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Dale H
Topics: 30   Replies: 30
posted on Jan 21, 2015:

Block signaling normally is a function of train position not time. That circuiting is discussed here using relays.and the outside insulated rail method. It is more prototypical than the one being described here. Please copy and paste this link to view


However I was asked for a circuit which will give a timed yellow for a block signal with 3 LEDs, red,yellow and green. This can done easily with 2 SPDT relays,some diodes and 2 capacitors.

The diagram below shows a hookup for a PWZW. But can be used with most any transformer with an accessory tap.

The diode off the U of the transformer provides half waved rectification for the 3 LEDs. The half watt carbon resistor,1200 ohm or more protects the LEDs from over current. Larger values can be used to dim the LEDs if they are too bright. For block signals using light bulbs these could be omitted. Diodes across the relay coils are for spike suppression. The 2 diodes off the + of the bridge rectifier prevent the capacitors from sharing. 1n4001 or similar diodes are fine and cost a few cents each.

Note how the relay contacts are wired. In operation,if both relays are off,the LED is green.
If relay 1 is on and relay 2 is on or off the LED is red.
If relay 1 is off and relay 2 is on the yellow LED is lighted.
The B tap of the ZW is shown powering the relays and the LEDs but the C tap could also be used to power the LEDs separately.

The relay coil circuit is completed by the outside insulated rail method. (The train wheels complete the coil circuit whenever 2 or more pair of train wheels occupy the block) The relay coils can be 12 or 24VDC. For 12 volt DC relays the B tap would be set at 9 to 10 volts. For 24VDC coils the tap could be set at 18-20 VAC. I recommend 24VDC coils as they will not be accidentally burned out if the throttle is mistakenly pushed up too high. The 1 amp or more bridge rectifier provides rectification for the DC relay coils.

Capacitor 1 across relay 1 can be small 100 uf ,220 uf for example. The purpose of capacitor 1 is anti chatter and smoothing out the pulsed DC current to the DC relay coil. It charges the pulsed current to peak,voltage is increased by 41%.. So the 18 VAC becomes a perfect 24 VDC filtered with the bridge and capacitor. 10 VAC would become 14 VDC. So be careful if using 12 VDC relays. Attention should be paid to the polarity capacitors,as well as diode polarity. A backward diode will not conduct,or across the coil cause a short circuit. A backward capacitor will explode and make a smelly mess.

When the train wheels occupy the insulated rail section. both relays energize and stay that way until the train leaves the block and the capacitors discharge. But relay 2 will drop out after relay 1 if capacitor 2 is larger and stores more energy. Capacitor 2 across relay 2 coil now has the added function of being a timing capacitor. When charged it stores electrical energy and will hold open relay 2 when power is removed (when the train wheels leave the block) and result in the yellow LED staying lighted until the capacitor discharges,only then will the block signal will return to green. The amount of time depends on the characteristics of the relay coil (resistance in ohms) and the amount of capacitance. For a typical relay this is about 1 second per 1000 uf of capacitance. So a 4700 uf 35 volt one would give perhaps a 4 to 5 second yellow. For best results use relays with higher coil resistance,240 ohms or more. Avoid 12 volt automotive type with 88 ohm coils. Capacitors from 1000 to 10000 uf can be tried. 2, 4700 uf ones can be wired in parallel to get that value. High value capacitors,such as the ones used on relay coil 2 may induce some arcing on the outside train wheels when they first roll into the block and complete the circuit. This is due to the large inrush of current when the capacitor first charges. If this is a problem,simply install a half watt carbon 18 ohm,or 33 ohm or similar low value resistor in series with one of the leads to the capacitor. This is not shown in the drawing.

3 light block signal with timed yellow fo...
Topics: 31   Replies: 13
posted on Jan 14, 2015:

Here are some of the parts for the house.
The porch post have already been completed.

The siding and roofing are printed on paper.
The papers are sprayed with a matte clear to seal them, then they are cut to size and glued to the building with a spray adhesive.

The finished building.

O-scale house
Topics: 8   Replies: 14
posted on Jan 8, 2015:

Each year I put up a large community train display. This year I built three accessories that the kids could activate, but now I need more ideas!
The accessories must be able to work unattended- meaning it does not require someone to attend it. I had an airplane, that the propeller spins, a fire station with doors that went up & down, and a Spider man that would swing out from behind a building, then back behind it. I can't have log loaders that need reloaded, coal loaders that need unloaded, stuff like that. What are the ideas for some animations that would go well in the public display?
Layout Ideas
Topics: 8   Replies: 14
posted on Jan 8, 2015:

There is something about an idea. You have something that you think about at night, so you take that idea, research it and develop it into a real product. After a life long interest in The Andy Griffith Show reruns, it seemed to me that the Mayberry Courthouse would be a great building in O gauge. I couple buy the plastic pattern sheets for the brick, but I couldn't find anything close for the windows or doors. So I came up with a design, sent it to a gent that does laser engraving, and I am pretty pleased with the final result. This is my prototype. I can make additional kits if there is an interest.
1st Custom Building
Roy James
Topics: 1   Replies: 2
posted on Jan 1, 2015:

The video below filmed some time ago gives an introduction to my railway.
As time permits I will add further photographs and video's

Dream City Railway
Topics: 21   Replies: 20
posted on Dec 29, 2014:

Supervising the Final Loading
Topics: 1   Replies: 2
posted on Dec 14, 2014:

Does anyone have a schematic for an electronic whistle relay to replace the old Lionel 2.5 volt dc solenoid activated dc replay that opens and closes the ground to the whistle motor?
I purchased an electronic whistle relay from a train dealer and wondering when I get if anyone could draw a schematic from it so that I can build them for myself.
Because it is my under standing that Lionel no longer makes this relay as a separate item as it is now integrated in the entire electronic unit for the locomotive.
I would and need to make some for myself to replace the old pre and post war whistle relays in some tenders for myself and grand Kids for whistles like the 2671W and 2046w and many other whistle Tenders from that era.
Your help and feedback would be greatly appreciated!
electronic whistle relay to replace old L...

O Gauge General Categories:

Electronics & Wiring (52)
   Crossover protection
Tinplate (8)
LED Lighting (31)
   Cheap LED Tea Candles
Electronics & Wiring (52)
   electronic whistle relay to replace old Lionel relay
Trackside Structures & Accessories (86)
   Auto Repair Garage
LED Lighting (31)
   Constant brightness passenger car using 12V LED strip
Layout Remodels (4)
   layout update
Great Engine Facilities of O Gauge (23)
   MY transfer table
Great Bridges of O Gauge (58)
   TW Trainworx Bridge B54 with lights opinions
Trackside Structures & Accessories (86)
   custom cardstock buildings

O Gauge Member Blogs:

Dale H  (29) Zeke  (10)
jdcrawler  (22) RogerPete  (7)
DAVE UPTON  (5) Roy James  (1)
stan  (7) Richard E  (41)
jhainer01  (7) StanField  (4)
AG  (27) SE18  (3)

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