2 years in the making and now I have hit a major problem. I am trying to connect the saucer section lighting with the secondary hull lighting. but i cannot get everything to work. I have a flasher/strobe board in the Saucer (made by Jwrjr) and that works fine in the saucer...but when connected to the secondary hull the strobes and flashers don't light....it gets worse. The secondary hull gets HOT and the wall wort gets SUPER HOT. The wall wort is 12V 1.2A. And to make matters even worse all of the steady on lights are now flashing (they were when the whole set up was super hot, etc...).
What is going wrong? Do I have a short? Do I not have enough juice? Am I just screwed...and in that case in need of a rubber room?
Info that is missing:
Saucer lighting power supply? You said it was working, how was it powered when it was working?:
1)Directly off the wall wart,
2)off a battery pack,
3)through the connection to the secondary hull prior to fitting it together (maybe with an extension wire).
If the last option is how you have been doing the pre-assembly powered testing then it is:
I. a pinch short that has occurred when trying to snap the saucer into the secondary,
II. a polarity swap, where you re attached the saucer wiring backwards.
If option 2) is how you have been testing then my bet is you have a power supply mismatch and/or a wiring mismatch.
If option 1) is how you have been testing, it is a wiring mismatch in what the secondary hull is suppling to the primary saucer.
Once again what we need to know is:
What connections is the saucer have/need: power supply and LED drives
What connections are coming out of the secondary hull: power supply and LED drives.
It sounds like the primary saucer's blinking output is being used to drive the secondary hull, probably not what is suppose to be happening, this means that the secondary hull is expecting power to come from the saucer, the saucer is suppling it from the strobe drive.[/code]
After trying to trace back according to your questions I think I found the short and solved most of the problems. Hovever I am still having some what of a heat issue from the secondary hull and AC adaptor.
My initial guess is that the power suppply (wall wort/AC adaptor) is insufficient. I switched to a new adaptor and I am still getting the heat issues.
The current power supply (the one I used to get everything working) says on the back:
Switching Power Supply
Model:DSA - 0151A - 12 S
Input: AC100 - 120V 50/60Hz 0.4A 40VA
Output: DC + 12V/1.25A
Do you think the amperage is too small and that may be causing the heat issues. Or do you think it is because the power supply is unregulated?
If the power supply was over heating then it might not have enough power, if the secondary hull is over heating there's something amiss in the wiring or in the power calculations.
One thing that I see happening with folks wiring up a lot of white LEDs, is they use a single resistor to drop the extra voltage from the power supply. Sometimes referred to as a current limiting resistor.
The danger or problem with this is that the resistor is eating extra power. Extra power is always lost as some other form of energy, in this case heat.
The other danger is that the wattage of the resistor needs to be calculated as the sum of all the currents that trace out form it. As one would expect, the resistor is passing the current out to multiple LEDs, each LED takes a part of the whole. That whole must pass entirely through the resistor. This is one of the reasons not to use one resistor to drop the power supply voltage to say a 3.3 volt power supply for white LEDs. The resistor will just be burning off the extra voltage (* sum current for all LEDs).
Can you tell me how the wiring is setup?
All whites on a daisy chain (plus to minus to plus to minus) so that the/each chain wants 12 volts or
In parallel, plus' tied together, and grounds tied together, then feed to a resistor to drop the correct power (voltage of power supply/ total number of LEDs' current).
Then what is passed to the secondary? 12 volts direct or is it taped into the lower LED chain some how?
On a side note...NEVER trust the output voltage of ANY power supply, ESPECIALLY wall warts!!! Always check their output voltage with a VOM or DMM before plugging in to your circuit!
Otherwise, like Sparky said, sounds like a resistor wattage issue. With resistors, it's better to have a big honkin' 5 watt resistor than a 1/4 or 1/2 watt, especially when using them in big LED lighting applications (and 5 watts might not be enough).
Scottie
I am fearful when I see people substituting fear for reason
Sparky,
To answer your question each LED has its own resistor. I havn't tested the voltage output of the A/C adaptor but I am leaning towards this being the problem. Because I can't bring myself to cracking open a completly painted and detailed secondary hull to search for a short ( I hope there isn't one).
