You can get yellow with a red/green LED, but it is kind of orangy.
I actually do this with the eyes in the skull on the Low Rider engine mounted where the headlight was. (The headlight was “Frenched” into the front boiler door.) When the train moves forward both the red and green come on for a firely orange. In reverse, just the red comes on.
Yea, without blue, red and green make orange. You need to also have blue to end up with white.
'Scuse me. I flunked Primary Colors in elementary school. Of course you are right - it doesn’t make blue.
Daktah John, well there is a difference in additive colours and subtractive colours when we talk about primary colours. That confuses some people. With light, red, green and blue make white. With dyes/paints/pigments cyan, magenta and yellow make black.
So yous scused.
OK guys, I pulled my control panel from outside, To do so I had to disconnect all of the out going air lines to the switches. Not wanting to leave the panel out side all the time, I built a disconnect block for the air lines. This allowed me to bring the control panel into the workbench.
Well SUPPRESSES awaited me.
I hooked up the power supply ( Radio Shack 12VDC power supply)
Previously I had metered this at 13.9 VDC. Now I know that car batteries Volt out at 13.5 or such, so I wasn’t to surprised for this on a 12VDC supply. I hooked it all up on the bench, and today I metered 14.75 VDC. I’m not and electric genius, but when I turned on some solenoids and the reading went to 15.4VDC, I was puzzled at the increased voltage. Is this + voltage the power supplies way of regulating? I then measured the amp draw, and read .06 for one solenoid and .11 for two. With all on it read 1.3 amps, well within the rated draw. But with all on it read 14.5 VDC. Is this fluctuation in voltage Normal? And with as much as 2+ V sway, How do I regulate it?
Here is my control box guts, this power supply runs all of the controls, and was what I was going to use to power the LEDs also.
Am I asking to much for this supply? Or do I need to spend more $ on a separate supply for the LEDs? The Voltage range is well within the solenoids range of 10.8 to 18Vdc.
Use the CL2 instead of resistors and the power supply voltage will not matter.
If a LED is rated for 20 ma max then I would not go over this spec as it can shorten the life of the product. You can get away with over current but it only takes one to go bad at the wrong time (open house/demo).
As you suggest, the regulated voltage is higher than one would expect.
If you are sure that your volt meter is accurate, and that the power supply works to reliabily power all of the solonoids (try it for a while/extended periods), just size the resistors accordingly.
Just use 15, rather than 12 volts as your basis. A 620 ohm resistor puts you at just under 21 milliamps. You probably won’t even notice the small difference in brightness between the top and bottom of the voltage range.
David Maynard said:
Daktah John, well there is a difference in additive colours and subtractive colours when we talk about primary colours. That confuses some people. With light, red, green and blue make white. With dyes/paints/pigments cyan, magenta and yellow make black.
So yous scused.
Sorry David,
But those pigments make mud, not black. As we know black is the absence of color. Back in college, I dabbled.
You are correct that there are two color wheels; one for light and the other for pigments.
John, if the pigments are true and pure you can get real close to black, but as you said, its not pure black. I have seen dark blue, dark brown (mud) and dark purple on the copiers I work on, when they print out what we call “process black”. That is, black made with the 3 colours, Magenta, Cyan and Yellow.
Artist Acrylics stay muddy.
Ink is another realm to me.
John
Back on Topic… IT WORKS !! I went to the internet and ordered more then I needed, As this electronic stuff is my weakest link in life skills. I am setting out to improve my skills, So I bought a DC Power supply, a breadboard ( its much smaller then the pictures lead you to believe) with itty bitty little jumpers, Mouser supplied me with a bunch of CL2’s and a bag full of diodes, China shipped a gazillion resistors in about every conceivable size ( 7.5 ohm to a whooping 4,700,000 ohm ) and 100 bi-color red green LEDs for $3.99 including shipping.
Followed my own schematic and it worked. Well not the first time. BTW a 2VDC LED will light with 15 volts applied… It just doesn’t light for very long, well actually about 1/10,000 of a second, but it did light. Lesson learned… Double check what little hole you put that itty bitty jumper wire in. Poof, its dead… Lesson Two, CL2’s work only with power going the right way, DUH… I fried two complete LEDs and the Green side of another one.
Note switch position: The air solenoid kicked in, and the two lights lit opposite to each other.
