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Anool / clockthree

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HW: LDR Short Circuit #12

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
The LDR is not designed correctly.

I soldered up the circuit and got an repeated auto shutoff on the power supply.

Removing LDR fixed problem, but row driver #2 was fried.

When LDR is in full sun (low resistance) the only thing between VCC and ground 
is a 1K resistor ==> 5 AMPS.

Need to re-engineer this.

Original issue reported on code.google.com by wyojus...@gmail.com on 14 Dec 2010 at 3:25

GoogleCodeExporter commented 9 years ago

Original comment by wyojus...@gmail.com on 14 Dec 2010 at 3:35

GoogleCodeExporter commented 9 years ago 
... or we could not support the speaker.  Sounds kinda cheep.

Original comment by wyojus...@gmail.com on 14 Dec 2010 at 3:36

GoogleCodeExporter commented 9 years ago 
Something else is wrong here.
With a 1kOhm resistor across 5V supply, the current would be 5mA not 5A (=5 
Volts/1000 Ohms). Not enough to fry either Resistor or IC. There's a similar 
application shown in the book - Getting Started with Arduino. See the attached 
file.

Original comment by anoo...@gmail.com on 14 Dec 2010 at 7:18

Attachments:

GoogleCodeExporter commented 9 years ago 
Must have been something else.  Circuit works now, (but row driver still dead?) 
 Will close when complete system works.

Original comment by wyojus...@gmail.com on 15 Dec 2010 at 1:01

GoogleCodeExporter commented 9 years ago 
LDR works without shorting.  This issue is closed.

Original comment by wyojus...@gmail.com on 17 Dec 2010 at 12:45