What do you think?
Thanks again for all the help.
And thanks to everyone else for the help. i'll eventually get this build done right
Scott
SDHLaw1701 wrote: I havn't tested the voltage output of the A/C adaptor but I am leaning towards this being the problem.
The amp rating on your power supply is too low ( Output: DC + 12V/1.25A).
Research a dedicated supply of 12 volts / 5 amps at: http://www.astec.com Model LPS53
What are the values of the resistors on your LEDs?
If it is over heating putting more power into will likely lead to total melt down and fire.
since each LED has its own resistor, then there wouldn't be any extra heat generated by the addition of the saucer.
The power through each LED/resistor loop should be whatever you setup the loop to have. Given a constant and accurate power supply.
Now that said, it could explain why the wall wart over heats when it tries to power both the secondary hull and saucer. If that's all that is over heating my bet is that you're power supply is to small.
To calculated total current needed, take the sum of all the loops. each LED resistor combo needs the current you used when calculating the resistor (20 mA maybe?) These are additive so 5 loops need a total of 0.10 mA.
Now you need to figure out what the flasher circuit needs. The LEDs it flashes, plus some amount of current for the chip. You can look up the specs on the chip it will give you worst case current draw. If the circuit direct drives the LED then that includes the LED's current so you don't need to add it again. IF the circuit uses a transistor to drive the Flashing LEDs then their current isn't included.
To help simplify this can you give me a break down of what is where and how it is wired?
What I know now:
1) Secondary hull LEDs are wired with their own resistors, and therefore should be tied to a common 12 volt line/buss.
2) saucer section expects 12 volts from the secondary hull?
3) saucer flasher unit set to run off 12 volts?
a) LEDs are transistor driven?
b) LEDs are direct drive?
The flasher circuit itself only draws a few ma, maybe 10. The way this works is that you connect the resistor/led pair to the positive supply on the positive side and the flasher on the negative side. In effect is is a switch between the led/resistor and ground. The flasher and strobe outputs are each rated at 250ma max. As long as you don't draw more than 250ma total for each of the 2 outputs, I don't care how many leds you divide that up between.
1) Secondary hull LEDs are wired with their own resistors, and therefore should be tied to a common 12 volt line/buss.
2) saucer section expects 12 volts from the secondary hull?
3) saucer flasher unit set to run off 12 volts @ 10 MA
b) LEDs are direct drive current: Sum of Strobing LED Currents (if different current were used for reds, whites, greens, high intensity LED, etc.
Are there any other special effects, did you use cold cathodes in the nacelles? those draw a lot of current compared to LEDs.
If there is heat in the model itself, then there are resistor issues. Resistor values on this particular build were never disclosed. The total number of LEDs were never disclosed either.
If it's just the wal-wort heating up, then it's being overdriven.
I've had great success with the power supplies I've used (as per previous post) and the proper resistor combinations on each LED. An Excel Spreadsheet, provided to me by an electrical engineer (since I am not), specifically calculates all resistor values predicated upon predetermined Ma's and dictates not only the minimum resistor value but the minimum allowable power supply to be used. That's why I recommended the 12v/ 5 amp supply. But then again, that's what I do so I'll just stay out of this and keep to myself.
I agree with the the idea of using a real regulated power supply. In theroy you can get at 10 or 20 amp power supply, the circuit will only draw the power it needs. But if wiring gets shorted or something burns out as a short circuit (unlikely but it can happen). Then the power supply will have the power to put enough juice into the model to make it into a heater element like on the stove.
In this case we need to figure out what's wrong in the secondary, the power supply's limited current is probably whats protecting it from burning up.
The space station the group built some time ago uses my 12 volt 10 amp supply, that is normally used to power my ham radios. It's not the greatest power supply as it takes a while to come up to full voltage. There's a lot of lights in there and mixed devices (motor, fluorescent tubes, and LEDs).
