Dc motor reversing

[kwame]

Hi folks
this is the best technology forum on the planet.
Does anyone know how of any hardware/device that can used with a two timers to reverse a twelve volt Dc motor automatically .
Most electronics hobbyist know that an alternative is using a DPDT toggle switch but this needs to operated manually.
Does anyone have an idea about how to do this?

 

[MikeMl]

Are you trying to move something between two fixed positions. If so, you really need to have limit switches in addition to a timer.

 

[Jaguarjoe]

An H-bridge can electronically switch a motor from one direction to the other. You could use an 8 pin microcontroller or other parts like 555 timers to control the H-bridge. Be aware that many H-bridges have disallowed states such as both inputs high together which will create smoke.

 

[kwame]

Expl

The motor in question is 12v DC electromechanical linear actuator with inbuilt limit switches, potentiometer.
The only problem is how to reverse the polarity of the motor automatically to reverse the motor in opposite directions at regular periods when i m away.
Can H -bridge do the job?

 

[crutschow]

An H-bridge or a DPDT relay.

 

[kwame]

An H-bridge or a DPDT relay.

How do i go about it using the DPDT relay?How would the schematic look like?

 

[crutschow]

How do i go about it using the DPDT relay?How would the schematic look like?

The same as you would a DPDT switch (see this).

 

[Jaguarjoe]

A DPDT relay will not provide a neutral, or idle state, the motor will always be running one way or the other unless power to the motor itself is interrupted. There is no braking either.
It is easy though.

 

[MikeMl]

A DPDT relay will not provide a neutral, or idle state, the motor will always be running one way or the other unless power to the motor itself is interrupted. There is no braking either.
It is easy though.

If it has limit switches, then it will interrupt itself.

Wire up a 555 as a free running (but slow) multi, say 60sec on, 60 sec off. Have it drive a DPDT relay as a polarity reverser. At each reversal, the motor will run until it trips the limit switch on the opposite end. Nothing will happen until the relay reverses again...

 

[kwame]

One thought

Thanks for all the advice;this is the best technology forum in the world!
I hope i can substitute an electronic or analogue timers for '555' or 'free running' stuff.Do i need a relay board for DPDT relay in this case?I guess not.
I want to install a toggle switch for the motor as well.I hope this will no do no harm to the setup.
How do i wire the toggle switch?
Thanks for all the support

 

[MikeMl]

Do you have a commercial timer with a DPDT relay output?

 

[kwame]

The timer i have has a small relay on which is SPDT relay.
Can i remove the SPDT from the relay board and replace with DPDT relay without damaging it?

 

[crutschow]

The timer i have has a small relay on which is SPDT relay.
Can i remove the SPDT from the relay board and replace with DPDT relay without damaging it?

That's difficult to answer without knowing what the relay board looks like and your level of soldering ability. If you did that, you would want a relay with the same coil voltage rating and close to the same coil current.

It may be simpler just to use the SPDT relay to power the coil for the DPDT relay.

 

[kwame]

Technology education

Hi folks
I studied liberal arts in secondary school/high school but now i have realised i have received a calling to become a technologist.I have written to a lot of technology trade colleges/schools virtually none of them replied my mails.
Friends,kindly help me find a trade school located in the US,CANADA or Belgium Italt etc which very is affordable and does admit foreign students from Africa because .
I want a trade school which can polish my know how in such areas as process control,pneumatics,welding,HVAC and allied subjects; with opportunities for students to undertake practical internship.
Kwame

 

[KeepItSimpleStupid]

Generally the control signals are DIRECTION and NOT ENABLE. Dynamic braking can be implemented using either an "H" bridge or relays. I've done just that.The NOT ENABLE RELAY would short themotor windings when at rest. The Direction is a DPDT reversing switch. States are OFF(brake)/ FWD/REVanda don't care

 

[blueroomelectronics]

Hi folks
I studied liberal arts in secondary school/high school but now i have realised i have received a calling to become a technologist.I have written to a lot of technology trade colleges/schools virtually none of them replied my mails.
Friends,kindly help me find a trade school located in the US,CANADA or Belgium Italt etc which very is affordable and does admit foreign students from Africa because .
I want a trade school which can polish my know how in such areas as process control,pneumatics,welding,HVAC and allied subjects; with opportunities for students to undertake practical internship.
Kwame

Do they have a course in thread hijacking? Why not start your own thread?

 

[KMoffett]

kwame,

Can't help on the school front...been too many years since I looked...what do see as "affordable"? Here in the US, many schools are full to overflowing with student applications. For many people, if you cant find a job in the current economy you go to, or back to, school.

What are the time periods you need between reverses?

Ken

 

[kwame]

I want a time period of one hour between reverses.
I am thinking of using a DPDT relay timer for the reversal but ia m a bit confused about the wiring ;most timer relays have about eight pins behind which makes it pretty confusing as DPDT toggle switch have six pins behind.

Kwame

 

[KMoffett]

8 pins on a DPDT relay: 2 pins for the coil, and 6 pins for the DPDT switch contacts.
One hour reverses: mains plug-in wall timer with an AC DPDT relay...or a mains plug-in wall timer with a wall wart and a DC DPDT relay.

Ken

 

[kwame]

Dc motor reversing (2)

8 pins on a dpdt relay: 2 pins for the coil, and 6 pins for the dpdt switch contacts.
One hour reverses: Mains plug-in wall timer with an ac dpdt relay...or a mains plug-in wall timer with a wall wart and a dc dpdt relay.

Ken

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