Dc motor reversing

[carbonzit]

thanks kenny!
Now i want to install an override rocker/dpdt switch .

Meaning you want to be able to manually reverse the direction regardless of the relay position?

Piece of cake. Just wire in a DPDT switch "downstream" of the relay (between the relay and the motor). You can put in as many as you like; each one simply reverses the wires. (Think of the cross-wired DPDT switch, including the relay contacts, as "electrical wire exchangers".)

 

[KMoffett]

#1....only my mother gets to call me "Kenny".
#2....what did you do?...timer/AC relay?...or...timer/wall wart/DC relay?

Ken

 

[kwame]

I used the AC relay

 

[kwame]

Hi carbon
you guessed right!

 

[KMoffett]

Just to expand on carbonzit's question...when you "manually" switch the direction, do you want it to stay that direction until you change it again (timer change is disabled), or do you want the timer to switch it in the opposite direction at the next hour.?

Ken

 

[kwame]

I Do not want it stay in that state permanently;i want the timer to reverse it as usual hourly.I want to use the override to test whether it is in working condition occasionally.

 

[carbonzit]

So what's important is that it reverse hourly, right? Doesn't matter which direction it's running in, so long as it reverses? Then the in-line DPDT switch will work fine.

 

[kwame]

So the override switch will not do any damage to the linear actuator?Can you explain vividly how i need to wire the over rid so that no damage is caused to the linear actuator.

 

[carbonzit]

Simply wire it in-line with the motor, like so:

**broken link removed**

All this does is reverse the two wires, so it won't damage anything.

However, caution: if the motor is running, this might not be good for it, if full power is applied and you suddenly reverse directions. I can't remember if you posted details about the motor.

 

[kwame]

Hi kMoffet,Carbonitz and everybody
i am not not familiar with Logic gates (i havent seen one be4) but I think using an 'EX-OR' logic gate will protect the actuator from damage .In that, in the event the timer and the rocker switch get activated simultaneously the actuator wont be activated .Because The 'Exclusive-OR' gate is a circuit which will give a high output if either, but not both, of its two inputs are high.
Will it work or not?

 

[KMoffett]

I don't think that simultaneous switching will damage anything. The actuator will just go to the position that the combined polarity of the relay and switch determines. The actuator's internal limit switches will prevent overrun in the wrong direction.

Ken

 

[mvs sarma]

this type of reversal is possible only on permanent magnet type DC motors

If the motor has exciter coil, then the best is to add a bridge rectifier across the input voltage and the dc pins of the bridge to the exciter coil, while he actual input is applied direct to running winding.

 

[kwame]

The motor is of the 'permanent magnet type' but i do not think it has an 'exciter' coil.

 

[kwame]

I don't think that simultaneous switching will damage anything. The actuator will just go to the position that the combined polarity of the relay and switch determines. The actuator's internal limit switches will prevent overrun in the wrong direction.

Ken

Hi Ken
when timer and toggle switch get activated simultaneously wouldnt the voltage jump to 24v ie 12V+12V and roast or even fry the 12VDC linear actuator?

 

[KMoffett]

You only have one 12V source. Reversing it doesn't give you 24V. All you are doing with both the relay and the switch is to reverse it twice. Though reversing it while it is running is not a good idea with any motor. When you manually reverse it is up you. Perhaps you can use a DPDT-center-OFF switch. Then you can stop it before reversing it.

Ken

 

[kwame]

Yes Ken i think you have driven the final nail into the coffin.I was also thinking using the DPDT switch with center tap facility.