Model Train Electronics
Turnout Switch Control Board
NOTE: Turnout control switch not included
One major source of electrical failures is in the wiring of a reversing double pole double throw switch (DPDT) for controlling a switch motor. Especially if you are using a micro switch. It can be difficult to get all the wires in place and neat.
To help prevent failures and increase reliability we developed a small circuit board that takes care of the cross wiring.
The normal way someone wires a switch for controlling a turn out, you have to wire a cross (X) on the back and attach two in and two out wires. This works but it can be difficult to wire on the small miniature switches and is often a source of errors and shorts.
With our switch board you solider the micro switch to the PC board and connect your two in and two out wires. Clean and simple. There is no difference between the two sides, either side can be in or out.
We provide three solider pads for each wire (PinA1and A2, Pin B1 and B2). This allows you to chain the power in down a line of switches. If you are controlling a pair of switches you can run a pair of wires to each switch machine from the switch board.
I like Push Button on-on DPDT switches. I use the Philmore 30-005B. This board should work with any miniature switch.
The board is designed with common in the center two pins, pins 2 and 5.
Turnout Switch Control Board with Lockout
NOTE: Lockout switch included, Turnout control switch not included
There are times when you would like to "lockout" (disable, bypass) a control turnout switch. One example is with train module layouts. If you have turnout controls on both sides of your module, if one side is "public" and one side is "private" you might want to lockout the public side. This board is your answer. The function of the board is the same as the Turnout Switch Control Board above with an added lockout switch on the circuit board.
When you set up your module, from under the module, throw all the lockout switches on the "public" side of the module. The turnout controls on that side of the module are now "locked out". If someone from the public flips a switch, nothing happens, your trains are safe.
The lockout switch "bypasses" the turnout control switch. When you engage or disengage the lockout switch the turnout might change position. You should check all turnout positions after you engage or disengage the lockout.
Tech Details
Here is the tech details of what the switch board is doing. The left drowning is the schematic of a the switch. The right drawing is the schematic of board wiring.
In the position shown the purple wire connects to the blue wire and the black wire connects to the green wire.
When the switch is thrown the other way, the purple wire connects to the green wire and the black wire connects to the blue wire.
Lockout schematic is shown in the normal mode.
When the Lockout Switch is thrown, the reverse switch is locked out (bypassed). The purple wire is connected to the light blue wire that connect to the dark blue wire on the far side of the reverse switch. The black wire is connected to the dark green wire that connects to the light green wire on the far side of the revers switch. This "Locks Out" (by passes) the reverse switch.
Switches
We have found that not all Micro Switches have the same spacing or the same pattern for the contacts. Our boards are designed for a switch where the center pins (2 & 5) are the common pins.
We have two different contact spacing, the holes in the board. The spacing of the two columns is the same at 0.19" (4.85mm), but he contact spacing in the rows is different. The original boards (old) were designed around the Philmore 30-005B (I have found this listed as MS-197 or MS-197K). On these switches the row spacing is 0.14" (3.5mm).
Using needle nose pliers we have "adjusted" the solder lugs on the "new" switches and got them to fit into the original boards. This is not the best, so we developed the new board with different hole spacing.
NOTE: When ordering please specify the hole spacing needed.
Here are some of the model numbers of switches that clients have uses. For a toggle switch, you want a 2 position toggle, on-on, not an on-off-on (center off). For a push button you want an on-on, not an on-(on) (this is a momentary switch), sometimes called a latching push button. In General a toggle switch is much cheaper than a push button.
- Philmore 30-005B, Push Button, old spacing 0.14"
- Push Button MS-197, Old Spacing 0.14"
- Jameco 317472 (I believe 21979 has a center off, it is makred as on-none-on not on-off-on so not sure), Toggle, New Spacing 0.19"
All Electronics MPB-177, Mini DPDT Push Button - Push-On / Push-Off, New Spacing 0.19"All Electronics is closing 8/2023All Electronics MTS-8PC, DPDT ON-ON Mini Toggle Switch, Spacing ?All Electronics is closing 8/2023- NTE Electronics, Inc, 54-393 Push Button - Found these on Digikey, I believe the spacing is 0.14", I have not bought any to test them.
- NKK Switches Push Button Part Number MB2085 or EB2085, These should work, I think they are 0.19" spacing. Here is the data sheet from DigiKey MB2000Bushing.pdf
Switches
This whole contact spacing issue can be very confusing. If you only need a few switches, shipping from an electronics place can be expensive. My answer is to stock a small supply of both Push Button Switches and Toggle Switches. You can buy a complete set Switch Board and either Toggle or Push-Button, or Switch Board with Lockout, Lockout Switch, and either Toggle or Push-Button. I will be sure to send the correct Switch Board to fit the contact spacing on the Toggle or Push Button switch.
Other Electronics From My Friends
Michael Larson designed a replacement for the UP5 the Free-mo Throttle Panel (FMTP). It has a number of special features built in just for the module model railroad community. The FMTP combines the same network features of a Digitrax UP5 or NCE UTP with the added functionality of:
- a full-time battery-saver voltage on the front two panel jacks (for Digitrax throttles)
- an adjustable DC voltage output (labeled DC_OUT) available for running turnout machines, lights, and other animation on your module
- a completely isolated and separate track status LED (labeled DCC_IN)
The FMTP may be used in a Digitrax-based system and mixed with UP5s, or an NCE Pro Cab-based system mixed with UTPs. The FMTP is not compatible with and should not be used with NCE Power Cab systems.
