timb
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Re: Motor driver not working! :(

Thu Apr 04, 2013 11:57 pm

Okay, awesome! I found the buck regulator at Digikey for a dollar and some change. Now, the inductor needs to have a saturation current greater than 3A, but what about the current rating itself. Am I shooting for 2A there? And what sort of packaging am I looking for for the inductor?

Hmm, oh, what type of connector was originally intended to go at J9?

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Gert van Loo
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Re: Motor driver not working! :(

Fri Apr 05, 2013 12:17 pm

I will see if I can make a parts list this weekend but I am rather 200% loaded at the moment :-(

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Gert van Loo
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Re: Motor driver not working! :(

Sat Apr 06, 2013 4:11 pm

>>but what about the current rating itself. Am I shooting for 2A there?
Yes.

>>And what sort of packaging am I looking for for the inductor?
The PCB has a 10x12 mm footprint with two big solder areas. So anything that drops on there will be OK

>>Hmm, oh, what type of connector was originally intended to go at J9?
Three contact barrel power jack male. See picture below.
Choose the pin thickness which fits your power supply.
Attachments
MFG_PJ-058BH_small.jpg
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silverfox0786
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Re: Motor driver not working! :(

Sat Apr 13, 2013 11:43 am

Gert van Loo wrote:I will see if I can make a parts list this weekend but I am rather 200% loaded at the moment :-(

when you do get a chance to make a part list

can you include one for the Version 1 with the switched regulator part, for people that don't mind paying for the expensive part

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silverfox0786
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Re: Motor driver not working! :(

Sat Apr 13, 2013 1:31 pm

Gert van Loo wrote:No that is the linear regulator one which gets waaay to hot.
It can still be used if you replace the standard linear 7805 with a switch mode version, but they are rather expensive:
Like these http://www.murata-ps.com/data/meters/dms-78xxsr.pdf
There are others (cheaper) an somebody once mentioned it in a post, but I can't remember where.



This is the new one on the assembled Gertboard

would this work

http://www.pololu.com/catalog/product/2107

or this

http://www.digikey.co.uk/product-detail ... ND/1926159

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Gert van Loo
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Re: Motor driver not working! :(

Sat Apr 13, 2013 8:38 pm

No, not enough current. You need 700mA for the Pi and a ~100ma bit for the Gertboard.

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silverfox0786
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Re: Motor driver not working! :(

Sat Apr 13, 2013 11:13 pm

basically at least 1A (800mA minimum)

gregsmith_to
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Re: Motor driver not working! :(

Sat Apr 27, 2013 9:21 pm

Is this a suitable inductor? it appears to be ok electrically but a bit large for the site (12 mm x 12mm ) http://canada.newark.com/wurth-elektron ... dp/08P2777 I can't find a 10mm one which is good for 3A...

jjalert
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Re: Motor driver not working! :(

Wed Jun 17, 2015 6:39 pm

I know this thread is over 2 years old, but has anyone built out the power circuity?

How does this work for an inductor? http://www.digikey.com/product-detail/e ... ND/2626118

Only 2.5A current saturation, but handles 2.2A current, and fits in the 10mm x 10mm pad on my circa Oct 2012 gertboard.

jjalert
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Re: Motor driver not working! :(

Sun Jun 28, 2015 12:01 am

Update: I built this out and it works great to power the Gertboard and my rpi model B.

Attached are the parts I used. I replaced the Gertboard 3002 ADC with a 3202 while I was at it, hence the reason it's on the list, but that's certainly optional. I'm not sure if it's the new power circuitry or the ADC upgrade since I did them both at the same time, but there is a lot less noise in my analog measurements now.

Make sure to select the proper part quantities based on the circuit design, plus any extras you might need in case your soldering skills aren't up to the task. An extra fine point soldering iron tip would come in handy as well. The tip of my 100w soldering station is about the size of one of those golf pencils, and that made things a bit more challenging. :)
digikey.jpg
Digikey part numbers for Gertboard power circuitry.
digikey.jpg (38.77 KiB) Viewed 7797 times

JamesPi123
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Re: Motor driver not working! :(

Sun Nov 06, 2016 8:00 pm

Gert van Loo wrote:No that is the linear regulator one which gets waaay to hot.
It can still be used if you replace the standard linear 7805 with a switch mode version, but they are rather expensive:
Like these http://www.murata-ps.com/data/meters/dms-78xxsr.pdf
There are others (cheaper) an somebody once mentioned it in a post, but I can't remember where.



This is the new one on the assembled Gertboard
Do add a power supply or not, can you use a battery?

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