Hello,
I need to be able to test a pump using a range of voltages. The signal pin takes a voltage signal between 0.06 - 2.75 VDC. This signal is used to control the frequency of the pump. My question is: how can I manipulate voltage to this range and control it within the range? I was thinking voltage regulators, but it will not let me change voltage in a range.
This is the pump I am working with:
BPV1500-AnalogTecnical-datasheet.pdf (1.6 MB)
Thank you
It is not to power the pump, it is a analog control signal. You need a DAC. Some boards have a DAC, but you can also buy one: https://www.adafruit.com/product/935.
With a 5V Arduino board, the DAC might output a voltage of 0...5V. It is no problem if only half of that is used for the pump.
The ESP32 has 8-bit DACs. That is safe, because it is maximum 3.3V, and the common ESP32 boards have a onboard voltage regulator of 3.3V.
The Raspberry Pi Pico has no analog output as far as I know, but it can output a PWM signal at such a high frequency that it is almost analog and only a small RC filter might be needed.
The Arduino MKR Zero has a 10-bit analog output.
The problem is the stability of the signal. If you power a Arduino from a USB cable, then the voltage varies. If the DAC output varies accordingly, then there is no stable output.
How much and why? I have not encountered any special issue powering an Arduino from USB 5 volts, either because I am connecting to the big rig or just using a phone charger cube.
a7
Hi,
Which model do you have?
Can you post the pump model number please?
Tom.. 
Wow, I was thinking too much. A DAC makes a lot of sense.
Model Number: V1500-B3C12V
You might be satisfied with the analogWrite() PWM followed by a low pass filter, a poor man's d/a solution.
a7
Do you need micro controller control?
That system lends itself to just a manual potentiometer control.
I/O X
This is a general I/O connected to an A/D converter of the microcontroller inside the pump.
The default functionality is frequency control:
• 0 – 0.05 V DC: Maximum frequency of the pump
• 0.06 – 2.75 V DC: Frequency control of the pump
• 2.75 – 2.85 V DC: Pump stops
• Max input voltage: 3.3 V DC (the pump can be damaged if exceeded)
Tom..
PS. Looking at the datasheet, it looks like the electronics are pretty weak, so many do not exceed voltage warnings otherwise you damage it.
If you use a uno , just put a CR filter on a PWM output , job done.
Google !
The external DAC from Adafruit has a output up to VCC. If the 5V from the USB varies with 10% and it is a 5V Arduino board and that external DAC is used, and that external DAC is powered with 5V, then the output varies also 10%.
As I see it, just slapping together a few components will result in this worst-case situation.
I agree with alto777 and hammy, a PWM output with a RC filter would do the job.
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