Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Electronic Projects => Topic started by: TerryD on September 23, 2013, 02:37:40 pm
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I just got a led light to read by at night. I really like it. Direct from Hong Kong. It takes 3 triple AAA batteries. It has an input for a transformer. I stuck a 9v transformer in there and immediately blew up the lights. How many volt transformer do I use? All triple AAA 1.5 volt batteries are facing the same way ..if that makes a difference.
If I get the correct answer, I will stop getting new ones of these. Their military machine takes the hit and slows down the eventual military take over by 3.8 seconds. Thats 3.8 seconds more of freedom for those of you under 50.
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On my abacus, 3*1.5V is 4.5V, not 9V.
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On my abacus, 3*1.5V is 4.5V, not 9V.
yes, and even on fingers it works out the same
Not sure why you plugged in a 9 volt adapter when you knew it was 3 x 1.5 volt batteries in series = 4.5 volts
That is why china will take over the world. :l2:
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I just wasn't thinking. It was a variable transformer that I just plugged in and thought I could dial in the right volts. Plus I actually did not know how many volts it would need AND I never experienced "problems" with "too many" volts.
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All batteries facing the same way ? In parallel ? If so, 1.5 volts. Measure.....weird...
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How could I actually tell if they are in series or parallel...since they are all facing the same way??
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How could I actually tell if they are in series or parallel...since they are all facing the same way??
"All facing the same way" kinda implies they are parallel but that certainly does not guarantee they are parallel. You need to look at the battery holder and determine if all three positive terminals connect together and all three negative terminals connect together. That would be a parallel connection. If you see that the positive terminal of one battery actually connects to the negative terminal of another battery, then you would have a series connection. Either way, you blew it up by putting too much voltage on it.
I have two different LED flashlights (one standard style, the other headband style). Both use three AAA batteries with totally different style battery holders. But it is obvious to see that the batteries are series connected for 4.5V in either flashlight.
I seriously doubt that your AAA batteries are connected in parallel because most LEDs require at least 1.7 to 2.5 volts to even illuminate.
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I seriously doubt that your AAA batteries are connected in parallel because most LEDs require at least 1.7 to 2.5 volts to even illuminate
yeah, that's why I assumed it was a 4.5 volt power supply
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> "All facing the same way" kinda implies they are parallel but...
Right, "but".
I think a little thought goes in these things. How hard is it to get four batts right-way in a flat 4-cell holder? A bit hard. How about my old digi-camera where you drop cells in wells? I get that wrong half the time. I think that with a cylindrical product, and no space for labels, the ONLY practical way is "all the same way".
Also with 4 cells, the ends of the series-string come out the same side of the holder. With three cells, there MUST be a jumper from one end to the other. Given such advanced technology, maybe it isn't that hard to do three jumpers to un-invert the middle cell.
Also white LEDs need about 3.5V to light at all. We need some resistance so current does not go to infinity. Low-cost LEDs have a little resistance. AAA-cells have a little more. I think they scale both factors so NO added resistance is needed *for 4.5V three-AAA power*. An external source must be appropriate voltage and resistance so the LED current does not go so high as to burn-out.
> I never experienced "problems" with "too many" volts.
You have a charmed life. Over-Voltage is one of my favorite ways to blow stuff up. Very memorable: 170VAC into a 115V mixer-amplifier.... FWOOMM!! I've over-volted lamps and tube heaters (yes, tube heaters are pretty tough, but 4X over-volt kills them in a minute). "40V" transistors in 60V amplifiers was another hobby (I was on salary so I replaced them as often as needed, happily). My last house, I noticed that lamp-life was very poor, and discovered 128V at the wall. Not enuff for quick death, just annoying monthly replacements and a few dramatic blow-outs.
And the time I connected a 120V:24V transformer, *backward*, so it tried to make 600V! On 35V caps! BIG hum like the transformer was fixin' to die. Probably would, too, if the wall-wires didn't burn first.
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"must be appropriate voltage and[[[[[ resistance]]]]] so the LED current does not go so high as to burn-out. "
Ok That statement was what I'm waiting for...BEFORE..I blow another lamp up (of which I just got two replacement)
Is resistance in a transformer "ma"? Can I plug any 4.5 volt transformer into this little piece of junk? The transformer I have is variable voltage and 1,000 ma.
Trust me. I have some idea how stupid this question might be.
I prefer not to blow another one.
Thanks, Terry
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I'd just stick with the batteries.
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Can I plug any 4.5 volt transformer
I have never seen a 4.5 volt tranny
Lots of 5 volt trannies out there which may be ok if they are running the LED's on the low side, current wise
Do you have a 4.5 volt DC tranny?
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It's a variable transformer. I also get all kinds of transformers from the salvation army. but this one doe's 1.5, 3. 4.5, 6 etc up to 12 volts
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I'd try the 3v setting first and then bump it to 4.5v it that don't work.
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Actually, there were 4.5 volt batteries in the old days..."C" batteries for battery radios. Not likely available these days...
My brother restores battery powered "farm" radios from the 20s, 30s etc, and builds power supplies for folks to run them on AC.
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Just my 2cents....are a lot of tranny's- iron core 4.5V.. for cd players, and the like. got a couple of those, and they're a lot o these multi V. trannys, or rather, power supplies, ...switch type, caps, some w/Vr, some w/resistors, 1.5,3,4.5-5,6,9,&12v. anywhere from $25 to $1...depending on store, swapmeet, Bodega. Bet it was a switch/cap job that blew.
Either way, great impetus towards 1st multi meter, learning to check for continuity,...Actual Voltage, versus what's stamped, (and the resulting Vdrop)... finding out about $ savers like diodes to add to houselights. save money, learn something, diy,...hopefully leave the fighting of menacing takeovers to my Daughter.....stop em overseas, before they get to Dad. Sorry for the Dad missing his little girl moment on the end there.
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Was the polarity of the transformer set correctly?
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8.16v DC measured at output w/120.8 AC at wall ..... they're popular with personal CD players and I think this one's broken and passing too much DC as it doesn'tp power 2 of my units which only run on batteries now...the cap usually goes south on these. The diodes usually hang on. Ez fix... but I'll probably have to open up the CD players and replace whatever resistor or diode that got over volted
Then again they can look like this in the same size package I actually pulled the sideboard off of this figuring one of those IC's went- only to come full circle and figured out that it was just that large cap that's now being replaced by the two in series . in all fairness I add that this one is a 8.5 and puts out 8.5 aand I was going to say I've never seen any 4.5 that have Transformer and switching Network like these but I have seen a lot of fives and what's a half a volt between friends unless you're doing a 2399 delay .
I know that it's an old Thread but I just ran across the transformer in an old moving box
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That will be unregulated.
so 4.5V at 600ma or 5.0V at 400ma and so on. They do tend to float high with no load.