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Turtle ConnectionsFrom SPCoast
[edit] Connecting the Turtle to the TortoiseJ-Tortoise (the 8-pin connector) on the Turtle daughterboard connects "1 to 1" with the 8 pins on a Tortoise switch machine. The Turtle daughterboard PCB can connect to either an 8pin 0.156" edge card connector or to an 0.156" Molex™ connector. [edit] Edge Card Connector
The benefit of using the edge card connector is that you do not need to modify the Tortoise. The downside is that the connector is expensive, hard to find, and is somewhat unreliable - it is easy to accidentally shift it or even pull it completely off the Tortoise. It is also easy to separate the two for service and testing. [edit] Molex Connectors
Al alternative mechanism is to solder right angle Molex pins to the Tortoise and use a mating connector on the daughterboard. The benefits include a strong, solid connection that can still be taken apart for service and testing. [edit] Soldered
If you have no need or desire to disconnect the daughterboard from the Tortoise, it can be soldered directly to the Tortoise with a straight 8-pin male Molex connector as illustrated at right. [edit] Configuration jumpers on the Turtle DaughtercardThere are four jumpers on the daughterboard; one is used to bypass the optional trackside "poor man's signalling" when it is not used; the others control the relationship between the control signal, the turnout position & feedback and the frog polarity.
[edit] Jumper Adjustment procedureThe Turtle defaults to Normalizing the turnout, so the first thing to do is to set JP-2 so that the points are in the desired Normal position. If JP-2 is "backwards", the turnout position will be opposite from what is desired. Once this is done, set JP-3 to match JP-2. If JP-3 is "backwards", the feedback indications will be reversed and your computer feedback or signalling logic will be confused. Finally, JP-4 sets the frog polarity to match the route chosen; if the overcurrent lamp lights up when an engine goes thru the turnout on a proper route, "reverse" the jumpers on JP-4. A Circuitron Tortoise has two SPDT switches built into it; one uses pins 2,3 and 4, the other 5,6 and 7. One is used for reporting absolute point position via JP-3, the other is used to change the polarity of the frog via JP-4 for live frog/power routing turnouts. [edit] "Poor Man's" Trackside Signals
The motor drive circuit is brought out to the J-Sig connector, where it can be used to drive "poor man's signals" for the turnout. The Tortoise is current limited to 15mA, which happens to be the "right" current for a bidirectional LED. With a 12v Tortoise drive power supply, you can wire 6 LEDs as shown and place them next to the turnout as a simple substitute for a more complicated (and more expensive) signaling system, at the expense of slowing down the point movement. When the turnout is Normal, the point signal is green, as is the normal frog-side signal; the diverging frog side signal is red. When the turnout is thrown (Diverging), the point side signal is yellow, the normal frog side signal is red, and the diverging frog side signal is yellow. This won't keep you from having collisions or from trailing the switch, but it can at least warn you! If you are not using these "poor man's signals", place a jumper on "Jumper 1"; nothing needs to be connected to J-Sig. [edit] Connecting the daughtercard to the main board
A daughterboard connects to the mainboard via a simple 8-conductor cable with RJ45 modular connectors. The cable is wired "straight thru", such that pin-1 on both ends is the same color conductor. A properly wired cable will look like a longer version of this (note that one end is upside down compared to the other). [edit] Connecting the Turtle to the TrackThe following description presumes that the turnout's "North" stock rail is gapped for detection as shown by the markings in the following diagrams. The Turtle can drive the frog of a power routing turnout by using a one of the builtin SPDT switches in the Tortoise. In conjunction with JP-4, it will apply either the N and S rail power to the frog based on which direction the turnout is thrown. Because it is possible for a locomotive that enters a trailing point switch which is thrown against it to cause a short, some sort of protection is required to give fault isolation from the booster's auto shutdown feature if you don't want to shut down your whole layout when it happens. This can be done in either of two ways: [edit] Insulated Frog Turnouts
Use an "insulated" or "dead" frog (aka "all rails live") turnout that doesn't have this problem. The Turtle daughterboard can be simplified if you are using insulated-frog turnouts; no frog wiring is needed, nor is the tail lamp or JP-4. [edit] Live Frog Turnouts
Use an automotive tail lamp placed in series with the frog power lead to act both as a visual alert and as a circuit breaker (it lights up and limits the current when a short happens). The Turtle daughterboard has provisions for such a bulb. [edit] Track Connections
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