For more information on the FMTP see Michael's (Southern Western Rail Systems) Etsy listing for the FMTP https://www.etsy.com/listing/960037082/the-free-mo-throttle-panel-fmtp
Special Thanks
Special thanks to Chad Stalsworth (Bif Ditch Designs) for doing the PC Board layout for these boards and to Michael Larson (Southern Western Rail Systems) for the lockout idea.
Ordering
To place an order send an email to orders@prawndesigns.com . Include a list of what you want to order (Part Number and Description) and your shipping address. We will get back to you with an estimate of when we will have your order is ready to ship and shipping costs.
Some items are available in the Prawn Designs Etsy Store.
Please read the Laser Cutting and Engraving FAQ page for details on laser cutting and engraving side effects.
| Part Number | Title and Description | Price | Image |
|---|---|---|---|
Train Electronics |
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PD-21027 |
Turnout Switch Control Board, (1 to 5)Only need one or two, this is the way to buy them. Specify 0.14" or 0.19" contact spacing.
Mini switch NOT included. |
$1.25 each |
 |
PD-21028 |
Turnout Switch Control Board, (6 to 11)If you need 6 to 11 this is the right part number. Specify 0.14" or 0.19" contact spacing.
Mini switch NOT included. |
$0.75 each |
|
PD-21029 |
Turnout Switch Control Board, (12 or more)Buying 12 or more, this is the best price. Specify 0.14" or 0.19" contact spacing.
Mini switch NOT included. |
$0.50 each |
|
PD-21040 |
Turnout Switch Control Board, with Lockout (1 to 5)Only need one or two, this is the way to buy them.
Specify 0.14" or 0.19" contact spacing.
|
$3.50 each |
 |
PD-21041 |
Turnout Switch Control Board, with Lockout (6 to 11)If you need 6 to 11 this is the right part number.
Specify 0.14" or 0.19" contact spacing.
|
$2.10 each |
|
PD-21042 |
Turnout Switch Control Board, with Lockout (12 or more)Buying 12 or more, this is the best price.
Specify 0.14" or 0.19" contact spacing.
|
$1.40 each |
|
PD-21045 |
Turnout Switch Control Board and DTDP Mini Toggle Switch (1 to 5)Includes:
|
$7.50 each |
 |
PD-21046 |
Turnout Switch Control Board and DTDP Mini Toggle Switch (6 to 11)Includes:
|
$4.40 each |
|
PD-21047 |
Turnout Switch Control Board and DTDP Mini Toggle Switch (12 or more)Buying 12 or more, this is the best price. Includes:
|
$3.00 each |
|
PD-21048 |
Turnout Switch Control Board and DTDP Mini Push-Button Switch (1 to 5)Includes:
NOTE: The button is now black not red. My source for latching DPDT Pushbutton Switches closed. I cannot find a resonable price from another source, if you know of one please let me know. |
$28.00 each |
 |
PD-21049 |
Turnout Switch Control Board and DTDP Mini Push-Button Switch (6 to 11)Includes:
NOTE: The button is now black not red. My source for latching DPDT Pushbutton Switches closed. I cannot find a resonable price from another source, if you know of one please let me know. |
$16.00 each |
|
PD-21050 |
Turnout Switch Control Board and DTDP Mini Push-Button Switch (12 or more)Buying 12 or more, this is the best price. Includes:
NOTE: The button is now black not red. My source for latching DPDT Pushbutton Switches closed. I cannot find a resonable price from another source, if you know of one please let me know. |
$10.00 each |
|
PD-21051 |
Turnout Switch Control Board, with Lockout and DTDP Mini Toggle Switch (1 to 5)Includes:
|
$10.25 each |
 |
PD-21052 |
Turnout Switch Control Board, with Lockout and DTDP Mini Toggle Switch (6 to 11)Includes:
|
$6.10 each |
|
PD-21053 |
Turnout Switch Control Board, with Lockout and DTDP Mini Toggle Switch (12 or more)Includes:
|
$4.10 each |
|
PD-21054 |
Turnout Switch Control Board, with Lockout and DTDP Mini Push-Button Switch (1 to 5)Includes:
NOTE: The button is now black not red. My source for latching DPDT Pushbutton Switches closed. I cannot find a resonable price from another source, if you know of one please let me know. |
$28.00 each |
 |
PD-21055 |
Turnout Switch Control Board, with Lockout and DTDP Mini Push-Button Switch (6 to 11)Includes:
NOTE: The button is now black not red. My source for latching DPDT Pushbutton Switches closed. I cannot find a resonable price from another source, if you know of one please let me know. |
$16.00 each |
|
PD-21056 |
Turnout Switch Control Board, with Lockout and DTDP Mini Push-Button Switch (12 or more)Buying 12 or more, this is the best price. Includes:
NOTE: The button is now black not red. My source for latching DPDT Pushbutton Switches closed. I cannot find a resonable price from another source, if you know of one please let me know. |
$10.00 each |
|
