Building a RR Crossing with my kid

Thread Starter

baileyby

Joined Sep 11, 2022
3
Hi! Like many boys my son is obsessed with trains and has asked if we could build a train gate together (aka train crossing) in his room. I'm handy, so the bulk of the project won't be a problem, but I'm not sure how to wire the lights. I was thinking of purchasing the two of the lights from Ali express below, and I'm assuming I could use some 12V DC converter from some old piece of electronics as a power source. However, I'm not sure how to make the two lights alternate back and forth. Most of the wiring diagrams I've seen seem to be for very small projects or individual LEDs, so I"m not sure if they'd work. I appreciate your thoughts and suggestions.

https://www.aliexpress.com/item/2251832623667312.html?spm=a2g0o.cart.0.0.230d38daD9qcIy&mp=1
 

sghioto

Joined Dec 31, 2017
3,409
Here's a 555 circuit with transistors to drive the LEDs. From the specs listed from your link I believe the current draw is 160ma for each LED.
VR1 is to adjust the flashing rate.
1662933800458.png
 
Last edited:

Ya’akov

Joined Jan 27, 2019
6,561
Welcome to AAC.

I think the easiest possible way would be to use an automotive flasher with a SPDT (Single Pole Double Throw) relay. The flasher is a specialized relay which (traditionally, and in most current cases) uses a bimetallic spring the is heated by a resistor when power is applied.

When the spring snaps over, it cuts off the power to the resistor as well as to the load, then it cools, and snaps back starting the cycle over. It only does one thing, blink, but if you wire that to a SPDT relay’s coil, and one light to the NO (Normally Open) contact, the other to NC (Normally Closed), with the 12V supply to the common terminal, they will alternate.

The downside of this arrangement is that you will have no control over the speed of the flashing, though it would probably be a reasonable one. It would make a satisfying clicking noise, which is a bonus in a case like this.
 

MisterBill2

Joined Jan 23, 2018
13,128
The scheme in post #2 could work, but I did see that the current was given as 160 mA. So transistor heating will be a problem with those 2N2222 transistors. I am guessing that this flasher gate will be on for extended periods of time.
 

Thread Starter

baileyby

Joined Sep 11, 2022
3
Wow, Im blown away at all the suggestions everyone, thank you. I will read your suggestions, make a call, and post the result once it's done!! THANK YOU!

P.S. Yes, this is supposed to be more near-life size as it will be floor-to-ceiling standing in his room.
 

Thread Starter

baileyby

Joined Sep 11, 2022
3
Hi! Like many boys my son is obsessed with trains and has asked if we could build a train gate together (aka train crossing) in his room. I'm handy, so the bulk of the project won't be a problem, but I'm not sure how to wire the lights. I was thinking of purchasing the two of the lights from Ali express below, and I'm assuming I could use some 12V DC converter from some old piece of electronics as a power source. However, I'm not sure how to make the two lights alternate back and forth. Most of the wiring diagrams I've seen seem to be for very small projects or individual LEDs, so I"m not sure if they'd work. I appreciate your thoughts and suggestions.

https://www.aliexpress.com/item/2251832623667312.html?spm=a2g0o.cart.0.0.230d38daD9qcIy&mp=1
I just wanted to say thanks to you all. Attached is our finished project, and my son absolutely loves it! We ended up going with the PCB006 circuit board on eBay 'cause it was cheap and simple. The first was a dud, but they sent me a second one and it works perfectly. Thank you so much for all of your great suggestions and helping us!

thumbnail-2.jpeg
 

Reloadron

Joined Jan 15, 2015
6,965
I just wanted to say thanks to you all. Attached is our finished project, and my son absolutely loves it! We ended up going with the PCB006 circuit board on eBay 'cause it was cheap and simple. The first was a dud, but they sent me a second one and it works perfectly. Thank you so much for all of your great suggestions and helping us!

View attachment 279552
Your last post makes everything in this forum worth it. :)

Ron
 
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