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    Is there a way to make these are bit more robust. Seem to fry at the slightest thing. Had two go because the yellow wires touched a positive 16v dc feed

  • #2
    We have worked at this to protect the signals from sudden spikes in supply (They are more common than I ever imagined) and new batches should be more robust.

    Dapol Staff Member


    • #3
      Joel Dapol,
      and interested parties. Problems and possible design solutions.

      How the signals currently operate.

      Fundamentally the Dapol range of signals use a tiny motor to mechanically operate the signal arm. But as the signals also have an LED to illuminate them, this has resulted in a not to clever method of operating the system (in my opinion). A constant supply either 14v AC or 9-12v DC via the black and red wires, provides the power for the motor, (when activated), and constantly to the LED.

      So the two yellow wires which must NOT be connected to a power supply, because they are only the "activator" for the motor, and must be connected, to a "Momentary" contact type of switch to trigger activation of the motor mechanism.

      Current problems with the system provided.

      This system, as it stands, unfortunately means that there is no way to prove the signal arm has moved, and in which position the arm is in. Further on all TEN of the signals I bought for my layout, I quickly discovered when testing these signals, that it is sometimes necessary to press the momentary contact switch two or three times before the signal actually operates. Even though in many instances the mechanism was heard to whirr, the arm did not actually move. This problem seems to occur when power is first switched on, at the beginning of a layout operating session. Or after power has been interupted for a minute or so. This implies a minor design fault in the mechanical actuation system.

      Further even if the system works as provided, it means you need to be in visual contact with the signal to ensure it has actually changed. Which is often not possible on larger layouts, if operators are not using some type of "walk about" controller.

      Yet further, as the current system of actuation requires that the two yellow wires are momentarily connected to "activate" operation. It is NOT possible to connect these two wires to a relay, in direct contravention of some of the instruction sheets found in certain of the signals I bought. Connecting the two yellow wires to a relay switch means that with a standard relay, its switch or switches are either constantly ON of OFF, and are NOT of the momentary type. So the signal would at best operate once when power is intitially applied. Do NOT therefore connect to a relay.

      As I wish my signals to operate from fixed operating positions many are out of sight of the operator. Further I need to connect my signals to relays which also interact with the position of points, other signals, and track circuits, as on a real railway. In other words my signals need to be fully interlocked. This requirement also ensures operators (and there are 8 operators needed for my exhibition layout), cannot "crash red lights" (pass signals at danger). As a section of track beyond each signal is also switched OFF automatically by the relays when the signal is at danger. So the current intermittant method of operating these signals is of little use.

      A fairly simple cure is needed, as follows:
      Having had no choice but to take the mechanisms to pieces, I can see that the current system is actually almost identical in operation to the Fulgurex motor driven point mechanisms I use. The only real difference between the point mechanism and the signal actuation mechanism is the type of micro switch used to switch off the mechanism at the extent of its travel in both directions.

      If the signals as currently manufactured were altered to the electrical method used on the Fulgurex point motor. This would require the current tiny switches to be changed, and would abolish much of the electronics currently on the PCB Board. A couple of Diodes would replace virtually all of the current electronics. This would allow the Black and Red wires to be connected via a DPDT (Double Pole Double throw NO centre off) type switch. Or too a suitably modified Dapol DCC "Signal actuation board", to operate the motor mechanics direct. It would also allow modellers like myself to alternatively connect the signal via a relay. As semaphore signals in real life HAD to be interlocked with other signals on the same track to ensure each signal was correctly "pulled off" in a strict order. i.e You cannot pull the Distant off until the Home AND Starter have first been pulled to the clear position !

      The LED could then be powered by another pair of wires, and this would allow the user to select a lower voltage for the LED if desired, as the LED's in my opinion are more like searchlights than semaphore signal oil lamps currently !

      Hope this helps.....

      The Duke 71000