Hallo everyone,
I am knew in the forum. forgive my English, i will try to make u understand my problem.
I have the Faller 222170 level crossing with motor and i am trying to make it work automatically, when the train passes in front of the road. The manual says something of using a relay and some contacts but looking to the internet found out that it is very expensive. My question is: Could i use a reed switch with magnet to do it? What do i need the relay for? Can't i just connect the switch between the motor and the transformer? The diagram in the manual says that i have to use 6 contacts. What is the purpose of that. Can i use this kind of reed switch?
http://www.miniatronics.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=M&Product_Code=32-N58-05&Category_Code=3_1&Product_Count=0
Thank u in advance for your help
A reed switch is normally for VERY low current - switching the motor on and off directly will eventually cause the contacts to be damaged or maybe even fuse closed. That's why they recommend using a relay. Relays aren't terribly expensive, and in most cases you can use the same power supply to turn the relay on and off. I would also recommend a diode across the realy coil so the back-EMF from the relay won't arc across the reed switch contacts when the contacts open and the relay drops out. Hard to draw it with text. This wiki article shows it: http://en.wikipedia.org/wiki/Freewheeling_diode
The symbols labeled L and R is the relay coil. On the right is the switch, on the left is the power supply.
--Randy
Modeling the Reading Railroad in the 1950's
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