| Blue LED for BOSOZ, how to implement? - Click HERE for Original Thread |
| Yochim |
I am just about finished with my BOSOZ but I would like to have a blue LED on the front panel.
Should I take a feed off of the power supply rails to the LED? If so should I use a resistor in front of the LED?
Thanks for any info.
Y. |
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| fcel |
| Those blue led gets very bright. I suggest to start with a 200K resistor in front of the led. I remember someone on this forum install two leds - one on each rail - just so that it "looks balanced electrically". |
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| Yochim |
fcel, thanks for replying. Do I connect the LED directly to the power supply rail?
Thanks.
Y. |
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| AudioFreak |
| If you want it to be balanced electrically, connect it across the +ve and -ve rails (instead of +ve to gnd) and double the resistance. |
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| Peter Daniel |
| If you want to do it really well;) , put some extra turns of thin wire on your toroid and conect LED there with a small resistor. |
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| jh6you |
Waoowww...!
It's a fantasitc idea. Clap! Clap! Clap!
JH |
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| jh6you |
Yochim
I like the way as in the figure.
You could install LEDs of as many as number of diode bridges.
You could make them by easy p2p wiring.
JH |
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| skaara |
| You dont even need a bridge for led:bigeyes: |
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| stefanobilliani |
You may protect the led with 4 1n4004 series across its pins.
This metod limits the voltage at 2.5 volts or so.:att'n: |
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| skaara |
| But diodes will get hot, especially at that voltage?! |
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| stefanobilliani |
| :bigeyes: |
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| stefanobilliani |
This helps you when you play with resistor values.
Is a protection if you decide to put the led in parallel with a resistor in a PI filter. There , the the turn on voltage values may go as high as 6 or 7 volts
and so the led is protected. |
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| stefanobilliani |
| Oooops...:devilr: |
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| jh6you |
Hi, Friends
I have the diode bridges between the transformers and
the PS capacitors for my BOZ and Zen V2.
I just read the reference AC supply voltage at the bridge position,
e.g. 24V AC in case of my Zen V2. Meanwhile, my blue
LED lightens lovely when about 5mA currents flow thru it.
Therefore, I calculate the necessary resistor value in this way:
24 x 1.414 / 0.005 = 6787, i.e. about 7.5K ohms (watts?
24 x 1.414 x 0.005 = 0.17w).
In the same way,
if the AC supply is 30V, R of about 8.5K and
if 40V, R of about 11.5K and
if 50V, R of about 14K and
if 60V, R of about 17K...
If we know the AC supply value and the necessary current thru
LED for a lovely light, we can calculate the necessary resistor
easily. Try it.
JH |
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| skaara |
| stefanobilliani, i thought you would connect this without resistor, my mistake:angel: |
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| HarryHaller |
I saw the light, I saw the light
No more in darkness no more in night
Now I'm so happy, no sorrow in sight
Praise the Lord, I saw the light |
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| paulb |
| quote: | Originally posted by Yochim
Should I take a feed off of the power supply rails to the LED? If so should I use a resistor in front of the LED?
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Nobody answered his questions.
Yes. Yes.
Calculate R =
[(power supply voltage) - (LED voltage)] / (LED current)
Calculate power of the resistor =
[(power supply voltage) - (LED voltage)] * (LED current)
Double this (at least) to get a power rating for the resistor. You can put a bunch of resistors in series to use smaller-power resistors.
LED voltage, current are about 3V, 5 mA (look up the specs of the LED). Tweak resistor value to adjust brightness. |
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| HarryHaller |
Does anybody know how to do this with a green LED?
- removed obnoxious / rude / abrasive comment
editted by moderator. |
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| Peter Daniel |
| This could be more complicated because of a different voltage drop.;) |
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| yldouright |
HarryHaller
I shouldn't have to chase you around to get a simple answer to a question. Since when does enlightened mean stingy with information. I need to know which is correct if any:
(a)The Aleph-X source resistors power dissipation is 0.5V times the bias current through its mosfet.
(b)The Aleph-X source resistors power dissipation is the same as its mosfet.
(c)The Aleph-X source resistors power dissipation is the current through its mosfet squared times the source resistor value.
