LPD 8806 power questions
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LPD 8806 power questions

by slurry bowl on Sun Nov 18, 2012 9:40 pm

I have 1 meter of the strips and I know I should expect MAX amperage to be 2 amps.

I have a 12 V battery I recharge off the sun that is robust with a 42 Ah rating.

I want to power the Arduino and LPD8806 strip off of the battery and understand I need to bring the voltage down to 5 volts for both.

I have been experimenting with resistors in series to add voltage drop so that the voltage is right. Im not sure of the resistance of the strip and dont know what ohm value to have my resistor. Can anybody guide me on this?

WHen I experiment and think I have it close, the strip still appears to flash rapdily and is not consistent.

THanks for any wisdom, I really appreciate this forum
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Re: LPD 8806 power questions

by slurry bowl on Sun Nov 18, 2012 9:54 pm

The flickering was due to a lack of a common ground. ahhhh, DUH !

I am familiar with voltage dividers but never really understood them. thanks for any input
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Re: LPD 8806 power questions

by adafruit_support_bill on Mon Nov 19, 2012 6:24 am

I have been experimenting with resistors in series to add voltage drop so that the voltage is right. Im not sure of the resistance of the strip and dont know what ohm value to have my resistor.

:!: Resistors are NOT a substitute for a voltage regulator in this application :!: . You cannot use them to regulate voltage into a variable load such as a digital LED strip. Do not connect the strip to a 12v source without a proper voltage regulator or you will damage the strip.
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Re: LPD 8806 power questions

by slurry bowl on Mon Nov 19, 2012 11:54 pm

THANK YOU. I respect that resistors are not voltage regulators in the way required for this strip.

I found a car charger that plugs into a cig. outlet car adapter and now have a working 5 V source off of my battery. YES !

This is a bit cumbersome, what might be a better voltage regulator? Does Adafruit sell one for my 12 V battery?

THanks!
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Re: LPD 8806 power questions

by adafruit_support_bill on Tue Nov 20, 2012 6:59 am

We have these little gems which are good for up to 1A. http://www.adafruit.com/products/1065
If you expect to be running near max current (2A) you could put one at each end of the strip and cut the 5v wire in the middle.
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