The K-Line crossing gate saga

[thor]

Bob I thank you most sincerely for your time, trouble and patience!  Yes, my flashing LED's ARE rated at 5 volts so that circuit will work and forget trying to alternate them! I'll be grateful just to get them working anyhow.

I jumped the gun a bit - because these parts are so CHEAP - and also bought the Radio Shack Adjustable Voltage Regulator 276-1778. On the back of the card is a circuit diagram showing a pot of 5Kohms to adjust the center pin but the pot wont fit in the space I have so I guess this'll have to go in the parts box. I thought I could maybe experiment with different size resistors on that center pin to see if I can get it down to 3v. - its rated to put out 1.2 to 37volts, must come in useful some day.  Oooh its just occured to me this thing could be a useful controllable small power supply output.

I've got plenty to be getting on with now!  Thanks again - Mike.

 

[lionelsoni]

I just realized that you may be talking about an LED with a built-in flasher, perhaps something like this:

http://www.allelectronics.com/cgi-bin/item/LED-4/340200/RED_FLASHER_LED,_T-1_3_4_.html

This one is specified for 3 to 5 volts.  What information do you have about yours?  I would need to know just what you have in order to advise you whether or how you could use it at 5 volts.

If you are using a pair of these, it would be a problem to get them to alternate their flashes.  Or do you have something that already does the alternation?

[thor]

Hooray!  Thankyou Bob and here's your suggested component in a circuit to provide just what I need in conjunction with the dual flashing LED's I bought.

http://www.mrollins.com/pwrsp3.html

This is so cool! Much more fun and educational than just buying one.

PS:- Only thing is those LED's want 3 not 5 volts.  Um, is this a case of shoving in a suitable resistor? Or do I have to modify the circuit to get the output down?  I assume the IC 7805 is a Zener diode?

[lionelsoni]

Here is a 5-volt 1-ampere regulator from Radio Shack.  It goes downstream of the capacitor:

http://www.radioshack.com/product/index.jsp?productId=2062599&cp=&origkw=regulator&kw=regulator&parentPage=search

I believe that it will stand 35 volts in, which will allow it to work with a track voltage of as much as 25 volts.

[thor]

Thanks Bob. I ask questions but dont depend on answers! I usually keep searching but always hope that some expert will steer me right.  How I figured out the solution so far was to use one of those snap fastened 'Cirkit' by Elenco and basically "suck it and see" - the empirical solution.  Works for me, especially as these kits are idiot proof.

I still havent figured out how to make a variable power supply regulated but all helpful answers are gratefully received. I found out these links so far, the first 3 are British because I asked the search enquiry 'RailWAY (instead of ROAD) circuits'!

Hope these are of use to someone else:-

BRITISH

MODEL RAILWAY CROSSING

http://www.newrailwaymodellers.co.uk/railway_crossing.htm

 

MODEL ELETRONIC RAILWAY GROUP

http://www.merg.org.uk/links.htm

 

MODEL TRAIN CIRCUITS

http://www.hobbyprojects.com/M/Model_Train_Circuits.html

 

AMERICAN

MODEL RAILROAD ELECTRONIC CIRCUIT LISTS

http://www.mrollins.com/circuit.html

 

 

 

[lionelsoni]

The capacitor will filter the full-wave-rectified DC that you have now.  However, it will not regulate the voltage.  (There are numerous ways to do that.)

The capacitor should have a working-voltage rating of 1.4 multiplied by the greatest AC voltage (RMS) that you plan to put into the bridge rectifier.  The capacitance depends on the load.  You will get a peak-to-peak ripple voltage that equals the load current (in amperes) divided by the capacitance (in farads) and then divided by 120.  Ten or 20 percent ripple is probably fine for something like this.

Your Radio-Shack bridge rectifier was way too big for something like this.  A more suitable part would have been the 276-5512, which may be smaller than your built-up bridge:

http://www.radioshack.com/product/index.jsp?productId=2062581&cp=&origkw=bridge&kw=bridge&parentPage=search

[thor]

I ended up building my own with four fat diodes and it takes up less room than the SIL package did anyway AND it works!

I asked the following at OGR and my own website - its a cut and paste (hence the explanation of what most people know):-

By the time you reply I will have probably found the answer but what the heck...

I am trying to add two flashing LED's to a train triggered crossing gate. They work off 3volts and with two AA's and a 100 ohm resistor they are just the ticket!

Trouble is the track voltage could be anything from 3 to 18 volts and a resistor big enough to stop the LED's frying at 20v. wont let enough juice through to make them flash at lower power settings.

