Relays

This is how I reverse my Diamond Scale TT.  A simple DC circuit with a  momentary double pole, double throw, center off, cross over switch.  Same could be applied to a double pole double throw relay. 

The center two terminals of this switch are hooked to the turntable DC drive motor.  Red left, Black Right.

Power feed is to the bottom two terminal, (white left, red right) note how the wiring continues with the cross over to the top two terminal.   Red left, white right.

Switch one direction counter clockwise, other direction clockwise.  Momentary switch  returns to the center position.

Change one of your power switches to a DPDT switch to reverse the polarity:

Thanks Rob, but what I was referring to was a relay that can be used in a radio controlled circuit.  The relay would be housed in the animated item along with the radio receiver & power supply.  I have seen the solid state type, but when purchased they never seem to come with a wiring diagram.  

Dan,

Regardless of what type of relay you use, it must have DPDT (Double Pole Double Throw) contact arrangement, also called 2C, where C is SPDT (Single Pole Double Throw). The relay will operate the same as the switch Rob illustrated, above.

Here is an example of a relay contained in a DIP (Dual Inline Package), suitable for PCB (Printed Circuit Board). When the relay is not energized (OFF), power flows from the Power Supply through C (Common) to the NC (Normally Closed) contacts. When the relay is energized (ON), power flows from the Power Supply through C to the NO (Normally Open) contacts. (Excuse my interpretation of all the acronyms, but some readers may not be familiar with them, and I hate to read something when the meaning of an acronym is not provided, and I am left in the dark.)

Good luck!

Alex

Can you post an existing wiring diagram showing your batteries and voltage involved...as well as the exact radio receiver model number so we can look up its capabilities?

Ingeniero No1 posted:

Dan,

Regardless of what type of relay you use, it must have DPDT (Double Pole Double Throw) contact arrangement, also called 2C, where C is SPDT (Single Pole Double Throw). The relay will operate the same as the switch Rob illustrated, above.

Here is an example of a relay contained in a DIP (Dual Inline Package), suitable for PCB (Printed Circuit Board). When the relay is not energized (OFF), power flows from the Power Supply through C (Common) to the NC (Normally Closed) contacts. When the relay is energized (ON), power flows from the Power Supply through C to the NO (Normally Open) contacts. (Excuse my interpretation of all the acronyms, but some readers may not be familiar with them, and I hate to read something when the meaning of an acronym is not provided, and I am left in the dark.)

Good luck!

Alex

So it looks like power is always on either way.  What would the diagram look like if there was a center off, so to speak, position on the relay ?

stan2004 posted:

Can you post an existing wiring diagram showing your batteries and voltage involved...as well as the exact radio receiver model number so we can look up its capabilities?

Here is one type I use frequently

http://www.ebay.com/itm/DC-12v...?hash=item20fc2d1113

Dan,

For ON/OFF plus Forward and Reverse operations, you would indeed need the third position. There are relays that would step through three (or more) positions, but those are a totally different devices. For the ones we are considering, two-position relays are the ones commonly available. You could use two relays (with two remotes) -  one for ON/OFF, and one to reverse direction.

Also, judging by the relay picture in your link, it appears that it has SPDT contacts, and the fact that it has only five connections would substantiate this observation - two connections for the relay power, and three connections for the contacts; common, normally open, and normally closed.

One possible approach -

Buy a separate DPDT relay (plain relay), connect it and operate it with your remote relay for direction control, and buy another remote relay for ON/OFF.

Alex

I'm thinking using a Lionel E unit. Somebody help me out on useing dc to energize the coil. It will work but maybe experiment with the voltage.

Here's how they work ...

http://www.olsenstoy.com/cd/b123%5C001305.pdf

And how much current you think that they will handle? 

And how do the electronic E units work? Anyone have a schematic?

Here's my 2 cents:

The "simplest" solution will be to use a 2 channel transmitter instead of the 1 channel you have linked.  The same seller that was linked for the 1 channel has the 2 channel units for $7.50.  This gives you an A and B button on the remote, and two relays on the receiver board.  From there you can connect the "B" relay to a third DPDT relay following the diagrams posted above for reversing the flow of electricity.  Then connect the feed Positive side of the DPDT relay through the "A" button's relay.  This will give you A button for on/off, and B button for direction change.  

As a note I couldn't find a DPDT relay symbol on the program I used, so I stacked two relays to represent this.  In effect it the same as two SPDT relays that turn on and off at the same time, so you could go that way as well.  

Moving on to more complex solutions, for about the same price you could continue to use the single button remote, and add a $2 Arduino and a 2 channel relay board.  With the right programing you would have operation of button pushes of "Push- On(forward), Push-off, Push-On(Reverse), Push-Off."  (As a note, this could also be done with discrete circuitry or some latching relays, but the Arduino is just way simpler.)  

Costs are about the same either way, just depends which you like better, two buttons or one.  

JGL

(Edited error in relay naming from DPST to SPDT)

I'm with JGL's first method.  Use the 2-button remote version and 2 of your existing receiver relay modules (or get a 2-channel receiver relay).   One button activates the accessory, the other button selects the direction.  Note the receiver modules you link to have the ability to set the mode of operation to "momentary" or "latching" (they call it "inching" or "self-locking").  For activation you set the corresponding receiver to "momentary" mode so the accessory motor runs as long as you hold down the button.  For direction you set the corresponding receiver to "self-locking" mode where the relay toggles between on and off on each button press. 

There are DPDT relays on eBay for under $4 (free shipping) and includes a socket which can cut down on soldering hassles.  The wiring diagram would be as JGL shows.

