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Topic: Need help dividing analog voltage (Read 208 times) previous topic - next topic

anjaleen

I am using a pulse sensor (https://pulsesensor.com) connected to an Adafruit Feather Huzzah esp8266 board. It draws power from a 3V pin ("the output from the 3.3V regulator that can supply 500mA peak"), and sends the sensor values to the ADC pin. However, this pin has "a 1.0V maximum voltage." I am trying to create a voltage divider but don't know how to go about it. Any help/a diagram showing how to wire this voltage divider on a breadboard, would be greatly appreciated.  :smiley:

MarkDerbyshire

Search Google for Voltage Divider.  There are loads of examples and calculators available

MarkT

[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

edgemoron

3.3V----/\/\/\/----/\/\/\/---+----/\/\/\/----GND
                   1k              22k         |          10k
                                                   |
                                                 1.0V

newuser

http://www.ohmslawcalculator.com/voltage-divider-calculator

Enter R1 to have 30 kOhms and R2 to have 13kOhms to get 0.998 V

RIN67630

I am using a pulse sensor (https://pulsesensor.com) connected to an Adafruit Feather Huzzah esp8266 board. It draws power from a 3V pin ("the output from the 3.3V regulator that can supply 500mA peak"), and sends the sensor values to the ADC pin. However, this pin has "a 1.0V maximum voltage." I am trying to create a voltage divider but don't know how to go about it. Any help/a diagram showing how to wire this voltage divider on a breadboard, would be greatly appreciated.  :smiley:
Forget the voltage divider.
Use analogReference(INTERNAL) and you will get a range of 0..1.1V at the analog inputs. By the way that will be more independen from Vcc as well.

Wawa

Forget the voltage divider.
Use analogReference(INTERNAL) and you will get a range of 0..1.1V at the analog inputs. By the way that will be more independen from Vcc as well.
None of that on an ESP8266.
It only has one analogue input with a range of ~0-1volt.
Leo..

RIN67630

None of that on an ESP8266.
It only has one analogue input with a range of ~0-1volt.
Leo..
Then, where is the problem?
The sensor delivers 0..1V the ESP needs 0..1V.

jremington

Quote
Then, where is the problem?
The sensor delivers about 3.3V.

RIN67630

The sensor delivers about 3.3V.
OK, then 27KΩ and 10KΩ according to the common E12 values will provide 0..3,7V range.

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