Sparky wrote:I agree with the the idea of using a real regulated power supply. In theroy you can get at 10 or 20 amp power supply, the circuit will only draw the power it needs. But if wiring gets shorted or something burns out as a short circuit (unlikely but it can happen). Then the power supply will have the power to put enough juice into the model to make it into a heater element like on the stove.
In this case we need to figure out what's wrong in the secondary, the power supply's limited current is probably whats protecting it from burning up.
The space station the group built some time ago uses my 12 volt 10 amp supply, that is normally used to power my ham radios. It's not the greatest power supply as it takes a while to come up to full voltage. There's a lot of lights in there and mixed devices (motor, fluorescent tubes, and LEDs).
Hey Sparky, is it just a regular supply or something more sophisticated. My biggest problem in building high current supplies is finding a transformer with the current capacity that doesn't weigh 30 pounds and cost more than an arm and a leg!
Scottie
I am fearful when I see people substituting fear for reason
Its not a homebrew. It has some weight as it's based on transformer and cap system. You can see the back of it in this photo, the big regulator transistors are visible. . . http://www.kc6sye.com/images/images_05_ ... _metor.jpg
Thanks for all the help so far. I am sorry it has taken me so long to reply but I had to be away on business for a while. Before I left I did discover a short on the secondary hull. That corrected the lighing issue but it did not solve the heat issue. I think I am going to try a regulated 12V/5A power supply. The resistors are all 512ohm and the leds are too many to count but I figure currently there are approx 60. Do you all think the larger power supply will solve my problem?
Thanks again for all the help and happy new year to all.
Scott
So you have a 512 ohm resistor on each LED, that's good it means the LEDs are running on about 2 volts well under the 3.3 volt limit for whites and blues.
At 20 mAmps an LED your 1.25 Amp power supply can run 62 LEDs, this assumes there are no other circuits in there, blinkers etc. Those take their own power and you have to calculate their current draw based on the most they might draw at any given time (peek) other wise the power supply won't have the power to supply it.
I wouldn't throw a fatter power supply on there, if the Secondary hull is getting hot, a bigger power supply will dump more power which = more heat. Eventually whatever is getting over powered in there will burn out or melt down.
Ok, still having major heat issues in the neck and secondary hull. I got a regulated powersupply putting out 12v 4A. I've been doing a light test and have had the refit all powered up for the last 40 min and I am reading a peak temp in areas of the neck and secondary hull of 124 deg. F. (using an IR thermometer, with a room temp reading of 82 deg. F.). What the heck is going on? As stated before each led has its own 512 ohm resistor. I have Jwrjr's nav board and torpedo board connected as well. The saucer seems pretty cool (with the occasional hot spot, but nothing quite as hot as the neck and secondary hull). I am almost compleated with this beast and now it seems that I might have to crack her open to see what is the problem. Any help, imput or ideas would be greatly appreciated. Thanks
Scott
Something is getting shorted out, at this point the only way to know is to open it up and inspect each wire and solder point. Look for pinches that have opened up insulation or pushed together exposed solder joints and or leads.
Just a thought could the flasher/strobe board be part of the problem? The reason I ask is that all the lights tahat are supposed to flash/strobe work but, three strobes (the two white lights top and bottom at the front center of the saucer and the white light on the top of the bridge module) flash but do not go dark. Meaning all the other flasher/strobe lights flash on/off these three lights flash but are always on. Does this make any sense?
Thanks
Scott
Yes it sound's like a set of the LEDs that are supposed to be strobing are getting a direct feed from another power source, or are plain mis wired.
If they were shorted to a direct feed, I would expect that all the Lights on the strobe would be on all the time, but if the board has a separate feed for that string, then the other strobing lines would be isolated.
I was testing some circuits sometime ago and even with a voltage regulator powering a few other circuits, it did get slightly hot. So, I think there is a short somewhere, maybe some wires are squashed together.
Anyway, in this video, I was describing about the 1701A's Navigation and strobe light timing based on a single PIC chip. This is a prototype circuit as I have not left it running overnight. But this was more than a month ago.
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