FINALLY GOT BLUNAMI OPERATING COUPLER

Great work @BOB WALKER.

I see you are using the Blunami 2200.  I wonder if I use the 4408 and set the FX to a momentary button if I would need the relay or if I could do it direct?  I'd be using an MTH PS3 coupler which needs 5V to fire.

Ron

@Ron045 posted:

Great work @BOB WALKER.

I see you are using the Blunami 2200.  I wonder if I use the 4408 and set the FX to a momentary button if I would need the relay or if I could do it direct?  I'd be using an MTH PS3 coupler which needs 5V to fire.

Ron

Couplers draw much more than 100ma so you still need a relay. PS3 couplers are even lower resistance than Lionel or PS1 couplers.

You can also change the FX3 CV to the coupler CV to get the clank when you hit coupler.

Pete

So can I assume you need one per each coupler or can both couplers use one relay since only one is fired at a time?

If you want to operate one at a time you need two Function outputs and two relays. Consider the Blunami can supply 100ma @ 12-14v and the coupler is 5-8 ohms (PS2 or Lionel). That equates to 2 to 3 amps.
Bob, what are you using for relay power?

Pete

@Norton posted:

Consider the Blunami can supply 100ma @ 12-14v and the coupler is 5-8 ohms (PS2 or Lionel). That equates to 2 to 3 amps.

PS/2 and PS/3 couplers are 2-3 ohms, PS/1 and TMCC couplers are the ones that are 6-8 ohms and run on track power.

For coupler power I used the Blunami primary power source fed to the coupler via the NO contacts on the relay. The DIP relay has a 300ohm coil and is well within range of the FX current capability. For front and rear couplers, two relays and two FX's would be required. I wired up only the rear coupler initially, but almost never use the front coupler remotely, so may not get to it. I doubt that the Blunami could handle the coupler currents directly and don't want overload one. The relay approach is quite simple and is probably the best way to go.

John, I realize this is an old thread but is the track voltage converted to DC to actuate those PS1 and TMCC couplers?  I have several Atlas TMCC engines that I plan on converting to Blunami with the 4408 board.  I found some inexpensive relays to use that operate at 12 volts and use very little current that should work very well with the Blunami board.  I had planned on converting the Atlas engines to PS3 but changing the couplers is a pain.  Another quick question, is the PS3 5V supply for the couplers AC or DC?  Thanks.

Larry

You can fire a coupler with AC. PS1 couplers have essentially the same impedance as TMCC couplers. I use straight track voltage. The pulse is so fast it won’t damage the coil. Just make sure you have the Fx output set to momentary, otherwise the voltage will be applied continuously and burn the coil out.

Pete

Thanks, Pete.

Larry

You can use the TE Connectivity IM06DG relay to switch the function power from the Blunami.

I had originally done a board using the design Karl came up with for the coupler interface, but the Blunami 4408 has grounding that I was a bit worried about crossing.  That being the case, I decided to come up with a small board to conveniently wire the 12VDC relay to the function output.

I added a resistor in series in case you're running at significantly higher voltages than the 12V relay coil.  I suspect in most cases, you could just jumper this connection.  I also added a TVS to step on any kickback EMI from the coupler coil, just in case.

The board fully stuffed is 0.6" x 0.75" and about 1/2" tall.

John, have you designed a two (front & rear) coupler version?

John, would a 5 volt version of your board work with a PS3 board and TMCC couplers?  I have an Atlas GP60 that I have upgraded to PS3 and would like keep the TMCC couplers since it a real pain to modify the Atlas trucks to use the PS3 proto couplers.  Thanks.

Larry

@PSAP2010 posted:

John, would a 5 volt version of your board work with a PS3 board and TMCC couplers?  I have an Atlas GP60 that I have upgraded to PS3 and would like keep the TMCC couplers since it a real pain to modify the Atlas trucks to use the PS3 proto couplers.  Thanks.

Actually, since the PS/3 couplers are fired with a brief PWM pulse that is around 20V for 18VAC track power, I suspect the 12V relay would work fine.

The relay approach offers more flexibility than my transistor-buffer board.  With the relay, you can use rectified DC or track AC to fire the couplers.  There's something to be said for using track AC, as that is less likely to cause a momentary voltage drop to the Blunami card power input.  My inspiration for the transistor-buffer board was overcoming the current-sinking limitations of the Blunami 4408 board.  And my two converted locos run and uncouple without issue using my board.  But it's not the only way to do this.  The transient suppressor across the relay contacts on John's relay board is a nice touch.

@KarlDL posted:

The relay approach offers more flexibility than my transistor-buffer board.  With the relay, you can use rectified DC or track AC to fire the couplers.  There's something to be said for using track AC, as that is less likely to cause a momentary voltage drop to the Blunami card power input.  My inspiration for the transistor-buffer board was overcoming the current-sinking limitations of the Blunami 4408 board.  And my two converted locos run and uncouple without issue using my board.  But it's not the only way to do this.  The transient suppressor across the relay contacts on John's relay board is a nice touch.

After thinking about it, I went for safety.  I tend to do that with a lot of electronic control projects, many of my other projects feature lots of Opto-couplers and relays for the same purpose.  Many times the opto-coupling is really necessary, but a few instances I could have gotten away without it, but it makes me feel better.

I just got a little nervous when the feature output ground was not common with the common ground on the Blunami 4408.  I'm thinking it's likely just a diode drop away through a bridge rectifier, but I decided "safety first".

I decided to install a Blunami 4408 board and pull the PS3 board from the one engine I was going to use relays to fire the TMCC couplers.  I inadvertently actuated the PS3 board when the couplers were not connected and toasted something(s) on the board not too long after I had installed the board.   I got the relays wired in this afternoon and both couplers operate.  I had purchased 12 volt relays and had to wait for resistors to drop the 24 volts at V+ on the board to12V.   I took out the PS3 speaker and put the TMCC 8 ohm speaker back in the fuel tank.   I sure do like all the Blunami options for sounds and lighting.  I am waiting for chip LEDs to use as ditch lights and wire connectors for the LEDS in the shell.

Larry