How to wire? 8AA 5cree
- Thread starter derek750
- Start date
hopkins
Enlightened
derek- google: Ohms law , Simple LED Circuits, Calculating resistor values.
Look at these AA battery discharge curves:
http://www.powerstream.com/AA-tests.htm
Those 5 Cree LED's when powered up properly (and heat sinked !!!)
will each measure 3.5volts across each one. And each will have
350mAmps of current flowing through it.
To drive 1 Cree you need a resistor of about 2.8ohms in this circuit
with 3 new alkaline AA batteries.
Try 9 AA batteries in a 3 x 3 x 3 configuration for output of 4.5volts.
Buy 5 resistors, so each Cree has its own resistor, and operates independently from the others but share the battery and switch.
Simple and safe.
Warning the battery pack will be draining at 1.75amps. Beware of melting
plastic.
So you will maybe get 20 minutes at full brightness
and then it will ramp down quickly (45min?- 60min?) to dimmness.
Alkalines suck when drained so fast.
Good luck and post a picture of your light when its finished.
DIY lights are great.
Look at these AA battery discharge curves:
http://www.powerstream.com/AA-tests.htm
Those 5 Cree LED's when powered up properly (and heat sinked !!!)
will each measure 3.5volts across each one. And each will have
350mAmps of current flowing through it.
To drive 1 Cree you need a resistor of about 2.8ohms in this circuit
with 3 new alkaline AA batteries.
Try 9 AA batteries in a 3 x 3 x 3 configuration for output of 4.5volts.
Buy 5 resistors, so each Cree has its own resistor, and operates independently from the others but share the battery and switch.
Simple and safe.
Warning the battery pack will be draining at 1.75amps. Beware of melting
plastic.
So you will maybe get 20 minutes at full brightness
and then it will ramp down quickly (45min?- 60min?) to dimmness.
Alkalines suck when drained so fast.
Good luck and post a picture of your light when its finished.
DIY lights are great.
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