Automatic polarity reversing relay

Thread Starter

stokes760

Joined Jul 17, 2024
6
I have a dc motor with internal limit stitches. I'm trying to find something I can trigger with a timmer. The timmer will run long enough for the motor to hit limits. Then next timed event the polatity will be automatically switched to run motor opposite direction. Then next timed event ect ect. Anything simple I can use?
 

crutschow

Joined Mar 14, 2008
38,322
The H-Bridge driver can be made using either transistors or a relay,
Which to use depends upon how often you need to reverse the motor, and how long the system will run.

You will also need a toggle flip-flop circuit to reverse the direction with each timer pulse.

Do you have a timer circuit?
 
Last edited:

crutschow

Joined Mar 14, 2008
38,322
A new thought--
You can avoid the requirement for a FF circuit if you make the timer on-time and off-times equal to the time between reversals.
Thus when the timer output is high, the motor will run in one direction until it stops, and then, when the timer output goes low, it will run in the opposite direction until it stops.
Many timer modules can do that.

What is the motor's operating voltage?
 

Thread Starter

stokes760

Joined Jul 17, 2024
6
A new thought--
You can avoid the requirement for a FF circuit if you make the timer on-time and off-times equal to the time between reversals.
Thus when the timer output is high, the motor will run in one direction until it stops, and then, when the timer output goes low, it will run in the opposite direction until it stops.
Many timer modules can do that.

What is the motor's operating voltage?
24v and about 100watts
 

Thread Starter

stokes760

Joined Jul 17, 2024
6
Are the timing event durations the same each time?
The motors take a little longer to roll up vs down. But internal limits handle the stops. Ideally the motors would roll down 5am up at 630am roll down at 630pm and up at 830pm. The motors take approx 10 minutes to run
 

LowQCab

Joined Nov 6, 2012
5,101
stokes760

Please state the actual problem You are trying to solve,
rather than asking how your idea for a solution to the problem might possibly be accomplished.

All of the particular details matter, including the "whys" for using them,
as well as any Spec-Sheets for Components that You may already have,
and pictures would be an added bonus.
.
.
.
 

Thread Starter

stokes760

Joined Jul 17, 2024
6
Can you program one so its output on-time is for the motor duration in one direction and the off-time for it to be in the other.
No that would be simple they are just switched on for x duration then off. Ideally I can find something that would be inline of the power susply and motor that every time the ac timer powered the dc power susply ot would automatically reverse polarity.
 

MrAl

Joined Jun 17, 2014
13,667
I have a dc motor with internal limit stitches. I'm trying to find something I can trigger with a timmer. The timmer will run long enough for the motor to hit limits. Then next timed event the polatity will be automatically switched to run motor opposite direction. Then next timed event ect ect. Anything simple I can use?
Hi,

I do not think I would use a timer here. Linear motion can be error prone for various reasons, and the errors can integrate over time. That means after it runs for some time it could crash into one of the end borders. If you do use a timer, don't ditch the limit switches. They are there to protect the mechanics.

You might be able to give a better explanation of what you are doing though.
 

ElectricSpidey

Joined Dec 2, 2017
3,312
Hi,

I do not think I would use a timer here. Linear motion can be error prone for various reasons, and the errors can integrate over time. That means after it runs for some time it could crash into one of the end borders. If you do use a timer, don't ditch the limit switches. They are there to protect the mechanics.

You might be able to give a better explanation of what you are doing though.
I don't see how the OP can do what they want without using a timer.
 
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