I was wondering if anyone had any experience using a variable flow water pump with an Arduino. I know PWM only changes the speed of the pump, I am looking to change the amount of flow. Can anyone recommend a good one? I am relatively new to all of this but here is what I envision.
pump is on at medium flow until flex sensor is flexed
pump moves to high flow
through this entire process I will be using PWM to turn the motor on and off
Basically I am trying to create a pulse.
I also would not know how to code a variable flow motor. But that is a topic for another area.
Pump output is dependant on motor speed; both pressure and flow will change if you change motor speed via PWM.
Doesn't this give you the variable flow you require.
See here for details
Sorry for the delay in response I didn't realize that I had to turn notifications on for each thread. This is the pump I have. I don't necessarily have a budget but I'd like to create something that recreates a human pulse as cheaply as possible.
The flex sensor wouldn't change the rate. only the pressure.
v2.0 for pulser
60,000 milliseconds in a minute
average adult pulse is 80 bpm
60,000/80 = 750
750/2 = 375
pulse HIGH for 375 then LOW for 375
using PWM to use flex sensor to increase motor pressure
This is the Math I did to come up with my numbers. I have a feeling I am confusing myself even more with pressure and flow.
The gist is this, the pulse can be felt the entire time. When the flex sensor is flexed, the pulse can be felt better (since the vessels would be pulled closer to the top of the skin) I can probably do this mechanically by pushing the tube closer, if needed. Otherwise I wouldn't need to PWM it.
I've been trying to use a MOSFET I purchased from digikey but haven't successfully created the circuit. ( I am very new to electronics and unless the schematic is laid out on a breadboard I struggle.)
Thank you for the article, i'll read it right now.
The pump you have is described as having a 4-segment pump rotor. This would seem to give a quite regular flow, based on speed of the motor.
To actually get a "pulse" you need to have tubing that will expand and contract with the flow changes from the pump. That is the function of the blood vessels and why you can feel the "pulse" anywhere in your body.
I think as a beginning for your project, just turning the pump on for a time, then off for a time, will give you a pulse. Vary the tubing wall thickness and flexibility until you get the pulse you want. Then play with the ramp up and down in pump speed to shape the pulse as you would like it.