# I can't figure this out! Reverse motor direction.

Discussion in 'The Projects Forum' started by amoore67, Mar 26, 2012.

Not open for further replies.
1. ### amoore67 Thread Starter New Member

Mar 26, 2012
3
0

I want to design a circuit that uses one momentary push button switch (spdt) to control a dc motor in both directions (it is a 5v dc system).

1. Hold the momentary push button, the motor turns one direction. Stop holding, motor stops.
2. Hold the same momentary push button again, the motor turns the opposite direction. Stop holding, motor stops.
3. Repeat 1...2...1....2...1...2..

I think this system will require some a flip flop switch of some kind. Maybe two 555s or something but I can't figure it out due to my lack of knowledge on the subject. Most circuits I find are constant but I don't want the motor to be constant I want it to be momentary or the motor turning for the duration the button is pressed. I realize this would be easy if I just used two buttons and an H bridge or if I use a toggle switch but that isn't what I am trying to do here.

2. ### wayneh Expert

Sep 9, 2010
12,101
3,033
I don't know if it'll help, but I recently worked on a polarity switching circuit using a 4017 counter. The counter output is either hi (source) or lo (sink). So if you compare the "1" output to the "0" output pin, you'll see the polarity reverse as the count advances. You'll want to reset on 1, I think.

The 4017 cannot likely drive your motor directly, so you'd need to put the output to a power op-amp in comparator configuration to give you enough current.

Oct 3, 2010
4,302
1,988

4. ### amoore67 Thread Starter New Member

Mar 26, 2012
3
0
A counter ic is something I am looking into. I need to figure out a formula that will give me decimal 0,1,0,2,0 and so on
or binary
00
01
00
10
00
and so on

As for an impulse relay, from what I have read it only has 2 positions, off and on where I need 3 positions. If wired as an H bridge the motor would always be running but I need it to stop. I want the motor to change with each press of the button for the duration the button being pressed down.
1. stop, button not engaged
2. motor turns right for the duration of the button held down
3. stop, button not engaged
4. motor turns left for the duration of the button being held down
5. stop, button not engaged
and so on

5. ### strantor AAC Fanatic!

Oct 3, 2010
4,302
1,988
The impulse relay is a latching relay that will change state on powerup, so each time you energize it, it will reverse the direction. it has Normally open contacts and normally closed contacts, just like an ordinary relay.

Check out this drawing here I did for someone else - he wanted the exact same operation as you describe. He was using an X10 home automation module and wanted that when the module activates it will open a cupboard door, and when it activates again, it will close the door. When the module is not activated, it does nothing.

Replace the X10 module contact with your pushbutton
Replace the actuator with your motor
replace 12V with 5V.

6. ### Wendy Moderator

Mar 24, 2008
20,765
2,536
Her is the problem. In this thread you spelled out this was an automotive problem.