Firefly Magic LED AC/DC Adapter Problem

GhostLighter

GhostLighter

Member
Hey everyone,

I am at a total loss on a problem I'm having. We have purchased some imitation fireflies for a show we're going into tech for soon. The product is Firefly Magic FMS-07. They are meant to be run off of (2) AA Alkaline batteries, but I need them to run off of a dimmer (for obvious reasons). So, I bought a 3V 1.5A AC/DC adapter to replace the batteries. However, the microprocessors that control the random quick on-flicker off effect don't seem to like the adapters. When directly hooked up, all 7 LEDs come on with a steady flicker, instead of the one-at-a-time random on-flicker off. Now this is where it gets interesting...With some very precise adjustment to how far the male barrel connector goes into the female barrel connector, and with some adjustment to the angle, the LEDs work as they should. But even a millimeter of movement from the "sweet spot" will cause all of the LEDs to revert back to the steady flicker. I've tried replacing the barrel connectors with Molex connectors, to insure a good contact, but no change.

ANY advice/guidance would be appreciated. I haven't been this stumped in a very long time...
 
Do you have the AC/DC adapter plugged into a dimmer?

If so that is most likely what is causing the unit to malfunction. Dimmers send out a modified sine wave which anything that is not an incandescent load won't like and will potentially damage the unit. Things like LEDs, movers, dimmers, computers, projectors should NOT be plugged into dimmers EVEN if they are parked at 100%.

It is strange that it was working when you jiggled the barrel adapter. It could just be luck.....
 
All of this testing has been done on straight-from-the-wall 120V power.
 
The product web site indicates that it uses NiCd batteries normally (recharged through the PV cells) and you can test it with regular alkalines. When you test with alkalines they come on and go off. Since alkalines are typically 1.5v whereas NiCd are ~1.2v, perhaps the circuitry doesn't like the extra voltage? Do you have an adjustable supply or can you put a set of power resistors in series (voltage divider) to reduce the voltage a bit and see what happens?
 
GhostLighter said:
All of this testing has been done on straight-from-the-wall 120V power.
Click to expand...
The AC/DC Adapter might be very oversize ( "2 - AA standard Alkaline batteries for indoor use, and will last for up to 12 weeks of continuous 'Firefly' flashing, flickering, and fading" http://www.fireflymagic.com/fireflies/FMS-07.htm -> AA Alkaline batteries about 2600 mAh --> 2.6Ah/(24hours is day*7 days a week*10weeks ) = < 0.02 Amp Avg at 3V), AC/DC Adapter might be making 4+ Volts at no load (Or very little load) with lots of ripple. What is the DC voltage of the Adapter with no load?
 
Between 3.0 and 3.2 VDC with no load. 3.2 VDC with the firefly load. With the load, it holds very steady.
 
VCTMike said:
The product web site indicates that it uses NiCd batteries normally (recharged through the PV cells) and you can test it with regular alkalines. When you test with alkalines they come on and go off. Since alkalines are typically 1.5v whereas NiCd are ~1.2v, perhaps the circuitry doesn't like the extra voltage? Do you have an adjustable supply or can you put a set of power resistors in series (voltage divider) to reduce the voltage a bit and see what happens?
Click to expand...

They seem to run perfectly fine with the two alkalines. And when metered with the alkalines, it's 3.3 VDC. And with the NiCd's, it's around 2.7 VDC. So the microprocessors seem to be okay with the difference between the two battery types. But they say, "Nah nah, no no" to the AC/DC adapter.
 
GhostLighter said:
They seem to run perfectly fine with the two alkalines. And when metered with the alkalines, it's 3.3 VDC. And with the NiCd's, it's around 2.7 VDC. So the microprocessors seem to be okay with the difference between the two battery types. But they say, "Nah nah, no no" to the AC/DC adapter.
Click to expand...

Do you have a 'scope around to see if there is appreciable ripple on the DC or if it's some kind of high frequency chopped square wave from the wall wart? That seems to be the only thing that comes to mind that might be causing the effect you're experiencing.
 
I would contact them because they do have this 110v ac fireflies.

And maybe they can advise you on how to transform to the 110 version or send it back and get the indoor wall one.
 
I wish that were an option at this point. The department that placed the order was not aware of that model when they placed the order. My only option now is to find a way to either make them work with the adapters or run all of the different strings to a central battery box and have it be crew-op'ed...
 
GhostLighter said:
I wish that were an option at this point. The department that placed the order was not aware of that model when they placed the order. My only option now is to find a way to either make them work with the adapters or run all of the different strings to a central battery box and have it be crew-op'ed...
Click to expand...

Will an inline electromechanical relay controlled by the dimmer work to switch the battery supply on/off? Depending on the dimmer's waveform it might be acceptable without any damage to the relay coil.
 
Is the 3 volt adapter really 3 volts? Meter it. Some possible work-arounds: If the adapter is running a bit high, put a diode in series with it (1N4004 or anything close would work), The diode will drop about 1/2 volt. Also, try slapping a 1000mfd 15 volt (or anything close or larger) electrolytic capacitor across the feed going into 3 volt feed going into the unit. That should kill any ripple.
 
JD said:
Is the 3 volt adapter really 3 volts? Meter it. Some possible work-arounds: If the adapter is running a bit high, put a diode in series with it (1N4004 or anything close would work), The diode will drop about 1/2 volt. Also, try slapping a 1000mfd 15 volt (or anything close or larger) electrolytic capacitor across the feed going into 3 volt feed going into the unit. That should kill any ripple.
Click to expand...

You were right on the money. The capacitor did the trick. Can't thank you enough!
 
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