And throw the switch and whaaa Aha…
Now this is my very first ever bread board rig up… I know its pretty simple, but I got it to work right.
Now I think that I will need to build a circuit board to mount all the diodes on and the CL2s to keep them out of trouble in the control panel.
And is the red brighter? It looks to be. (http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-cool.gif)
Yup… Just like you said that it would be, But not as bad as I thought. The LEDs are frosted with a wider viewing angle, and actually its the red ones that I wanted to be most noted, as that indicated that that line is blocked. This is a cell phone pic, so no real control of the settings.
OK my newbe ignorance, If I was wanting to “Balance” the intensity I would have to restrict the current to the red side by adding a resistor, thereby making it not so bright, Or, increase the current to the Green side, making it burn brighter, but greatly reducing it’s lifespan. OR both? If I put a resistor in series to the red side to decrease the current and it matches the green side, If my voltage changes, then all bets are off as to the “Balance”, or with the CL2 controlling the input, would the resistor in series on the red leg of the LED just help control the red side, and have no effect on the green side?
To reduce the current with the CL2, what you need to do is bypass current around the led, therefore you need to add a resistor in parallel to the LED to effectively reduce the current to the LED.
Dan, Again my learning curve needs a diagram. I’m not sure that I will change from where I am, which is the second schematic. But I want to learn and understand, so that I can if I change my mind. A simple sketch on a napkin will work.
And I think that there are several other non-electronic types trying to following along too.
Thanks for the learning help.
Dave Taylor said:
Yup… Just like you said that it would be, But not as bad as I thought. The LEDs are frosted with a wider viewing angle, and actually its the red ones that I wanted to be most noted, as that indicated that that line is blocked. This is a cell phone pic, so no real control of the settings.
OK my newbe ignorance, If I was wanting to “Balance” the intensity I would have to restrict the current to the red side by adding a resistor, thereby making it not so bright, Or, increase the current to the Green side, making it burn brighter, but greatly reducing it’s lifespan. OR both? If I put a resistor in series to the red side to decrease the current and it matches the green side, If my voltage changes, then all bets are off as to the “Balance”, or with the CL2 controlling the input, would the resistor in series on the red leg of the LED just help control the red side, and have no effect on the green side?
I don’t think that you would be able to simply add an additional resistor on the red side because the current limiter would try to compensate for this and allow more current to flow when the red is on. But you can try it in series and/or parallel. Worst that can happen is you fry more parts.
If you end up using two “devices,” they may as well just be the resistors, which as I noted are cheaper and you don’t need to think about polarity (as you found out).
You know how to do the calculations and have the pieces to try various combinations. Just shoot for 20 - 22 milliamps on the green and 20-30% less on the red and see how that looks to your eye. A 10% current overage will have little impact on the LEDs life.
Also, recognize that the “go to” resistor for train engine headlights is 1,000 ohms @ 1/4 watt. If the engine runs up to 24 volts, that’s 22 milliamps. Also, at 24 volts, that’s ~1/2 watt. If the train runs at 12 volts, that’s 10 milliamps, but you can still see the headlight in daylight.
To have current bypass the LED, you would need to connect one leg of a resistor to one leg of the LED, and the other leg of the resistor to the other leg of the LED. If you have 2 volts on the LED, and 20 miliamps, and you want to drop it 10%, then you would want 2 miliamps flowing through the resistor. 2 volts divided by 2 miliampes is 1000 ohms. Of course when you start shunting some current past the LED, the voltage would most likely change a bit. So I would start with 1000 ohms in parallel with the LED, like I said in the beginning of my post. If the red LED gets too dim, then use a higher value resistor, if you want it dimmer, then use a lower value.
If I had a cheap “regulated” 12v supply that metered at 13.9 I would throw it away. If later the same supply now read 14.5 volts, I would not throw it away, but smash it flat with a sledge hammer so no one else could use it.
Seriously, after all the $$ you spent on the air solenoids, you have a cheap supply (and it is malfunctioning?) ??
Greg
Greg, I see your point, but then again if its working why “fix” it? Besides, even with a regulator, doesn’t the output go up a bit without a load on it? Yes, 14.5 sounds excessive.
OK guys… I’ve had my doubts about the power supply from the start. I went up to Mouser, searched for 12Vdc 3amp power supplies, and I’m not sure what I need, Switched or regulated and what is the fundamental differences? Would a “super” wall wort work?
