LED burnout! 6.3 VAC

[Mook]

So, I did what Doug says (putting a 180R in series with one lead of your LED) in a 6.3 VAC and I had LED burnout....fizzle......burn smells.

Should I have used a bigger or smaller R value?      My voltage without tube load is 7.1 VAC.


Thanks!!!


Mook

[kagliostro]

More resistance = more voltage drop

About LED you must consider the current that flows

K

[Mook]

More resistance = more voltage drop

About LED you must consider the current that flows

K

So, it's impossible to use an LED?    What would be a solution?

[EL34]

So, I did what Doug says (putting a 180R in series with one lead of your LED) in a 6.3 VAC and I had LED burnout....fizzle......burn smells.
Should I have used a bigger or smaller R value?      My voltage without tube load is 7.1 VAC.
Thanks!!!
Mook

What LED did you use?
What is the LED's specs?

7.1vac is different than 6.3vac

My LED calculator shows you the value you need to use once you know the forward voltage and current max
http://el34world.com/php/LedCurrent/LedCurrent.htm

[Mook]

So, I did what Doug says (putting a 180R in series with one lead of your LED) in a 6.3 VAC and I had LED burnout....fizzle......burn smells.
Should I have used a bigger or smaller R value?      My voltage without tube load is 7.1 VAC.
Thanks!!!
Mook

What LED did you use?
What is the LED's specs?

7.1vac is different than 6.3vac

My LED calculator shows you the value you need to use once you know the forward voltage and current max
http://el34world.com/php/LedCurrent/LedCurrent.htm

I dunno the LED specs.......as it was from a bin of parts.    Should prolly order ones with known specs/values.

Thanks!

[EL34]

I see you ordered one of my super bright LED's just now, thanks

Specs for that LED are
3.6 volts forward voltage
max current around 30 ma - Run it at 20 ma to be safe

From my LED calculator
Result # 1
Current Limiting Resistor value = 175 Ohms
Formula = (7.1 Volts - 3.6 Volts) / 20 Milliamps = 175 Ohms
Use your browser back button to go back to the Calculator page

result #2 - Using a 180 ohm current limiting resistor

LED current = 19.4444444444 milliamps
Formula = (7.1 Volts - 3.6 Volts) / 180 Ohms = 19.4444444444 Milliamps
Use your browser back button to go back to the Calculator page

[EL34]

Once you have tubes in and drawing heater current that 7.1 vac will come down and the LED will be running less current than at the 7.1 vac calculation


You can probably calculate maximum current of 30 ma at the 7.1 vac if you want the LED's to be brighter when the tubes are all in

[Mook]

Ok....got my LED problem worked out.    Seems one wire in my twisted pair was touching ground.

I am currently using 180R in series with the LED.

The LED is the ones that Doug sells.


Thanks, All!

Mook

[PRR]

> fizzle......burn smells.

I think you wired it wrong. Even if the LED had near-zero voltage drop, 7.1V only causes 40mA of current. This is a bit high, but nearly any LED will stand it for a long time. Also the LED *will* have voltage drop, 2V easy, so 5.1V in 180 Ohms is 28mA. Also if you feed AC, half the time the LED will be "blocking", so the average is 14mA, well within the limits of any LED I know.

Check that "180" resistor, color-stripes but also put your ohm-meter on it. It might be an "18". Worse, it may be fine but read zero because of a solder-blot or wire-hair behind it.