Turntable Decoder

Fleischmann 9152 Turntable has up to 48 track exit positions and has a mechanical locking mechanism that allows to precisely position the bridge in each of the exits, a system similar to other of Marklin and Arnold. The turntable motor receives voltage for turning from the control switch that goes with it, but doesn't rotates until a coil mechanically unlatches a lever in the mechanism of the bridge that operates the switch . When turning the bridge, the lever switch remains closed, so you can stop applying current to the coil. When the bridge faced the next track exit, the lever comes into a hole and switches the engine off then the bridge will be properly aligned.

Digitally control of the turntable is relatively simple with a contact (relay) decoder type K84 as LDT SA-DEC-4

or the ESU Switchpilot with Switchpilot-Extension in the following way:

With accessory outputs we selected direction of rotation CW/CCW (the polarity of the motor) and with other accessory output, in one position we unlocked the coil of the bridge, so this will move until we change the position, time that the bridge will stop at the next exit track as in this example for Traincontroller

You can also perform that with a turnout decoder (pulse) adding a pair of latching relays (DSU):

Under the previous scheme, in one accessory address we select the direction of rotation (the polarity of the motor) and in other accessory address, in one position we unlocked the coil of the bridge, so this will move until we change the position, time that the bridge will stop at the next exit track

Sometimes it's hard to get latching relays so it can also be done with an turnout decoder, such as PpP-Des3 or ESU SwitchPilot programming fixed its outputs and with the MOT adapter and a normal relay.

You can also do in a simple way using a locomotive decoder as in this article that uses a ESU Lokpilot.

With previous circuits you can't direct the bridge automatically to a specific track output (indexing), or at least to the next, or rotate 180º the bridge with a single command. There are some circuits that allow it as Draai15 or the one from Stephane, others require making yourself the turntable as the Tapiola Parish Model Railway Club or like Jindra Fucik with a magnetic positioning system.

There are commercial decoders with indexing as the sophisticated Fleischmann Turn-control, but the most popular is the Marklin 7686/7687 or the DCC compatible LDT TT-DEC. For DIY you can look at FDC-DRS and Digital-bahn (or its new version DSD2010) although with this you need to make modifications in the turntable. They all use the Marklin 7686 commands so you can control it with any command station capable to drive turnouts and with the major part of computer control programs.

I designed the TT-F9152 decoder for my old 9152 Fleischamnn turntable to have indexing and control it manually or digitally (DCC or Motorola ) with Marklin 7686 commands.:

With the TT-F9152 decoder a turntable can be controlled manual and digitally, each actually existing track output can be accessed directly through the indexing capability. The bridge can be rotated to the next existing track output with a single step. It can also be rotated 180° with a single command.

Works in analog or digital (DCC or Motorola ), since it can be controlled and programmed from the three buttons on the control panel.

The decoder is capable of changing the polarity of the bridge to prevent short circuits when the bridge is rotated 180º and the polarity of the tracks do not coincide with the exit track. It also has an input to indicate when the bridge is on the track 1 and then can self-adjust the current position in the event of anormally disadjusting the bridge position.

The TT-F9152 decoder can be controlled digitally with DCC or o Motorola )accessory commands compatible with the Marklin 7686 so it can be used with the ECoS or with the most common railroad control programs (Traincontroller, Windigipet, iTrain ,...). It also has an optocoupled feedbak output that is active while the bridge is moving.

You do not need any modification on the turntable, only the original control switch is replaced by the decoder, you can have a small panel with three buttons and one LED for manual control of the turntable.

Programming in the decoder the actually existing track outputs (spoke), the output track 1, the accessory address range and how to access the spokes, is easily done using the command buttons or with the same Marklin 7686 decoder commands. You can also slightly change the rotation speed of the bridge.

Can be used with other turntables with the same principle of control as Arnold and Marklin.

In order to program the PIC you can download the HEX file. With ECoS use the Motorola version.

Download PCB, schematics and manual here in pdf format from Adobe, if you want to build your own PCB or identify componets see this tutorials.

Users have confirmed that they use with 48 outputs turntables 9152, 9152C, 6152, 6651C, Arnold 6381 and 24 outputs turntables Roco 35900 and DIY in the Atlas N:

Tim Marsh has adapted the circuit to be used with the Peco turntable or any other manual turntable and have 24 outputs. Uses a geared motor for a slow speed, a slotted disc and a pair of barrier optocouplers. Download this special version here (DCC)

TT-F9152 created by F.M.Cañada