Since you guys are into short answers, I decided to make it easier for you. |
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| Peter Daniel |
| Supposing you have 0.5V drop on resistor, correct answer is a). The other two are wrong. |
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| yldouright |
Peter Daniel
Thanks. Now, what determines the maximum Voltage drop on these source resistors assuming an Aleph-X with +/- 25.6V rails? |
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| yldouright |
HarryHaller
I missed your reply, so don't think it was a snub to only thank Peter Daniel. So the current through the source resistor is equal to that which runs through its accompanying mosfet regardless of the power supply rails?
ex: 25.6V rails 0.5ohm source resistor and 1A through each mosfet. The source resistor in this case can be as low as 2W rated and do the job? |
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| jh6you |
Under the :bulb: of HH…
My ignorance shining…
Shining in the sky…
Towards the public…
Among others…
LED voltage drop…
That is non-zero…
That is to be greater than zero…
:headbash: ...
:whacko: ...
:headbash: ...
:whacko: ...
JH |
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| jh6you |
Reference: My attachment above.
At the joint between IN4004 and the resistor, I made a rough voltage-time curve. The voltage is prior to a consideration of the barrier voltage of about 0.66 in IN4004 and the LED voltage drop.
Now, I am ready to estimate the reliable size of the resistor based on the LED current. And, I could also estimate the time average power.
HH
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Does anybody know how to do this with a green LED?
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Maybe I simply paint it with my blue oil pen.
JH |
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| jag |
| Here are some led circuits I copied from somewhere sometime back. The circuit can be connected directly to 120V AC. The cap is used for voltage drop - the lower value of cap will provide higher impedance and hence dimmer light. |
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| WayneS |
The blue LEDs I've been using on my Aleph 2's are now down to
0.25 mA of current.
You connect the LED forward biased between the positive rail and the circuit ground. Don't worry about "electrical balancing" as
it is a minor effect and you'll never know any difference.
A LED if I'm not mistaken will conduct at a forward biased voltage of about 0.7V or so but it may be slightly higher. It is certainly not more than 2V.
Resistance = (voltage / current) to calculate the resistance you need. Just use the rail voltage of your amp and 0.00025 for the current and the resistance will be given in ohms.
Put the resistor between the positive rail and the LED's anode, and connect the LED's cathode to ground.
Forward biased means that the arrow on the LED symbol points from positive rail to ground on a schematic.
THe longer lead on the actual LED is the anode and is the lead that goes to the resistor which is connected to the positive rail of your supply.
OK, it's terse but I don't have a lot o time right now and I think I covered all your questions.... good luck. |
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| WayneS |
Oh, another quick thing or two...
the LEDS I used are Digikey P467-ND. THey're beauuuutiful.
I started out at 2 mA of current and I think I spot-welded part of my retinas from across the room at this current level. You definitely want the current to be low..... As I said I'm at 0.25 mA
now and that's about where I'm going to leave them I think.
W. |
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| stadams |
I have recently been doing some experiments with these LED's and agree that they do have a distinctive color. Wayne, if you think that your LED was bright you should try the other two variations of the LED that you have (P466 and P465.) They are both brighter by 2 and 4 times, respectively.
During the experiment these blue LED's showed a forward voltage drop of 3.0 V to 3.75 V with currents ranging from a couple of mA to 30 mA. The P466 was unbelievably bright at 30 mA--blindingly bright if directly infront. With optics they can transmit quite some distance.
On the DIY front, I was planning on using them to back light the heatsinks on one of my projects for a "Heavy Metal" type of effect.
Later, |
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| fcel |
Quick questions ....
When you guys turn off the Aleph 2 amps that uses the blue LED (P457-ND), does the light goes off gradually over a period of a few minutes or a few seconds?
And what is the reason behind why the LED lights go off slowly or quickly? |
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| AudioFreak |
| Depending on how you wire the amp and the LED it may go off immediately or fade out over a period of a few seconds or so. Usually when you turn off the amp, the power supply caps must discharge so the rails can go low. During this time, the LED will fade out. With a little additional circuitry, you can disconnect the rails immediately when power is cut. In this case, the LED goes out immediately. |
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| Ric Schultz |
LEDs add distortion that is audible. When I had an Aleph 3 the first thing I did was to remove the blue LED. It was wired from the positive supply to the output of one channel. Much better sound with it removed.
After you have put in an LED and listen for awhile, try removing it. Unless the LED is very isolated from the circuit on its own power supply and transformer, it should audibly mess up the sound. It makes the sound more grainy and two dimensional. More air and space and purity with them gone.
If you cannot hear it then fine. I personally have removed them on several amps, players, etc. always with good results.
Less is usually better!
Ric Schultz |
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| jh6you |
fcel
My understanding goes this way. After the power is switched off,
the main capacitors discharge themselves, partly through the LED of
small ampere eater. This is why the LED light fades off that slowly.
The bigger the main caps, the slower fading off.
For me, I use the little additional circuitry as indicated by AudioFreak.
You could find my circuitry in this thread. It works fine.
