3pdt to dpdt

[kwame]

Using the NC contacts presupposes that the motor must move when there is no power supply.How?
for the motor to reverse the circuit must latch so that the motor is always connected to power.The limit switch will be switch the motor off /on in both direction.

 

[KeepItSimpleStupid]

Using the NC contacts presupposes that the motor must move when there is no power supply.How?

No power - no. A relay has TWO states ON and OFF. You wanted TWO states FWD and REV. When the relay is powered it is in one state, when unpowered it's in the other.


Follow the current. Travel the path from the positive terminal of the battery, through the relay to the negative terminal of the battery. Changes the state and do it again. Note the direction the current flows in the motor.


Dispense with an actual motor. Put a voltmeter where the motor would go. Note the polarity change when the relay changes state.

I also stated that cassette motors generally have a built-in speed control and therefore won't reverse.


The diodes I added make the limit switch(s) directional. One limit switch for each direction.

 

[Reloadron]

OK, to better understand this lets first look at the relay contacts. You have a 3 pole double throw relay (3PDT).

Pin 1 is the Common for pin 3 Normally Open and Pin 4 Normally Closed. Pin 6 is the Common for Pin 7 Normally Open and Pin 5 Normally Closed. Pin 11 is the Common for Pin 9 Normally Open and Pin 8 Normally Closed. Three sets of double throw contacts, N/O and N/C and each with their own Common.

You may want to print the relay drawing.

With the relay de-energized:

The positive motor power flows through pins 5 and 6 (Normally Closed) contacts of RY1. This applies a Positive to Connection 2 of the motor. At the same time, the negative motor power flows through pins 4 and 1 (Normally Closed) contacts of RY1. This applies a Negative to Connection 1 of the motor.

With the relay energized (12 volt power applied to pins 2 and 10):

The Positive motor power flown through pins 3 and 1 (Normally Open now closed) contacts of RY1. This applies a Positive to Connection 1 of the motor. At the same time, the Negative motor power flows through pins 7 and 6 (Normally Open now closed) contacts of RY1. This applies a Negative to Connection 2 of the motor.

The remaining relay contact set is unused, however, could be used if one wanted lamps or LEDs to indicate motor rotation such as Forward / Reverse or if a linear actuator was shimming In / Out.

The relay configuration is very, very common and used frequently for reversing a motor. Since I can't see your layout and connections I can't guess why it will not work. So here you have a detailed explanation of how it works.

<EDIT> I see KISS is up and about. </EDIT>

Ron

 

[kwame]

Plaudit!

Hi Ron ,KISS .......
thanks for all the encouragement and your persistence.Finally i made the breakthrough and successfully reversed the motor with the same relay.
Ron ,Your first circuit was 90% correct ;i made a little modification to it:The power supply to the relay coil and the NC and NO contacts must not be tied together or in series.I wish i could provide you with the revised drawing but save browsing the net i m an ignoramus when it come to computers .
Ron ,the first and second circuits you posted is precisely not the relay i am using.I am actually using Omron standard 3PDT Omron MK3P-I relay with mechanical indicator.
Cheerio!
Wisdom kwame Samlafo

 

[kwame]

RON
Pin 1 is the common for Pin 5 (NC) and Pin 4 (NO) whiles pin 3 is the common for pin 7(NC) and pin 6(NO).Pins 2 and 10 are meant for the relay coils. Wire the two common wires from pins 3 and 1 to the motor.Now two wires(12V DC) must be connected to two NC contacts eg Pin 5&7 and the motor will begin to turn clockwise in direction as long as the relay coil is de-energized.
Next,another wire must be wired from Pin 7(NC) to pin 4(NO) and wire a new from pin 5(NC) to pin 6 (NO);then simply energize the relay coil and the motor begin to turn counterclockwise and vice versa.

 

[kwame]

Any questions welcome !

 

[Reloadron]

RON
Pin 1 is the common for Pin 5 (NC) and Pin 4 (NO) whiles pin 3 is the common for pin 7(NC) and pin 6(NO).Pins 2 and 10 are meant for the relay coils. Wire the two common wires from pins 3 and 1 to the motor.Now two wires(12V DC) must be connected to two NC contacts eg Pin 5&7 and the motor will begin to turn clockwise in direction as long as the relay coil is de-energized.
Next,another wire must be wired from Pin 7(NC) to pin 4(NO) and wire a new from pin 5(NC) to pin 6 (NO);then simply energize the relay coil and the motor begin to turn counterclockwise and vice versa.

Kwame

While the models vary slightly with features the pin out was the problem. Attached are a few images of an Omron MK3P5-S which is a 3 Pole Double Throw 12 volt coil relay. Though not identical to yours as to features it functions identically. Note the pin out. This is the relay you have. and this is the data sheet for the relay you have.

Now if you scroll to the bottom of the data sheet we will see where the problem was. Note the pin out for the MKS3P(I) which is identical to what you have. Now note the pin out for the MKS3P(I)-5. The latter is the pin out for the relay I used in my circuits. I even included a pin out drawing. There was nothing wrong with my circuit, the problem was that you had a relay with a different pin out. While there was a my bad in there I would have thought you would have caught the pin out difference, it's on the relay.

I am pleased it finally works as advertised. Now wasn't that fun? I am even more pleased we now both understand why my drawing wasn't working with your relay.

Ron

 

[kwame]

Yes Ron
that is the relay i am using ,you are right.Dont eat all the hot dogs!All the best.

 

[Reloadron]

Later & have a good one.

Hey, hot dogs are like a food group to me. They must be all beef (that is essential) and they must be casing type and not skinless. They should also be placed in a real bun and not those cheap cake like buns. A damn good roll to compliment an all beef casing hot dog.

Ron

 

[KeepItSimpleStupid]

Ron:

Good detective work. I though we both knew what assume means. For those that don't know, put a space before and after the "u" in "assume". Once, confronted with something that didn't work and I asked if it was plugged in. The answer was "No!".

 

[Reloadron]

Ron:

Good detective work. I though we both knew what assume means. For those that don't know, put a space before and after the "u" in "assume". Once, confronted with something that didn't work and I asked if it was plugged in. The answer was "No!".

While I do drink I swear that damn relay fiasco made me drink even more. It just didn't make any sense to me. It was like, how the hell can it not work? Then when Kwame posted the pin info I was like what the hell? Then it clicked. Yeah, at my age I should have a handle on Ass-U-Me.

Ron