How to Tell If The LED Is Regulated
- Thread starter ragweed
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hank
Flashlight Enthusiast
> I assume regulated is better?
Nobody named "John Galt" is likely to answer "yes" to that question (grin).
Unregulated -- starts off brighter, gets dimmer as it pulls the battery voltage down immediately (load) and starts dimmer each time as the battery is more used up.
Regulated -- depends, that can mean a lot of different things.
site:candlepowerforums.com "model name" "model number"
An image search might pull up charts showing brightness over time.
Nobody named "John Galt" is likely to answer "yes" to that question (grin).
Unregulated -- starts off brighter, gets dimmer as it pulls the battery voltage down immediately (load) and starts dimmer each time as the battery is more used up.
Regulated -- depends, that can mean a lot of different things.
site:candlepowerforums.com "model name" "model number"
An image search might pull up charts showing brightness over time.
carrot
Flashaholic
Regulation can mean all sorts of things. Rather than ask whether a light is regulated it can make more sense to ask how a light is regulated, to which the simple answer is a graph, showing light output over time. We like to call these "runtime graphs."
PhotonWrangler
Flashaholic
Tune an AM radio to an empty spot at the low end of the dial.
Turn on the flashlight and hold it near the radio.
A regulated flashlight will produce an audible whine in the radio.
This is produced by the oscillator in the regulation circuit.
kramer5150
Flashaholic
on some direct driven lights if you remove the tailcap wet your finger and touch -B to the body end the LED will dimly illuminate.
balou
Enlightened
And some flashlights make an audible whine all by themselves.
PhotonWrangler - isn't it the inductor which makes the whine? Of course it's oscillating, and you might call it an LC oscillator... but I like nitpicking
PhotonWrangler
Flashaholic
And some flashlights make an audible whine all by themselves.
PhotonWrangler - isn't it the inductor which makes the whine? Of course it's oscillating, and you might call it an LC oscillator... but I like nitpicking
Technically it's the RF harmonics being radiated by the inductor and surrounding components. The RF field is produced by harmonic rich square waves produced as a product of the oscillator in the switching regulator circuit.
Sometimes an audible whine can be heard even without a radio because some of the energy in the unit's oscillator produces a varying electromagnetic field that falls within the baseband audio range, causing nearby ferrous metals (including the transformer's frame) to vibrate.
Close enough? :huh:
hank
Flashlight Enthusiast
I love this place. There's always more to know.
TorchBoy
Flashlight Enthusiast
csshih
Flashlight Enthusiast
holy crap, photonwrangler... did NOT know that at all.. I shall go try it out now!!
edit: curse. AM antenna is missing hmmm...
edit: curse. AM antenna is missing hmmm...
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PhotonWrangler
Flashaholic
Even if the antenna is missing, it will work by holding the flashlight close to the body of the radio (unless it's a car radio).
HKJ
Flashaholic
If you by regulated, means light with stable output, then both regulated and unregulated lights can use a driver and the driver might or might not emit any radio frequency radiation.
kramer5150
Flashaholic
I don't understand how this tests for light output regulation? It seems more like a test for EMI/RFI radiation.
PhotonWrangler
Flashaholic
It's a quick test to see if there is a regulator circuit inside, as opposed to a simple current limiting resistor. A resistor will not emit any RFI.
kramer5150
Flashaholic
What if the regulator circuit is sufficiently shielded, and does not emit RFI (or not enough to be amplified over an AM radio).
My eagletac P100C2 (for example) is a circuit we all know to be ruler-flat regulated and it does not cause noise and RFI on my AM radios. I am listening to my local NFL game as I type this. I had to secure the AM loop antenna on the back of my receiver this morning... no RFI at all.
**edit**
Just checked with my ITP-A3... no RFI.
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PhotonWrangler
Flashaholic
There will be those flashlights that are so well shielded that they won't emanate any significant RFI, so it's not a foolproof test. It's just something that you can do in 30 seconds without having to tear down the flashlight to look for a regulator board. Most of my lights radiate at least a little bit of RFI, and when I tune my handheld AM radio to an empty spot on the low end of the band, that causes the radio to open up it's RF AGC all the way so it runs at maximum sensitivity.
An AM radio will also pick up other unusual sources of "sounds." Try placing the radio next to a calculator, punch in a large number, press [square root] and listen. It will play a short musical tune.
**EDIT** BTW my Fenix P3D-CE makes a combination of a whine and a rushing sound in an AM radio. The pitch of the sound changes with the brightness setting.
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balou
Enlightened
PhotonWrangler
Flashaholic
Yeah I think that explanation was free of amibiguities of any kind
Always happy to indulge a fellow nerd! :buddies:
