I provided electronic controls for my daughter's art project a while back - 
it had 100 solenoids, powered at 5 volts.  If all energized at once, it 
required 80A of current.  I used a supply from Jameco.  Part #196795
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=196795

It costs $12.  I used 2 of them in my application.  I was able to split the 
load into 2 banks of 50 coils and then powered each bank with one of the 
supplies.  It worked great!

Paul Duffy


----- Original Message ----- 
From: "Peter Todd" <pete@petertodd.ca>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Saturday, February 18, 2006 11:23 PM
Subject: Re: [EE] Linear power supply blowing it's diodes


> On Fri, Feb 17, 2006 at 07:31:09PM +0000, Sergey Dryga wrote:
>> > I'll place an order in the next day or two, meanwhile, anything I 
>> > should
>> > know about these supplies? I assume with my application I should be 
>> > able
>> > to simply hook them up and be done with it. Looks like they all have
>> > overcurrent protection, so no fuses needed. I don't see any mention of
>> > filter caps or such in the datasheet, so I assume they are relatively
>> > foolproof other than making sure they can still get airflow.
>> >
>>
>> If I remember correctly, in current configuartion PIC voltage is supplied 
>> form
>> the same power bus as motors.  This might cause glitches and random 
>> "reset" of
>> the PIC.  If you see some random problem, consider making a separate 
>> regulator
>> just for PIC.
>
> The motors are pretty small ones, and in previous testing things seem to
> be ok. That said, I did find out that a swift turn of the knobs they are
> attached too generates enough back-EMF to reset the individual PIC on
> the single motor control board. Unfortunately everything is connected to
> an I2C bus, so this invaribly crashes the whole bus. Interestingly the
> watchdog timer on the PIC fails too.
>
> Note that I did connect the the motor leads directly to the PIC ADC
> inputs, so there is a pretty direct route to the PIC. I have a ULN2000
> driving the motor, and I thought the inherent protection diodes in it
> would help... It worked on the breadboard, but the full circuit on a PCB
> didn't. Oh well, my current plan is to turn the whole shebang of motors
> on and off via FETs in series with v+ whenever the bus gets stuck.
>
> The other bit of weirdness is related to my bootloader setup... If have
> the master controller reflash the slaves on startup everything works
> fine. If I tell it to skip the reflash, and rely on what's already
> flashed, one or two out of the 64 slaves will fail to recieve any
> commands from I2C. Very odd, and which slaves fail to work changes on
> each reflash.  I've got a lot of debugging to figure out on that one...
>
> -- 
> pete@petertodd.ca http://www.petertodd.ca
> -- 
> http://www.piclist.com PIC/SX FAQ & list archive
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