Runnin LED off heaters.

[joesatch]

12vdc heaters.   Is this the correct way?

[shaun]

I have successfully run LEDs off the 6v tap using a single 180ohm resistor and nothing else. The value of the resistor changes the brilliance of the LED of course.

The diode is designed to stop the AC flickering which is occasionally apparent without one. The purpose of the diode is turn the AC into DC, so install where that would be most effective. Your diagram seems to allow AC to run through the diode, so I think you'd have to install it on one leg before the LED, a la the image I'm attaching.

[sluckey]

12vdc heaters.   Is this the correct way?

That will work but I suggest a 1K resistor. Oh, and the cathode of the diode ***MUST*** connect to the anode of the LED in your drawing.

[joesatch]

12vdc heaters.   Is this the correct way?

That will work but I suggest a 1K resistor. Oh, and the cathode of the diode ***MUST*** connect to the anode of the LED in your drawing.

since you mention that, a related question. On my relays there is  a diode with cathode to positive (as per my schematics and what I've found online through research) . I'm not sure if this is correct because the relay board i bought shows cathode to negative (unless i have the board upside down). Which way is correct? I did find one source that states it doesnt matter.

[sluckey]

On my relays there is a diode with cathode to positive

That's correct. I suggest spending a few minutes on google to find out what that diode does.

[EL34]

Hint: Relay coil 

[joesatch]

diode cathode to coil positive for noise suppression. i guess. many sources claim the polarity doesnt matter

[sluckey]

many sources claim the polarity doesnt matter

That's bullshit!

[joesatch]

i should clarify. they say the polarity doesnt matter for the relay coil, cant speak for the diode still researching this.

[acheld]

Try searching for flyback diodes.

You might know that inductors induce current flow when they are energized, hence diodes are commonly used with relays to mitigate noise elsewhere in the circuit.

[Williamblake]

I am running leds from heaters in one build and instead of a diode i put in a second led with reverse polarityin paralel with the other led. Resulting in movie quality flicker reduction but if it didnt shine through coloured glass you would still notice it. Powering the status led with the bleeder/heater elevation circuit is my weapon of choice now.

[joesatch]

Not alotta resources for running LED's out there. Ideally i'd like to have 3 LED's, one for power and the other two for channel 1 channel 2

[EL34]

Not alotta resources for running LED's out there. Ideally i'd like to have 3 LED's, one for power and the other two for channel 1 channel 2

I have some diagrams here
https://el34world.com/projects/relay_switch.htm

And here is my LED calculator
https://el34world.com/php/LedCurrent/LedCurrent.htm


All this stuff and more is on the library page here
https://el34world.com/schematics.htm

[thetragichero]

Not alotta resources for running LED's out there

does there need to be? 1n400x (i don't stock anything besides 1n4007 because it'll work anywhere a lower voltage diode of that series will) antiparallel to your led and some sort of dropping resistor. i use led as indicator tapped off the filament string for everything because leds (and their bezels) are dirt cheap and use very little current
for something on the front panel near the preamp/controls to indicate channel i would use dc as running your filament string up there will likely cause hum issues

[sluckey]

If you will have multiple LEDs and relays you should consider building a small power supply for all.

[acheld]

I've been using "Meanwell" power supplies for this purpose, usually at 12VDC.  They are small, not expensive, and seem to work well.  I've had no problems with noise -- yet.

Doug has a nice little board which is designed for a 5VDC (IIRC) regulator.   Do look at his LED resources -- he has a lot experience with them.

for something on the front panel near the preamp/controls to indicate channel i would use dc as running your filament string up there will likely cause hum issues

It could, though it has not for me. That said, I've adopted a Blackface design philosophy -- my amps all look like a DR design/layout (whatever the circuit), and I keep the AC (and power) to one side and the preamp to the other.   I know, boring, right?  Anything for a quiet life.

[joesatch]

it worked out well. I went with the 1k as per sluckey. a little bright but it'll do. ran it off the 12vdc heater tap with the diode as well.

[EL34]

it worked out well. I went with the 1k as per sluckey. a little bright but it'll do. ran it off the 12vdc heater tap with the diode as well.

If you use my LED calculator, it will tell you what the value of the current limiting resistor should be
Then there is no guessing
I linked to it up above


I like to measure the actual current and set LED's to 20ma
Many LED's will run at 30ma, but I scale it back a bit

[thetragichero]

when I'm using the water clear super bright leds (as tayda calls them) on the 6v filament tap I'll usually use 10k (from my "reclaimed parts" bin) and it's still incredibly bright. setting them for 20ma is a good idea though as mentioned above

[joesatch]

i tried 10k and it helped but still pretty bright, how do i reduce the current? there's a couple of websites but i dont have a PhD to figure out what they're talking about. I would like to get my LED's brightness way down

[thetragichero]

V = I R
you reduce current by either reducing voltage (probably a bad idea on a tube filament tap) or increasing resistance

[joesatch]

ok so i'll try a 22k resistor

[EL34]

ok so i'll try a 22k resistor

Why don't you stop guessing and get the exact value current limit resistor?

I gave you the link to the LED calculator
https://el34world.com/php/LedCurrent/LedCurrent.htm

Just drop in a couple values and get things done right.

[joesatch]

ok so i'll try a 22k resistor

Why don't you stop guessing and get the exact value current limit resistor?

I gave you the link to the LED calculator
https://el34world.com/php/LedCurrent/LedCurrent.htm

Just drop in a couple values and get things done right.

Honestly all i know from the equation is the supply voltage (12vdc). I have a box of diodes unlabelled and i dont know their current or voltage requirements. Everything i read says you need to reduce the current not only the voltage. With dropping resistors i know how to reduce the voltage, the current on the other hand i dont know how that can be reduced.

[EL34]

No, you have the voltage and 20ma of current
Or whatever ma current you want to run the LED at.


Plug those values into the calculator to get the current limit resistor value
If that value does not land on a common value, plug those two values into the other calculator to see what current the LED will run at.
Plug in 12volts and the

That's why I programmed two different calculators

You should know the operating voltage of the LED from where you purchased it.

Example from the calculator
Current Limiting Resistor value = 450 Ohms
Formula = (12 Volts - 3 Volts) / 20 Milliamps = 450 Ohms

So 450 ohms is not a common value
Then I used the other calculator with 470 ohms

LED current = 19.148936170213 milliamps
Formula = (12 Volts - 3 Volts) / 470 Ohms = 19.148936170213 Milliamps

[sluckey]

No, you have the voltage and 20ma of current
Or whatever ma current you want to run the LED at.

But he doesn't know the LED operating voltage. Without that info, the calculator can't work. It's probably much faster to just use a larger resistor to lower the brightness.

[EL34]

You can guess at 2 volts to be safe



The LED's I sell all have a chart for the voltages
https://el34world.com/Forum/index.php?topic=27741.0

[joesatch]

all i know is suggestions and examples i see are way off. They say use anywhere between 400 ohms and 1k. i'm up to 10k and still too bright. I will put a 33k and see what happens

[EL34]

all i know is suggestions and examples i see are way off. They say use anywhere between 400 ohms and 1k. i'm up to 10k and still too bright. I will put a 33k and see what happens

Well the, just go up in value until you get the brightness you want.
In this case, you will not be over driving the LED because you are dropping the current

[joesatch]

thanks, i've put a second LED for the drive channel as well. I will play with the values. From what i understand different color LEDs can differ in brightness

[shooter]

fwiw
you can grind off the "dome" of the LED to help diffuse light
you can also buy bezels for LEDS that also diffuse light