stuck in motion

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tinkrman54

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I am a newbee to this forum so please be patient. I need help with a circuit I want to make using a small 3 volt dc motor connected to a timer. I am using a programmable timer that uses 2 AAA batteries to operate and outputs 3 volts dc to a to a 3 volt dc motor. The original function of the timer is to rotate the motor in one direction then the timer is set to rotate the motor in the other direction. This is done by alternating the dc output to the motor from positive to negative. This is where my problem starts.
I need more torque from the motor. I found that if I apply 6 volts to the motor for the duration that I need (aprox 3 sec) I get the torque I need. How do I make a circuit that will use the alternating 3 volt output from the timer and use a separate 6 volt battery source to the motor so the motor will rotate forward and backward. Do I use relays and diodes? I'm stuck with the motor turning in the same direction. Any ideas would be a help me.
 
I guess the simplest way is using the timer circuit as it is and connect a relay to its output, having the relay switch 6V to the motor.

There are no specifications given for the timer circuit. So it might fry applying 6V of supply voltage to it.

Boncuk
 
The problem I am having is being able to switch the polarity of the 6 volts needed to run the geared motor. The original function of the timer and motor was to open a plastic flap at a specific time and close the flap at a different set time but because I need the extra torque, I have to be able to use the 3 volt positive and negative output from the timer to power a relay or circuit.
 
Hi tinkrman54,

if you can get a 3V relay this circuit will do. Otherwise the timer output must be used to drive a transistor which will activate the relay using 6V.

I've drawn the schematic how to wire the motor. and also what the relay contactors do for CW and CCW rotation.

Use caution when connecting the diode across the relay coil. The cathode of the diode must be connected to +. Otherwise it will fry.

Boncuk
 

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If I understood tinkrman54 correctly, the original circuit has a bridge output. It is not clear from your drawing that one terminal of the relay coil needs to go to GND, and the other terminal to one of the outputs. The coil (and diode) must not be connected across the bridge output.
 
The way I understand the OPs request, he needs 6V for reverse and 3V for forward.

If there is already a bridge, I'd make the motor always see 6V and PWM forward at 50%, reverse at 100%. That would probably get pretty close. You might need to experiment with the PWM values to get the right behavior. If the reversing circuit is based on a relay, then I'd pull it out and sub in any of the inexpensive HBridge chips.
 
I need 6 volts to power the motor in forward and reverse directions. I can understand basic relay connections and basic transistor circuits.
Thanks, tinkrman54
 
I see that you have a diode across the relay and that you warned me about connecting the diode in the correct orientation because of the positive and negative voltage.
The original use of the timer that I am using operated a small 3 volt dc geared motor to open and closed a flap. There are two leads that come out of the timer, one red and one black. When the timer opened the flap, then the voltage on the red lead is(+) and the voltage on the black lead is (-). When the timer closed, then the red lead becomes (-) and the black lead is (+). I can't use a diode if the voltage output from the timer alternates as I have previously described. Maybe what I want to accomplish can't be done.
Thank you
 
Perhaps you didn't understand, or didn't read, my previous post.
I wrote: GND (in this case) means the negative terminal of the battery. See the modified drawing below.
 

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Last edited:
Thanks Ron for helping me.
What do the gray numbers signify? Is the relay that you drew reflect a stdp?
Thanks Tinkrman
 
tinkrman54 said:
Thanks Ron for helping me.
What do the gray numbers signify? Is the relay that you drew reflect a stdp?
Thanks Tinkrman
Click to expand...
Boncuk originally posted that schematic. I just modified it to show you how to connect your relay correctly (I hope ). I think the gray numbers are pin numbers of the relay he selected in his schematic drawing program. Perhaps he can elaborate, if necessary.
 
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