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Grogster

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Posted: 05:43pm 21 Nov 2014

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Thank you for your words of kindness.

Actually, thanks to several other members who have also made similar comments.
I do believe in and like constructive criticism though - that's why I put up the design(s) at all - so people can critique them, and in the process, perhaps see a better way of doing things.

But as you and others have said - lets get the damn things made!

I will submit the order tonight. I will probably get them through Shenzhen2u.

Smoke makes things work. When the smoke gets out, it stops!

WhiteWizzard
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Posted: 09:58pm 21 Nov 2014

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The MOSFET protection is something I have always used whenever I use LiPos in a 'portable' piece of equipment. The only time I have seen it used in a magazine was recently in SC in a project that was in one of the early editions that Geoff's MicroMite series ran (I think June's edition (maybe a month either side).
The project was a voice recorder with TFT (and LiPo).
Check out the circuit diagram around the -ve side of the LiPo; also read the circuit description for the theory of operation . . . .

As previously said - it works well, and is cheap, so is worth adopting for those of you still using a diode for reverse polarity protection.

centrex

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Posted: 05:28pm 22 Nov 2014

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Hi Grogster
Are you likely to put the gerbers on the forum?
regards
cliff

Cliff

robert.rozee
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Posted: 01:31am 23 Nov 2014

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i presume the mosfet protection being talked about is similar to the following:
http://www.ozqrp.com/rev_pol.html

expanding on this, with a couple of P-channel mosfets arranged back-to-back (plus a few smaller parts) you can achieve both reverse polarity and over-voltage lockout, with both mosfets sitting nicely in the highside. a company i used to work for 10 years back had a standard circuit for this that was implemented in most of their products. you could hook up 230v mains to an (intended for) automotive system and have no damage.

but then another company took the simpler approach, as at the start of the above linked page: a fuse and a crowbar diode. the slightly more refined approach of a polyfuse and crowbar diode makes sense for something using a micromite.

rob :-)

paceman
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Posted: 03:02am 23 Nov 2014

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WhiteWizzard said The MOSFET protection is something I have always used whenever I use LiPos in a 'portable' piece of equipment. The only time I have seen it used in a magazine was recently in SC in a project that was in one of the early editions that Geoff's MicroMite series ran (I think June's edition (maybe a month either side).
The project was a voice recorder with TFT (and LiPo).

The Silicon Chip article mentioned above is in the June issue page 42; "Touch Screen Digital Audio Recorder Pt.1". There is another example in the Nov 2014 issue page 82; "One Chip Mini 2x5W Stereo Amplifier".

Greg

Grogster

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Posted: 03:40am 24 Nov 2014

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PCB's ordered. I have received confirmation from Shenzhen that the boards are pending, so they must be happy with the layout. I will let this thread know when the boards arrive.

Smoke makes things work. When the smoke gets out, it stops!

Grogster

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Posted: 03:34am 02 Dec 2014

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UPDATE: Just got emailed the photos of the finished boards.

Shenzhen seem pretty efficient with the whole process. I also like their prices, and the photos they send of the boards before they ship them to you - a nice touch.

EDIT: Looking closely at the photos, it would seem that the silkscreen registration is slightly to the left of where it should be, but I guess that does not really matter - the copper etch looks fine. The boards are so cheap, I suppose something has to give!

Edited by Grogster 2014-12-03

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Grogster

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Posted: 07:52pm 08 Dec 2014

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PCB's have arrived.

Those who PM'ed me for a board - I will be in touch shortly, but for anyone else who wants one, flick me a PM.

Smoke makes things work. When the smoke gets out, it stops!

bigmik

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Joined: 20/06/2011
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Posted: 08:00pm 08 Dec 2014

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Grogster said PCB's have arrived.

Fantastic,

How do they look?

Is the registration error on all of the PCBs?

Mick

PS. Your lot went in the post a couple days ago.

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

Grogster

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Posted: 08:18pm 08 Dec 2014

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Hi Mick.

Silkscreen registration is out a little. My 1st board(Expandamite - the SS one) was fine.

Registration is out by about 1mm across the board, on all boards.

I don't REALLY care that much - I am just being picky.

Smoke makes things work. When the smoke gets out, it stops!

bigmik

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Posted: 09:33pm 08 Dec 2014

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Hmm,,

None of mine show any registration problem, I agree it isnt a huge problem but 1mm is quite a lot.

Load your gerbers into this Online Gerber Viewer to see if it is actually your artwork

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

Grogster

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Posted: 10:05pm 08 Dec 2014

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Checked with Online Viewer, registration is perfect in the gerbers, but it is out on the actual board.

Note how the outline for the headers is off to the left, and also slighly lower then it should be.

Oh well.

Faeces occurs.

EDIT: Here is a link to a big image. You can't really see the issue with the photo above, as the forum software is squeezing the photo. If you follow the link, you will get a nice big image, and you can clearly see how the registration is off.

No biggie though. Etch is fine, soldermask is fine. The silkscreen is more cosmetic then functional.

Edited by Grogster 2014-12-10

Smoke makes things work. When the smoke gets out, it stops!

bigmik

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Posted: 10:08pm 08 Dec 2014

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Grogster said Faeces occurs.

I read that book, it was by Hoo Flung Dung

Oh well, I think something must have gone astray there.. It is no biggie any way..

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

Grogster

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Posted: 01:10pm 01 Jan 2015

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As Geoff has assembled his VideoMite PCB, and I have sent off a few to other members here, I thought I should assemble one myself, as I designed the bloody thing!

This shot is of it talking to one of those $6 MP3 player modules from eBay.

These MP3 modules are really impressive for the price and size, and sound great.
The only thing they lack, is a BUSY line. The chip itself does have a BUSY pin, but the module designers have not routed that out to a user pin for some reason.

If I am VERY careful, I might be able to solder a hair-thin wire to pin 10 of the SSOP and bring it out for connection - then seal it with a blob of glue or something, to stop it breaking off. I do have a Goot rework station, so this may be a job for it.

Smoke makes things work. When the smoke gets out, it stops!

CircuitGizmos

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Posted: 01:22pm 01 Jan 2015

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Where did you find the data sheet for the MP3 module?

Micromites and Maximites! - Beginning Maximite

Grogster

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Posted: 01:40pm 01 Jan 2015

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I found it here.

There are several documents you can download. The manual is in English.

The datasheet for the actual chip used, is all in Chinese though.
I ran it through Google Translate, to get it in English, then printed it out.

It is "Engrish" to some extent, but is is much more readable then some translations.

Google Translate does not touch any of the graphics or charts, so you will still need the Chinese PDF handy for that, but luckily, the graphics use English labels, so they are easy to read.

Smoke makes things work. When the smoke gets out, it stops!

viscomjim
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Posted: 01:40pm 01 Jan 2015

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Hi CircuitGizmos,

Here is the link for the manuals.

CircuitGizmos

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Posted: 01:48pm 01 Jan 2015

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The links are not loading for me...

Micromites and Maximites! - Beginning Maximite

Grogster

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Posted: 02:40pm 01 Jan 2015

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Will email a ZIP to you...

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bigmik

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Posted: 04:07pm 01 Jan 2015

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Grogs can you post a zip here as I cant see them either.?

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

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