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Electronics => Projects, Designs, and Technical Stuff => Topic started by: Tom18991 on December 06, 2023, 05:37:51 pm

Title: Detect when DC motor is running?
Post by: Tom18991 on December 06, 2023, 05:37:51 pm

Looking for advice on how to detect if a DC motor is running, using only its ground wire? No current flows when the motor is off.   I'd like to create a yes/no binary signal I can feed to a microcontroller -- high when the motor is running, low when it is not.  Is there a tried and true way to do this? 
Title: Re: Detect when DC motor is running?
Post by: soldar on December 06, 2023, 05:41:44 pm
No current is ever flowing on the ground wire. You mean "neutral"?
Title: Re: Detect when DC motor is running?
Post by: themadhippy on December 06, 2023, 05:58:44 pm
Quote
You mean "neutral"?
theres no neutral on DC
Quote
Looking for advice on how to detect if a DC motor is running, using only its ground wire?
low side current sensors  and a comparator?

Title: Re: Detect when DC motor is running?
Post by: TimFox on December 06, 2023, 06:06:27 pm
Do you need to check that the motor is not stalled?
The current is higher than normal under stall conditions with power applied.
Title: Re: Detect when DC motor is running?
Post by: soldar on December 06, 2023, 06:13:08 pm
Quote
You mean "neutral"?
theres no neutral on DC
I missed the DC part. My bad.
Title: Re: Detect when DC motor is running?
Post by: Benta on December 06, 2023, 06:58:25 pm
A glass tube reed switch with a coil wound around it. That'll even double as noise filter.
Title: Re: Detect when DC motor is running?
Post by: rcjoy on December 06, 2023, 09:04:09 pm

For industrial use, a DC current switch:

https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/current_-a-_voltage_sensors_(ac_-a-_dc)/dc_current_switches# (https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/current_-a-_voltage_sensors_(ac_-a-_dc)/dc_current_switches#)