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Motor Feather wing/DC motor
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Motor Feather wing/DC motor

by IoTAll on Thu Aug 01, 2019 11:26 am

Hi,

I have always been using the motor feather wing to drive DC motors in my projects.

In the project I do now, I need to drive a 5v small DC motor (400mA max) and I just need to switch it on and off at full speed.
I dont need to drive it backward or forward, dont need to speed it up slowly, I have only one motor.

I have now removed the motor wing completely and I am just driving the DC motor with the PowerBoost 1000 Basic - 5V USB Boost @ 1000mA from 1.8V+ (PRODUCT ID: 2030).
I have a M0 feather which is only controling the Enable pin of the PowerBoost 1000 Basic, to switch on and off the DC motor.

Are there cons to drive this DC motor this way, instead of driving it with the motor feather wing?

Thank you very much!

IoTAll
 
Posts: 133
Joined: Wed May 31, 2017 6:34 pm

Re: Motor Feather wing/DC motor

by adafruit_support_bill on Thu Aug 01, 2019 11:53 am

A couple of things to consider:
1) Motors and other inductive loads can create damaging reverse-voltage spikes. Motor driver chips have built-in protection diodes to protect the output transistors. It would be a good idea to incorporate one in your circuit to protect the boost converter output of the PowerBoost. The diode should be wired in parallel with the motor - but 'backwards' so that any reverse voltage spike is re-directed back through the motor. See this guide for an example: https://learn.adafruit.com/transistors- ... motors-7-9

2) Voltage boost does come at a cost: There will be a proportional decrease in current. And about 5%-10% of your power will be lost as heat.

If your primary supply is a 3.7v LiPo, then you do need the boost.

But you have access to a true 5v source, then a simple transistor or MOSFET circuit would be more efficient.

adafruit_support_bill
 
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Re: Motor Feather wing/DC motor

by jdelcamp11 on Thu Aug 01, 2019 11:18 pm

If motor speed isn't critical, you could use the bat pin thru a transistor. There would be a small voltage drop across the transistor. The battery would range from 4.2 to 3.0 if it isn't on external power, but would hang around 4.2 if on external power.
The motor won't turn as fast but it might be sufficient for your application.

jdelcamp11
 
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Re: Motor Feather wing/DC motor

by IoTAll on Mon Aug 19, 2019 1:52 pm

Thanks a lot!
I used only the Boost 1000 as it was convenient for me.
Works great, thanks a lot!

IoTAll
 
Posts: 133
Joined: Wed May 31, 2017 6:34 pm

Please be positive and constructive with your questions and comments.