Proximity switch

Discussion in 'Motorhome Chat' started by mikekaren2, Jan 23, 2014.

  1. mikekaren2

    mikekaren2 Funster

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    Hi, has anyone attempted to swap the Hymer "step out" warning contact switch with a proximity switch?If so any tips or advice would be welcome.


    Mike
     
  2. andyman

    andyman Read Only Funster

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    A proximity switch on it own will not switch 12v so an additional control will be needed. The control will also need to be dead both when the step is open and closed to prevent it draining the battery. Considering how often the standard switch gives trouble i would fit a new switch. In 5 years i have only had one switch fault.
     
  3. tonyidle

    tonyidle Funster

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    This would do the job nicely.

    http://www.ebay.co.uk/itm/PR18-8DP-...al_Components_Supplies_ET&hash=item43bbe388e0

    A 2.2W warning bulb is approaching the current limit of the switch so an LED warning light would be the best option. Although there will a constant current drawn by the operating circuitry inside the switch it will be measured in microamps & can be disregarded in terms of leisure battery use (it will be very much less than the battery's own self-discharge current).
     
  4. hilldweller

    hilldweller Funster Life Member

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    Good point. One I overlooked a few days ago when I suggested using one.

    One proximity sensor that takes no current is the magnet reed switch. Totally sealed. But it has current problems, depends on just what the load is on the step sensor circuit.

    Anyone seen a step circuit ?
     
  5. tonyidle

    tonyidle Funster

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    I have a circuit for mine - Omnistep I think - on a Hymer.
     
  6. JeanLuc

    JeanLuc Funster

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  7. Serendipitous

    Serendipitous Funster

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    If using a proximity switch which is permanently powered and the constant drain is an issue, one way around the drain issue would be to use a one shot timer that cuts off the supply to the sensor when the step is not required to travel. Wired so that when the step is required to extend/retract the timer is energised and runs for a number of seconds to confirm the step has been correctly positioned.

    Downside are systems which use the position switch to check that the step hasn't crept out during travel etc and then raise an alarm because there is no position signal.

    As mentioned by Hilldweller a reed switch and magnet make a good no contact switch with no moving parts.
     
  8. hilldweller

    hilldweller Funster Life Member

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    It could be done by a proxy sensor but the logic is the wrong way round to fit the sensor at the back. It would need to sense a hole, in other words as long as the step is out it sees metal, when step back it sees nothing. Then it would just replace the micro.

    There may be some inverted output sensors out there but might be pricey.

    Or a cheap little relay to invert the sensor output.

    Since the sensor would be powered from the fridge relay the drain would not matter.
     
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