The crossing gate is brought into action by the approaching train acting as a single pole switch as it crosses an insulated section, which throws the solenoid that lowers the gate, the solenoid is powered from a track clip.

The obvious solution would be to make the LED's independent of track power but it would be more convenient to be able to use the same power feed. I built a bridge rectifier to get the AC to DC it fits nicely in the gate housing, now all I have to do is figure out how to take a variable input and get a steady output.

Would a capacitor do the job?  Could I build a circuit that used a capacitor to limit the output voltage, to take a variable input and provide a steady output?  I dont have any experience with capacitors so I dont know if thats the right way to solve the problem.

[lionelsoni]

Thor, your rectifier must be mislabeled.  The picture on the Radio-Shack website shows the pins to be + ~ ~ -

http://www.radioshack.com/product/index.jsp?productId=2062582&cp

[thor]

I spared you the full length line item description but it seems you did almost exactly what I have or, to be more accurate, your conclusions were the same though the fix is different!

I wanted to post the full page rant but I thought it would probably annoy more than instruct most people.

I am so used to having to re-engineer these toys that I now take it for granted it will be needed and judging by some of the awful rubbish I've seen, I will be having lots more fun because I actually enjoy problem solving.

My dad brought me up with the mindset "Look if I HAVE to do this, let it at least be done in such a way that I never ever have to do it again!"

[brianel027]

Thor, here's another item I could talk about:

The K-Line Crossing Gate, which has it's origin from the MARX version, has a tendency for the gate to not come up, or come up slugglishly after the train passes.

First, I took the gate arm off and primed and painted it white. Then I painted the raised sections of the gate, which were originally black, red with a brush. . Then I took a single 1/8 ounce lead tire weight, cut it in half and stuck those on each side of the bottom base of the gate piece. Then I brushed the end section black including the self-sticking tire weights.

I run my crossing gates off DC current. One is hooked up to an MTH scale track sensor which I run on DC current. MTH didn't have a clue whether this could be done but I now know it can. The second crossing gate is run off a 12volt 200ma DC power adaptor, which also operates my own created stationary layout mounted diesel horns.

Both gates work flawlessly now with the added weight at the end. Both gates also operate quitely on the DC current. I have also considered making the non-illiminated run gels somehow be lighted, but decided against it given the tight space inside the base solenoid assembly. I also worried that any additional wires might be cumbersome to my improved operation of the gate.

While I'm on K-Line accessories, the spring on the K-Line Barrel Loader accessory (the older one cloned from the MARX tooling) is subject to loosing tension. I have mucked around with these in the past and also made replacement springs, but that can be a time consuming task to get the spring to the exact right tension. What I have since discovered that a simple rubber band can make it work just fine. I also had a solenoid core burn out on one. I used the rubber band idea and made the Barrel Loader operater manually via a pice of fishline which you pull on and makes the Barrel Loader operate just fine.

For a cosmetic improvement, remove the building and all electrical components and repaint the entire structure. I made my base a redish brown and then put a safety stripe along the edge where the train pulls along side. The building was primed and then replaced on the structure with the windows facing the track instead of the opposite direction - which is the way it comes. I made the building illuminated using a plastic milk container for the window glazing... a cheap perfect solution for window material.

I also added a spot light on the platform to illuminate the action and created a walk way assembly to go alongside the acutal barrel ramp.

[thor]

I bought a K-Line crossing gate, just an arm that comes down as the train passes and ended up having to completely strip it and rebuild it because of numerous faults in its design and manufacture.

So I figured, having had to rewire the coil, completely re-engineer the horrible fulcrum/pivot and mickey mouse counterweight arm, I might as well put flashing red LED's behind the two plastic lenses.

To get the crossing gate with flashing LED's,  I went out and bought a 4amp 400volt bridge rectifier to attach to the track voltage and give me the DC I need for the diodes. Its a Radio Shack 276-1173 SIL package GBLO4 0408 with pinouts reading from the notched end (nothing) + AC - So I connected the track power to the unmarked (nothing) pin on the left and the AC one expecting DC at the + and - and got the short protection cutout, no way there's a short, I checked it all very carefully. I know some controllers can be a bit funny, mines NOT the CW80 its the previous gray plastic Lionel controller that comes with train sets and connects to a power brick. I just wonder if there's something weird going on that is a well known bug with these controllers?   No, its not the controller, I just tried powering it with the brick and got a big fat short!  So either the rectifier is faulty or its markings are wrong.  I used a heatsink when I connected up the pins so its not heat damage, I guess its just bad luck!  Funny thing, I never used a packaged rectifier before, I always built my own from discrete diodes and I've NEVER had a diode fail before.