Hello. I have a plan to install a panel with momentary push buttons hooked up to switch tenders from Micro Mark. I will also have LED's. What I would like to accomplish is for the momentary button to be pressed, turnout "switch tender" moves the turnout. At the same time, whichever way the turnout is pointing, "straight" or "diverging" a LED on the panel lights up. I will have a color for straight and a color for diverging. I have a re-purposed 300w pc power supply, modified to take advantage of the 12v, 5v and 3.3v rails.... So I have plenty of power for just about anything on this setup. thanks. Switch Tender Switch Machine, the best model train switch for realistic layouts, slow-motion switch mounted under the layout (micromark.com)
Are you asking how to accomplish this using the Switch Tenders? Unlike the Tortoise that has built in relays for controlling LEDs, this does not. But, the power is always on so it's just a matter of hooking your LEDs and resistors up to the same motor wires. This makes sense to me and since these machines are 6 or 7 dollars cheaper, I may try them as well. Thanks for bringing these to my attention.
Yeah, I was asking how to accomplish this. Thanks for the reply, as I will do as you suggest. Power is always on, so it's a matter of hooking up the resistors and LEDs to the motor.
There are members here who know a bunch about electronics and can help. I know a wee bit. The circuit is pretty simple, as LEDs are dependent on polarity. You'll just need a resistor to account for the maximum current in the motor drive circuit. I'm guessing the maximum current will be when the movement is complete and the motor stalls. These motors run all the time, right?
Another approach is to detect the pushbutton switch closure with an Arduino UNO or MEGA. I use many of these to control panel indicator LEDs and track signals. The programs are actually quite simple. The Arduino monitors the button push, determines the state of the switch, triggers the switch if needed (does not allow false changes of the switch), and changes the LEDs accordingly. I use quad and octo relay boards to pass the current to the switches (I use Atlas snap switches, or PECO switches with servos on the PECO units). The program protects the switches from excess current or holding the button down too long. It could be adapted to operate Tortise-type switches as well.
FYI, BTW, did you know that a "Touch Toggle Base" can do this as well? Check out their adapting LED Driver for Signals can not think of a simpler, more complete system to go (ps: am NOT "advertising for" but rather simply "shopping for alternatives" am currently using bulky, paralleled Atlas relays as well)
Thanks. I looked at the site. The only thing I suggest is increasing the resistor to at least 1kOhm or 1.5kOhm. I don't like running 10mA through the LEDs. By the way, two of the inventors of LEDs were friends of mine back in the day...! Yeah, I am an old guy... For relays, I use multi-relay boards that connect to Arduino or Raspberry Pi microcomputers. Cheap, functional and will switch a lot of current, and operate on 5V.
I suspect Berrett's snap-action-base does the same thing as it uses a charged capacitor to switch rather than powering directly. Question: Are most LEDs polarity dependent? Meaning they only light with current passing one way but not the other? Would a simpler, alternate signal control method also be, if using a DPST switch, to center connect the LED "+ -" then cross/reverse the polarity? With a two-light, red/green signal, one would then connect both lights in series? (ie: long LED +pos to short LED -neg lead thus only one lights at a time) +| |- 'X' jump from "power" (with + to 'turnout') -| |+ to LEDs (R or G is always 'ON") -| |+ from power to 'switch straight' (with '-' to a momentary switch ground) Would this work? Is a single resister "current direction dependant" as well?
Actually, you select the resistor based on how bright you want the LED, making sure you stay below the LED's maximum current. P.S. These can operate the same way as Tortoise switch machines (constantly powered, direction controlled by polarity) with one big difference: current draw. Tortoise switch machines draw about 15 - 16 ma. stalled, so they can be used as the LED resistor by being wired in series with the LEDs; however, Switch Tenders draw 60 ma., too much for typical LEDs, so the LEDs have to be wired in parallel with their own resistors.
To have the LEDs controlled by polarity, they have to be wired in parallel, not series. LEDs block reverse polarity, so if one is reversed and they are wired in series, neither LED will light no matter the polarity.
That can work with the reservations that Robert mentioned. I use a slip ring with my turntable to take 4 wires from below the turntable to the turntable as it turns. I wanted to control the track power, have a light in a shack on the turn table and two lights in the arch above the turntable bridge. Lots to control with only 4 wires considering you need 2 wires for a circuit. 2 wires send the DCC track current to the track on the bridge and inside the bridge is a AC to DC circuit that turns a white LED on in the arch anytime there is current to the bridge track (it can be turned on/off). The other 2 wires are for the light in the shack and the 'flashing' red warning light up in the arch. The circuit like the other one and the rotation of the table are controlled but two Arduino's. For this circuit when the shack light is on the current flow one way through the wires to the two lights (above right). When the hand controller rotates the table the current flows the opposite way and goes on and off for the flashing effect. It al works well. As Robert mentioned there are resistors (not shown above) that regulate the current and light intensity for the LEDs. There is more about that part of the build ( HERE )...... and a video ... . Sumner
Hi All LEDs are diodes. Think- "like a one way gate". So, yes, they are polarity dependent. Your question focuses on running one diode in reverse bias all the time- not great for LED lifetime. Running the diodes in series- it will not quite work like you want. Putting the LEDs in series "nose-to-nose"- one diode will look like a high resistance and drop most of the voltage across it, and limit the current to the reverse bias current limit (in the microamp range until failure). Resistors are not polar.
How are you planning on keeping the motor stalled in each direction when you release the push button ?? Normally you would use a toggle switch to reverse the motor polarity and keep it powered, as shown in the instruction sheet: In order to use push buttons with a stall motor, you will need to add a latching relay or similar device to keep the motor powered after you release the push button. To add LED indicators, I would recommend putting them in parallel with the motor. You may also need to put a capacitor across the motor leads, to prevent the LEDs from damage when the motor polarity is reversed. Another method for adding LED indicators would be to use a separate micro switch, actuated by the turnout throw bar. With this method the LEDs can be on a separate power supply and thus not damaged by the high voltage spike when the motor is reversed.
Lots of good points and after looking at them the switch machine doesn't seem to be quite the bargain it appears to be at $16. Add the 3PDT toggle switch they recommend to control the stall motor and frog polarity at another $6 and you are over $20 and still haven't addressed how to use push buttons and/or latching relays for the stall motor if you don't run the toggle switches. For about $10 you can have a servo switch machine that can be adjusted so that the points aren't overpower and route LEDs. You will spend about 20-30 minutes at the soldering station but nothing overwhelming and you don't need an Arduino or computer to control the servos ( HERE ). Sumner
I suppose another option would be using 3PDT toggles. Two rows to work polarity reversal on a DC stall switch motor and the remaining row to illuminate the LED position indicators. Newark 1M31T6B11M1QE.
Yep, that is what Micro-Mart recommends but theirs adds another 6 to the cost. They say use it for the frog polarity if that is required (for me I want that) but as you mentioned it could be used for the LEDs instead or both if the layout is DC. That wouldn't work on a DCC layout though. You would have to use it for one or the other. I know stall machines have been around for a long time and work but when you can buy a servo for $2 and also have the option for how far it throws and how hard it pushes the point against the stock rail maybe they should be in the conversation. Lot of pluses with a servo and they don't have to be powered all the time. Sumner
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