Hi all, new on here and hoping that someone will help me.
I want to run a motor in one direction, only for a second, using a momentary switch, then again in the opposite direction using the same switch. It is a small 12v motor very low current.
I am sure similar has been asked before and I have seen something using a couple of 555 timers, or a single 556 and two relays but cannot find it again.

 

Is it in here? http://forum.allaboutcircuits.com/blog.php?b=190

 

Thanks for the pointer. I should say that I have zero experience and know nothing about electronics in comparison to you guys, but I have a desire to learn.
I guess what I am after is using the timers as monostables, but its the single momentary switch to control it all that causes the difficulty.

 

Hi all, new on here and hoping that someone will help me.
I want to run a motor in one direction, only for a second, using a momentary switch, then again in the opposite direction using the same switch. It is a small 12v motor very low current.
I am sure similar has been asked before and I have seen something using a couple of 555 timers, or a single 556 and two relays but cannot find it again.

So if I understand your first post -

1. turn on switch
2. motor runs in direction "A" for 1 second
3. motor then runs in opposite direction, until switch is shut off

Is the above sequence what you want to do? How close does the '1 second' have to be?

 

So if I understand your first post -

1. turn on switch
2. motor runs in direction "A" for 1 second
3. motor then runs in opposite direction, until switch is shut off

Is the above sequence what you want to do? How close does the '1 second' have to be?

Hi Shortbus
Very close, what I want to achieve is

1. Momentary press switch
2. Motor runs forward for 1 second
3. Momentary press same switch
4. Motor runs in reverse for 1 second

The 1 second is not critical, its to push/pull a lock motor and can be controlled with limit switches at both ends of travel.

Thanks for your help

 

I think you should decide first if it can be controlled or if it will be controlled via limit switches.

If limit switches are present you actually don't need a monostable.

 

Thanks Praondevou, my thouht was that it can be controlled by the limit switches if needed. The single momentary switch would be the controlling element.

 

Praondevou is right it can be done with just the limit switches, and that eliminates the chance of burning up the motor.

I found you a circuit if you want to do it with some chips and limit switches though.
http://www.robotroom.com/Flip-Flop-74HC74-Back-And-Forth-Robot5.html

 

Thanks for your efforts Shortbus, that looks good but, will that not keep reversing direction every time one of the switches is pressed? what I am after is
1 brief press of s1
2 motor runs forward max 1 second, can be cut with limit switch
3 motor stopped
4 brief press of s1
5 motor runs backwards max 1 second can be cut with limit switch
6 motor stopped

Sorry if I wasnt clear in earlier post, I have found lots of circuits using more switches but I can only have 1.

 

I have a flip/flop circuit using one PB and two relays for picking up the motor and reversing it.
Plus a couple of diodes and caps.
I have used it in the past in place of a S.S. circuit where a relay is needed anyway.
You would need the limit switches though.
I can dredge it up if interested?
Max.

 

Maxheadroom...Yes please, certainly worth a look to see if it will do.
Thanks

 

This does what you want. The relay needs to be one with low coil current. A small signal relay will do it. The flipflop just toogles between one state and the other every time you press the momentary button. The relay then switches and reverses the motor direction. The motor movement is stopped solely by the limit switches which are normally closed,i.e. they are closed whenever the motor is not in its end position.

If you can live with a toggle switch instead of a momentary button you could remove the relay and flipflop. If this is battery powered you will want something without a relay, it will consume to much current.

 

Thanks Praondevou, looks ok other than current consumption because as you mention it is battery powered. It does need to be a momentary push switch as well

 

Ok then use a single coil latching relay like this one: http://www.digikey.ca/product-detail/en/V23079B1203B301/PB1085-ND/1633971

The output of the FF that goes low will trigger the connected 555. The timer makes sure the relay is only powered as long as is needed to switch it in the other direction. It stays there until the other 555 is triggered , when you press the button again. The schematic is not complete as see, the components around the 555s and some connections on the FF are missing.

 

Here is the relay version I have used the circuit with a couple of OMRON MY4 relays, any other type may need an adjustment of the R & C, the original circuit had 6 pole relays which in that case you can eliminate the 3rd relay C.
Max.

 

Cheers Max, I may have to knock up a trial version of that and have a play.
Really appreciate the advise from all, I am indebted to you.

Dave

 

The original circuit had 6 pole relays with 175ohm coil and 75μf cap and 23ohm resistor.
This was purported to be tested over 2000 operations at 12/sec!
I couldn't imagine pushing the button that fast!
Circa 1962.
Max.

 

Cheers Max, I may have to knock up a trial version of that and have a play.
Dave

BTW, you have to be careful with the terminology, I got into deep water when I first used that expression when I first came to Canada, It has an whole different connotation here.
My neighbor did not want to be late for work so I told her I would knock her up in the morning!
Max.

 

My neighbor did not want to be late for work so I told her I would knock her up in the morning!

And how did that work out for you?

 

When I found out later, I was glad her husband was not there.!
Max.