JohnGaltLine posted:

Here's my 2 cents:

The "simplest" solution will be to use a 2 channel transmitter instead of the 1 channel you have linked.  The same seller that was linked for the 1 channel has the 2 channel units for $7.50.  This gives you an A and B button on the remote, and two relays on the receiver board.  From there you can connect the "B" relay to a third DPDT relay following the diagrams posted above for reversing the flow of electricity.  Then connect the feed Positive side of the DPDT relay through the "A" button's relay.  This will give you A button for on/off, and B button for direction change.  

As a note I couldn't find a DPDT relay symbol on the program I used, so I stacked two relays to represent this.  In effect it the same as two DPST relays that turn on and off at the same time, so you could go that way as well.  

 

Moving on to more complex solutions, for about the same price you could continue to use the single button remote, and add a $2 Arduino and a 2 channel relay board.  With the right programing you would have operation of button pushes of "Push- On(forward), Push-off, Push-On(Reverse), Push-Off."  (As a note, this could also be done with discrete circuitry or some latching relays, but the Arduino is just way simpler.)  

Costs are about the same either way, just depends which you like better, two buttons or one.  

JGL

John, are there some wires missing in your diagram ?   It's late and I'm tired, so I am struggling to follow the path of the electrons from the power source to the motor.  I presume "Motor connection 1 and Motor connection 2 are the two solder lugs on the DC motor.  The 12V symbol is the positive and the negative is the lower right symbol.  

Dan, if you ignore the second relay coil, it looks right.  Relay A turns power on or off, and Relay B provides the reversing function.  The two relays at the right are to represent one DPDT relay with a single coil.  I guess JGL didn't have the proper relay picture.

Ah, that's a bit clearer.  Thanks John.

GRJ has it down.  As I said right under the picture: "As a note I couldn't find a DPDT relay symbol on the program I used, so I stacked two relays to represent this. "  Ignore the unused coil on the relays on the right side.  OR, use two SPDT relays if you want and connect the coils together.  

As a side note, my MacBook that I typically use to get on the forum has died at the moment, (Cracked screen), so I won't be able to keep up on things here as often for a little while.  I'll still see replies in email, and if you need some more help I can be reached by email.  

JGL

(Edited error in relay naming from DPST to SPDT)

Actually, if the receivers have SPDT contacts, you don't need any relays, just two receivers.

Normally both sides of the motor are tied to +, so the motor doesn't run. Pressing either button ties one or the other side of the motor to - , making it run in either direction. Pressing both buttons ties both sides to -, so the motor stops.

JohnGaltLine posted:

 

OR, use two DPST relays if you want and connect the coils together.  

PLCProf posted:

...Pressing both buttons ties both sides to -, so the motor stops.

And somewhat violently!  I like your idea but depending on the motor/accessory, when you short the windings on a rapidly spinning motor it brakes suddenly often throwing the load or whatever is being driven off the rails so to speak.  So it would be a your-mileage-may-vary situation.

The original method simply removes the voltage from the motor (without shorting the windings) so the motor and load spin down to a stop rather than slam the brakes.

stan2004 posted:

PLCProf posted:

...Pressing both buttons ties both sides to -, so the motor stops.

And somewhat violently!  I like your idea but depending on the motor/accessory, when you short the windings on a rapidly spinning motor it brakes suddenly often throwing the load or whatever is being driven off the rails so to speak.  So it would be a your-mileage-may-vary situation.

The original method simply removes the voltage from the motor (without shorting the windings) so the motor and load spin down to a stop rather than slam the brakes.

That is a point. 

Oh, well.....

Yes, I did mean SPDT, not DPST.  I had a case of the dumb and apologize.  Previous posts have been edited. 

I also thought about simply using the two relays as PLCPROF shows, but figured that operation would be more complex that way.  For the cost of an extra relay it seems worth it to have an on off and direction, as opposed to having to sort through which way the buttons are pressed. 

JGL

JohnGaltLine posted:

...

I also thought about simply using the two relays as PLCPROF shows, but figured that operation would be more complex that way.  For the cost of an extra relay it seems worth it to have an on off and direction, as opposed to having to sort through which way the buttons are pressed. 

Not sure I understand your comment.  PLCPROF method seems simpler to me.  You press button A to make motor run FWD, you press button B to make motor run REV.  

OTOH with the external DPDT relay acting as a direction switch, the relay toggles on each press and now the operator must "remember" which direction it was last set when activating the motor.  Some of these receiver modules have a little LED showing its relay is closed...but in a remote control application where the accessory is some distance away (and apparently the OP has an outdoor layout) it may be difficult to see this direction indicator.  Of course with our engines, the diesel's directional headlights or steamer's tender backup light indicates which way the motor will turn when you crank up the throttle!

I'm sure there are some accessory applications where the sudden motor braking might be acceptable...or even desirable.  For example with steam engine smoke fan motors the windings are shorted to instantly stop the rapidly spinning DC motor to generate distinct "puffs" of smoke.

Well, (to partially redeem myself) you could wire two DPST relays so one was forward and one was reverse. The NC contact on one of the receivers could be used to lock out the other relay to prevent shorting the battery when both buttons were pressed. Then you would have a forward and a reverse button without the braking effect.

An extremely simple wireless remote control direction reversing circuit can be made with a transmitter and receiver cobbled out of a $10.00 toy car and a DPDT latching relay. I've used this technique in my simplified wireless loco control systems.

Here's a quick sketch I made for operating a switch drive in my garden railway.  The Switch drive is either an LGB or Piko product.  They both work on DC.  Well, not exactly.  The LGB drive uses half wave AC if you wire it using their EPL system, but it will work on short bursts of DC.  The 14.8 volt Li-on battery will be used to power the switch drives.  The 12 volt power supply will power the receiver.

Please let me know if you see something that shouldn't be.