The light turns off immediately. I'm not kidding.
JH
Heck! I didn't read AudioFreak's writing carefully.
fcel, his explanation is better. |
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| WayneS |
Hmmmm... on the sound being better with the LEDs gone, I'm skeptical. But I'm open minded enough to remove it and see if I can hear any difference or not. Looks like a speriment to try this wknd... Since the cathode is connected to the signal ground, could it be that the recombination of the minority carriers is electrically noisy enough for it to affect the sound of the amp ? Maybe using R/2 between the cathode and ground, and R/2 between the supply and the anode will clean up the sound again ? Then the diode is isolated from the ground.... Or,
maybe connecting the anode to power through the limiting R and connecting the cathode to the chassis ground (isolated from signal ground by a thermistor) will work good... ideas to try.
I think you could use these blue LEDs at 30 mA to cut metal....
About the LEDs going out over time... since the caps in the power supply take time to discharge, the LED will be on for a few seconds. In my power amps with huge caps - 44000 uF per rail - the lights go out after the 3/4 second it takes to discharge. Then as the caps begin to generate a forward voltage again after the initial dscharge, the LEDs go back on at a low intensity and stay that way until the caps bleed down to 0 through some 100k resistors I added for that purpose. THis takes several minutes - like 10 or 20....
W. |
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| fcel |
Hey guys, I don't mean to drag this little LED issue to death but it has been bothering me lately. I want to get some feedback (thank you guys) before I tear my Aleph 2 amp (1 channel) apart.
I have 52,000uf per rail with 200K in series with the blue LED that is connected to the positive rail. On one channel, the LED light would go completely off in about 15 minutes like what Wayne says. But the other channel, it goes off in about 1 or 2 minutes. Both channel are constructed in exactly the same manner and 1 LED light goes off so quick that it bothers me. I would think that the LED light that goes off in about 15 minutes because of capacitor discharging is pretty normal but the other channel ... May be it's a partially defective LED? Possible? |
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| Peter Daniel |
| One explanation would be that these are not exactly same LEDs and one draws more current than the other. The best way to check it out would be switching them. If they produce the same amount of light you shouldn't be worried.:) |
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| fcel |
Yeah, they pretty much put out the same amount of light that I can see but it's this whole thing about Pass amp being "balancED", "monoblockED", "symmetricallED", "matchED" that drives me to get the LED light to go offED at the same time.
Well ... I will change out the LED on one of the weekends to see how it goes. |
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| WayneS |
If it's not too much trouble, I'd be thinking that the caps are defective and you might want to check them out. Just turn the amp on for a few seconds - maybe 10, then turn it off and draw a voltage vs time graph for the + rail for say every minute until it is discharged. Do this to the amp where the light is going out quickly. If it turns out that the LED is going out when there is significat rail voltage (these caps will go back up to about 7V or so after the initial discharge...) then replace the LED. If the caps in one amp behave much differently than the ones in the other, then I'd be pointing the finger at the caps (more than likely it will be only 1 of the pair if you have 2 paralleled) and then go the extra trouble of testing those after removing from the amps.
W. |
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| fcel |
| WayneS .... thanks for the troubleshooting suggestion. |
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| hifiZen |
slightly off topic, but...
I'm sure i'm not the only one who finds the glare from blue LEDs a problem, and would rather have a softer glow. I think this comes from the directional light emission pattern of the blue LED, so if you mount it directly on the front panel, it projects a beam of light out into the room.
I'm going to try something a little different... consider how a frosted light bulb has a far softer appearance compared to staring at the filament inside a clear bulb...
When I finally get around to building my Aleph-X amps, I'm going to mount the LED inside the case, and in it's place just mount a small sheet of clear plastic behind the hole. The outer surface of the clear plastic will be frosted to diffuse and disperse the blue backlight. It should look really nice, provided the hole isn't too deep. Maybe an extra-large countersink will be required, or perhaps a little milling / drilling on the backside, if the front panel is too thick. Perhaps a carefully applied blob of silicone or hot glue would do the trick, or a section of acrylic dowel? However it's done, the brightness could be adjusted either by changing the distance between the LED and lens, or adjusting the LED current. The colour could also be adjusted by combining different coloured LEDs... (maybe you're tired of blue?)
A major consideration will be to obtain the best on vs. off contrast by ensuring maxiumum darkness when the LED is off. This probably involves blacking out internal surfaces and closing the LED display off from other rear light sources, maybe by putting a small box or black tube behind the lens. Secondly, the frosted plastic can't be too opaque and "white" looking. That is, it can't reflect too much light from outside. Getting the right balance of diffusion vs. reflectivity might require some experimentation. If successful, the indicator should appear nice and dark during daytime when the amp is off, but the blue glow will not be offensive at night. |
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| hifiZen |
Too complicated?
