I have this built on my breadboard and seems to be working but I’d love to get some quick validation on the setup to ensure I’m not missing something.
In short I want to drive X number of Air pumps where each air pump needs 3.5-6.5V. I need to change the voltage of the air pumps from 3.5 - 6.5V (max load is 270ma). I’m using an external power supply (9v DC wall adapter rated at 1A). The DC adapter is connected to the board and lights up the rail for the motors. It is also connected to a linear voltage regulator to drop the voltage to 5v to power the Particle. I’m using 9V b/c the regulator requires a min of 2.2V over 5V to get 5V out. With my breadboard if I drive lower than 9v the Particle doesn’t power on b/c of the voltage drop from the regulator to the VIN pin.
My main questions:
Is this the proper way to power the motors and Particle? I have a capacitor on both sides of the regulator to clean up the power.
Is the circuit for the motors correct and is it missing anything? I drive a PWM signal to the base of the transistors. That PWM controls how fast the pumps operate by opening up the gate to allow the higher 9V to flow through the transistor. I have a capacitor across the motor to soften the PWM signal and a diode to prevent inductive flyback when the motor is turned off.
When I do the PCB design I end up with ratsnest lines that I can’t get rid of… If I remove the ratsnest lines it removes the power wires from the 9v rail to the motors.
I’m still a noob and trying to understand if this is created correctly and if its missing anything that should be included or changed.
Also, where/how would one find an EE (for pay) to help finalize this design?