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Topic: DC/DC 3V to 5V Step Up Converter (Read 318 times) previous topic - next topic

czu001

I am currently running an ESP32 board which has an output of 3V.  I need to integrate with the following part:

https://www.adafruit.com/product/828

It requires 5V and has a max current draw of 15mA.  Can anyone suggest either a DC/DC converter I could use or should I go about building my own?  If I am to build my own, could someone please point me in the right direction as far as parts required?  I will be driving the logic from a GPIO pin from the board.

I would also be open to switching power from the main source (it will either be a 9V battery or some AA's).  Thanks!

jremington

Pololu has a nice selection of inexpensive, high quality step up modules.

Wawa

How is your ESP32 board powered.

If powered by USB, then power the sensor (red wire) from a 5volt pin of that board.
You just need to drop the signal output voltage (yellow wire) with a divider (two resistors) to <=3.3volt.
Leo..

czu001

Thanks for link!  I will likely be using a lithium cell to power the Arduino.

czu001

How is your ESP32 board powered.

If powered by USB, then power the sensor (red wire) from a 5volt pin of that board.
You just need to drop the signal output voltage (yellow wire) with a divider (two resistors) to <=3.3volt.
Leo..
Could you elaborate on that a bit for me?  The only two components that require power are that water flow meter and the 3.3V ESP32 board.  The power will be coming from a battery, but I haven't picked one yet.

I'm fairly new to electronics.  If I were to drive the board and meter with a 9V battery, you're saying to use a voltage divider to provide power to both the board and meter?  Would I then use a MOSFET to switch power between the meter and the battery?  Thank you!

Wawa

What ESP32 board (there are many).
Can it be powered with a single lithium battery, or must it be powered with 5volt.

Forget about a 9volt smoke alarm battery.
Leo..

ChrisTenone

...
I'm fairly new to electronics.  If I were to drive the board and meter with a 9V battery, you're saying to use a voltage divider to provide power to both the board and meter?  Would I then use a MOSFET to switch power between the meter and the battery?  Thank you!
No. Do not use a voltage divider to reduce the power for your components. Only use a divider to get voltage for sensors, or other places that there will be a small current draw. In order to get enough power for even an Arduino, you will be essentially running power down the drain.

If you need 3.3 volts, consider using 2 aaa batteries, or for 5 volts, 3 batteries. If you use lithium aaa cells, the voltages will be almost spot on.
I'm not disparaging the differently abled. It's just that thirty years of community college has literally made me mentally retarded.

czu001

Thanks for the input!  Here's the ESP32 board I will be using.

https://www.adafruit.com/product/3269

From what I'm reading, you really want to match the voltage as close as possible to the board requirements.  Given that particular board and the water flow sensor component, is a step-up converter for providing power to the component a good idea? 

The component uses a hall counter to provide pulses via interrupt to the board.  Will I also need a resistor to reduce the voltage from the component into the board?

Wawa

#8
Jun 21, 2018, 12:28 am Last Edit: Jun 21, 2018, 12:34 am by Wawa
I see a 1117 voltage regulator (1volt dropout).
That means a single lithium battery is out.
This board needs 5volt.

Battery power?
You must have had a good reason to pick the ESP32 over the lower power ESP8266.
What was it.
Leo..

wvmarle

Those water meters work fine on 3.3V (the cheap ones I bought from China look exactly the same and most likely are the same). They use a hall effect sensor to measure the flow.

They're also pretty bad for use with batteries. The hall effect sensors take 2-4 mA (the 15 mA is the maximum output current they can deliver - you normally draw near zero current when attached to an input pin, they're push/pull so no need for pull-up resistor), that will drain a common 18650 LiPo in about 1,000 hours or about a month by itself. For battery power a reed switch based sensor is much more efficient, albeit a bit harder to read, and I haven't found any such small water flow sensors with reed switch - those are all flow switches.

That's before you add the power draw of your ESP32 (indeed, why that one for just a water sensor?), though that part can be reduced big time by using sleep modes. Do a bit of WiFi communication (power hungry) and you're changing batteries every week.

Your LiPo will need its separate low drop-out regulator (there are ones around that drop just 200-300 mV or even less) to power the ESP. You'll fry that chip with a fully charged battery producing 4.2V.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

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