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Topic: Powering bluetooth module from Arduino pro mini 5v (Read 1 time) previous topic - next topic

syntax_error

Hi,
I have a bluetooth module rated max at 3.3v, and an Arduino pro mini ATmega168, at 5v. When I power the bluetooth module through a resistor divider (1.2k +2.2k) I get around 1.68v only to the bluetooth module. Can somebody explain to my why this happens? Does anyone know how to power a 3.3v module from a 5v arduino?

Nick Gammon

Resistor dividers are not very good voltage regulators (the drop varies by the current drawn). Look up a proper voltage regulator circuit.

syntax_error

I didn't know that. As you can tell, I'm completly new to electronics -.- Thank you!!

Runaway Pancake

Try a couple of rectifier diodes (1N4001, 1N4002, etc.) in series.

Code: [Select]

                     |
+5----A_K----A_K-----| BT +V
                     |


Test circuit:
Code: [Select]

                     
+5----A_K----A_K-----| 470?|----Gnd
                   |
                   |
         check for 3V  here                   
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Docedison

That Circuit Might work, If regulation wasn't important (It will vary about 300 mV from no load to about 200 mA and it isn't very thermally stable, Diodes are commonly used as temperature sensors in IC's like Processors. After all there's a whole lot of diodes in a Processor. It is also missing a 47uF cap. No Power supply should ever be without some bypassing. The voltage will range from about 750mV @ 0 C to about - 500 550 mV @ 80 C @ 100mA current. Not a lot really considering digital electronics but more than enough to vreate problems with any linear circuitry.

Bob
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