Maybe all that's needed is to frost the front of the LED, then run it at real low current. Paint the inside of the mounting hole flat black, and after glueing the LED in, paint over it's backside with black paint as well?
Thoughts? Anyone tried any of this? |
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| Roberto Amato |
| quote: | Originally posted by hifiZen
Too complicated?
Maybe all that's needed is to frost the front of the LED, then run it at real low current. Paint the inside of the mounting hole flat black, and after glueing the LED in, paint over it's backside with black paint as well?
Thoughts? Anyone tried any of this? |
More or less. The Led is several cm. inside the cabinet (stand-alone power supply for BOSOZ) and there is a magnify lens on the front. Apparently the light comes from a much bigger source, but it's brightness is obvious only looking straight to it, otherwise is very very soft. |
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| Roberto Amato |
From another point of view, the complete BOSOZ. The Led is off
in this one. |
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| macka |
Following your posts today decided to install a bright blue Led on Wayne S pcs to see how it would go.
The rating is 3.6 volt 20 ma, I am using the original resisitor for the Aleph 2 and it is plently bright enough.
So much so that it adds a great effect at night when you can see the blue aura from the side ventilation areas around the heats which I use to control internal air temparature.
My On rocker switch on the front panel has an inbuilt illuminated Red neon bezel, so the two colours look great.
regards
macka |
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| fcel |
Roberto .... that's beautiful ... how about some interior pictures? Is this the one with the gears controlling the two 2-gang pot?
May be you should start a new thread for these pictures. |
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| Roberto Amato |
| quote: | Originally posted by fcel
Roberto .... that's beautiful ... how about some interior pictures? Is this the one with the gears controlling the two 2-gang pot?
May be you should start a new thread for these pictures. |
Yes, it's the one with the gears... ok, i'll put the photos in a new thread.
ciao,
Roberto |
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| Tomo |
JAG -
I am testing your 120V version. But I have a question. What is the wattage requirement for the resistor? I am using 1/4W. Do I need more?
It turns on ... I wonder if the resistor overheat and burn.
Tomo |
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| Tomo |
Blah!
Yep it's hot. I can cook something on it.
Capacitor charge is still there when you power-off. So you shouldn't offer yourself as a conductive path. ... :)
Tomo |
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| hifiZen |
| quote: | | From another point of view, the complete BOSOZ. The Led is off in this one. |
Wow, that's <i>gorgeous!</i> Please do post more pics! :) What kind of wood and finish are the side panels? Maybe some day I can make something which looks so good...
Thanks Roberto! |
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| hifiZen |
oops, I didn't see your other thread. the mahogany looks great!
Cheers, |
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| jag |
| quote: | Originally posted by Tomo
What is the wattage requirement for the resistor? I am using 1/4W. Do I need more?
Tomo |
At 60Hz the capacitor reactance is about 5650 ohms which means about 10mA avg current corresponding to 1/10 watt dissipation in the 1K resistor (at steady state). There is going to be an inrush current initially and, I think, 1/2 to 1 watt should do it.
| quote: | | Capacitor charge is still there when you power-off. So you shouldn't offer yourself as a conductive path. ... |
You should be very careful, always, when dealing with line voltages. |
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| Tomo |
JAG -
Thank you. I feel a lot better now. I have imbedded your LED design into my amp. I used .47uF with four 1W 1K metal oxide resistors (to build 2W 1K resistor. I couldn't find 1K high wattage resistors in my box)
It lits up my room pretty good. It was kinda weird having a blue spotlight, but I now found it quite soothing.
Tomo |
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| lopan |
| my LEDs turn off immediately but the music will play on for a minute or more depending of the volume |
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| lgreen |
Did someone say Blue LEDs???? BOSOZ with LEDs. I've got over a dozen on my BOSOZ, including blue LED switches!
My Web Page
I made a special PCB for the LEDs, it first passes the signal through a diode, then a fixed resistor, then a multiturn trimpot. This way I get to adjust the brightness of the LEDs, because when you have 19 or 20 you just can't have them different intensities.
Here is the board (its from my Gainclone, but the same board is in the BOSOZ, just don't have a good pic of it).
Also, I put some LEDs inside the case offset from the outside. I couldn't get any frosted glass to diffuse the light so I bought a package of microscope slides and cut off the frosted end used for labels. You see the results of that here. |
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| gmphadte |
Tomo
refer this
thread |
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