamarket to see how it goes.

http://www.midibox.org/forum/index.php?topic=7777.0

All the best,

John

[nebula]

MAX6007 doesn't seem to be in stock anywhere in North America, so the min is around 2500 pieces.  Digi-Key has MAX525 for around $38 each.  Since my sample requests have been unsuccessful so far, I'm going to buy two MAX525.

The LM4051 Adjustable seems perfect. The pinout is different, so it looks like you'd have to rotate it 1/3 turn clockwise and add a couple of resistors on pin 1, then it should work with no problem.  Otherwise it looks generally superior to MAX6007.  Did anybody actually try the National shunt?