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### Topic: Need help dividing analog voltage (Read 336 times)previous topic - next topic

#### anjaleen

##### Aug 13, 2017, 11:05 am
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.

#### MarkDerbyshire

#1
##### Aug 13, 2017, 02:13 pm
Search Google for Voltage Divider.  There are loads of examples and calculators available

#### MarkT

#2
##### Aug 13, 2017, 02:15 pm
24k + 10k perhaps?  That divides 3.4V down to 1.0V  https://en.wikipedia.org/wiki/Voltage_divider
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

#### edgemoron

#3
##### Aug 13, 2017, 11:28 pm
3.3V----/\/\/\/----/\/\/\/---+----/\/\/\/----GND
1k              22k         |          10k
|
1.0V

#### newuser

#4
##### Aug 14, 2017, 08:25 pm
http://www.ohmslawcalculator.com/voltage-divider-calculator

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

#### RIN67630

#5
##### Aug 15, 2017, 08:29 am
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.
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

#6
##### Aug 15, 2017, 12:59 pm
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

#7
##### Aug 15, 2017, 04:26 pm
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

#8
##### Aug 15, 2017, 04:47 pm
Quote
Then, where is the problem?