Philo said:
Just saying be careful when it comes to looping wire through a toroidal transformer.
If you used some sort of current limiting (i.e. a resistor) to keep the current at just a few hundred milliamps (though you wouldn't need nearly that much if you're just wanting to light up an LED or two) I don't see any problem there.
But you're not going to get your 4 volts with just a few turns of wire. The voltage you get on the secondary is a function of the voltage across the primary and the turns ratio betwen the primary and secondary windings.
So let's say you have 120 volts on your primary. To get 4 volts on the secondary with only 6 turns would mean your primary would have to have (120/4) x 6 or 180 turns. Any low frequency (50-60 Hz) power transformer is going to have quite a few more than 180 turns on its primary.
Of course this is idealized and doesn't account for core losses and other realworld things that get in the way of the ideal but you get the picture.
What's the big deal about powering LEDs this way anyway?
se
Power incicators and such. I have used this technique for a year or so. Never actually measured the output of the windings, just did it on a recommendation a while back. Then I got a bunch of power switches for free but the had built in LEDs not incandesant bulbs. I tried used the same trick on my gainclone a few months back when I used one of them. I will try a few experiments when I get home though and make sure I fully understand the technique. Thanks.
Steve Eddy said:
For purist, it's isolating LED from rails, which never hurts. Some people claim that LEDs have effect on sonics, so this is to keep those folks happy
Some people don't know which rail to choose, so this solves their problem as well (some actually connect two LEDs, to keep rails balanced)I tried that trick, and believe me, I didn't need more than 10 turns to activate blue LED, which usually needs more voltage than red one. And transformer was fine too
In my current PS, i just don't install LEDs at all. Who needs them, if the amp is on all the time anyway?
Peter Daniel said:
Purist? What pruists are you talking about? Real purists don't use such superfluous, girly-man things like pretty lights. You must be talking about some panty-waist poseur purists who want their hairshirt and comfort too.
Some people claim that LEDs have effect on sonics, so this is to keep those folks happy
But it can bring about other problems (damaging windings drilling through center epoxy, getting the windings pinched between chassis and mounting hubs, etc.). Hell, just crack open an old wall wart and use a separate transformer. Or dig under the sofa cusions for some spare change and head over to Radio Shack.
Or wear your hairshirt proudly and stop your whining.
I tried that trick, and believe me, I didn't need more than 10 turns to activate blue LED, which usually needs more voltage than red one. And transformer was fine too
Yes. Well you're going to pick up a lot of stray field from the transformer's windings also. And all I was trying to say from the start is to be careful when looping coils of wire through toroids.
Now THAT'S the purist approach.
In the words of the Guess Who (though I like Lenny Kravitz's cover better), "colored lights can hypnotize. Sparkle someone else's eyes."
se
Yes, sure. But a friend of mine has a (unicat) Nixie- clock for more than 15 years, the tubes are about 200 mm high!
a very very freaky solution for CDP display would be decatrons.
An other friend of mine has in his garage some dozend small nixies from calculators... Maybe some day i find time i will use them with a mikrocontroller. If i find someone who writes the DSA output code.
a very very freaky solution for CDP display would be decatrons.
An other friend of mine has in his garage some dozend small nixies from calculators... Maybe some day i find time i will use them with a mikrocontroller. If i find someone who writes the DSA output code.
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