Help me set up a Proximity,Timed Relay Circuit.

[Anonymous]

My Project: To Run a Trolley, Stop at a Station, Pause (an adjustable time would be nice), then restart......go arount the layout and when at the station again, Stop, Pause then restart.

How to do it ?????? For starters I have a Proximity ( Magnetic Reed) Switch, and a small magnet. The Reed Switch can be located in between any 2 rails, the Magnet can be secured to the underside of a Trolley. This is easy so far.

When the Magnet under the Trolley comes close to the Reed Switch, the magnet will open the circuit. I know this can shut off power to the track.....but I need expert help for the rest of the Relay and or Timing Circuit.

Appreciate any help with this design.......if of course you understand what I tried to describe above.

Thanks in advance......George.

[Anonymous]

George:

I can' t help you design circuits, but what you want is something like this:

1. Reed switch cuts power to track & causes a TIMER circuit to start timing down. These typically use a 555 timer IC, a capacitor & a variable resistor. The resistor controls how long it takes the 555 to time out.

2. When the 555 times out, you restore power to the track.

Essentially, the reed switch throws a DPDT relay one way. When the 555 times out, it throws the DPDT the other way.

Sorry I can't give you any schematics. I understand that you can buy ready made timers that essentially do what you want. There's another thread on here that talks about 555 timer circuits; do a search on "555" and see what you find.

Tony

[Roger Bielen]

Try checking the ads in CTT for the electronics firms, i.e. TAS, Burns, et al. What your trying may already exist.

Good luck.

[Anonymous]

Lionel has/had a low tech solution that was part of a passenger station, but may have also been sold seperately. The station I am thinking of was 132 Passenger Station. Apparently 115 City Station and 253 Block Signal. IIRC, they have an adjustable delay, based on a bi-metallic switch. I do not know if the units were ever officialy sold seperately from the items listed above, but you might try some of the big lionel parts supply people.

In doing a quick search for the offical names of the items listed above, I also stumbled across http://www.depotronics.com/products/micro1/ who seem to have microprocessor variants of what you are looking for.

[SPFan]

If you go to http:// www.national.com and type LM555 in the search window you can download data sheets that have wiring diagrams for timing circuits. You need to get a solid state relay (SSR) to interupt power to the track. You could do it with a mechanical relay if its sensitive enough or use a power transistor between the 555 and the relay. With a SSR no transistor would be needed.
Pete

[Anonymous]

Don' t you have to be careful with voltages & currents when you use a solid state relay? I'd imagine you could easily blow one out if you're not careful. In fact, didn't the Lionel SC-1 switch controller use SSRs? I remember reading that there were a lot of problems with these things burning out, so they brought out the SC-2, which uses mechanical relays, to fix the problem.

Tony

[SPFan]

The relays I would use for this are rated for 3-32 volts DC on the "coil" side and 18-330 Volts AC on the drive side at 10-25 amps depending on model. I have used them to start 1 HP motors driven by 5 volt logic gates. They are made by a number of companies including Crydom, Teledyne, Opto 22, and Continental Industries. I am fortunate to live near a electronic surplus store that sells them for a few bucks each.
That said the 555 timers can sink or source 100 milliamps which should be enough to drive many mechanical relays.
Pete

[lionelsoni]

You might be able to use the kind of thermal relay that is normally used for controlling electric furnaces. They can be found at any HVAC distributor. They are intended to be operated by 24 volts AC and can switch much heavier loads than you need. The price should be about $10. If it turns out that you can't operate one on your available accessory voltage, you can get a small 24 volt control transformer from the same place for a few bucks more.

I would forget about the reed switch and power the thermal relay through a track circuit, that is, using an isolated section of one of the running rails. The center rail of the same section would be powered through the thermal relay's contact.

The theory of operation is that the trolley car stops when it comes to that unpowered section. But its wheels complete the circuit to energize the relay, which, after a delay, closes the circuit to connect the isolated center rail to the rest of the track, starting the car up again. When the car leaves, the relay begins to cool down, to be ready for the next arrival of the car.

If the loop is too short, the relay might not reset in time. Eventually, it will of course. This might actually produce a more interesting operation in which the car does not stop every time.

[lionelsoni]

After thinking about it, I have a much better, simpler idea--if you are willing to run two trolley cars instead of just one.

Leave the center rail intact all around the loop. Isolate the running rails at the station from the loop, but not from each other. (This does not require any special track.) A trolley car that comes to this section will of course stop.

Isolate one of the running rails in a section or two on the approach side of the station. Connect that isolated running rail to the isolated running rails at the station. When a trolley car approaching the station reaches this section, its wheels will complete the circuit for the trolley car stopped at the station, which will depart. The approaching trolley car will then take its place, stopping at the station.

The approach section can be some distance from the station or immediately adjacent to the stopping place. If the latter, you will not even need to use any wire to connect it up, since it can connect directly through a track pin.

[lionelsoni]

A further refinement: Put a resistor between the approach isolated rail and the station isolated rail, so that the departing trolley car starts more gradually. The resistance value will depend very much on your trolley cars, the transformer voltage, and how fast you want to run; but I would start with about 10 ohms at 10 watts.

[Anonymous]

Bob Nelson:

Brilliant ideas controlling blocks by using the outer rails.....why didn't I think of it.

In fact my Lionel Booklet from 1956 "How to Operate Trains and Accessories"
.....has similar suggestions for controlling two trains, I should go back to those
pages, they have real basic ideas.
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Thanks, George Warrin

[lionelsoni]

My pleasure. Let us know what you do and how it works out.