[Navyblue]

What I can think of:

- LED with a simple AC to DC circuit
- Some sort of light bulb

I have space constraint so I'd prefer not to go through the trouble of squeezing the AC to DC circuit into the enclosure.

If I were to use AC to power an LED, would it just blink at 50/60 Hz? Is there anyway of smoothing the blink with a capacitor?

Is there any better way?

Btw, is electronic fluorescent ballast found in screw in CFL a "noisy" device?

 

[MN Ham Phones]

An LED will work fine on AC. No blink. No need for "AC to DC circuit...."
You still need a series resistor to limit current regardless if you feed it AC or DC.

Feed it AC from low volt (heater winding) end of a transformer. Don't recommend feeding it AC from line voltage end of transformer.

I don't post often, but suggest you fill us in on what your project is.

 

[Navyblue]

Thanks.

Glad to hear that. I guess my stupid question prompted you to break your silence. It is for my Beta 22 build. I'll understand if you were to try to dissuade me from doing this.

 

[Uncle Erik]

There are a number of switches that have built-in LED indicator lights. Some of them just need a resistor to get them to the correct voltage.

 

[AudioCats]

if you use LED, there should still be a diode to convert it to DC, otherwise the reverse voltage can burn the LED. LED's can only withstand less than 10V in reverse.

 

[Navyblue]

Ok, you guys are confusing me.

As Uncle said, many power switch comes with LED, do they work with AC and just need a resistor to work off the mains?

If AC would fry LED in reverse polarity, would having resistors at both ends in series, or having a suitable diode at reverse polarity to shield the wrong end solve the problem?

 

[cotdt]

why not just use a standard AC light bulb?

 

[amb]

Some switches have neon bulbs and could work directly off AC. Some have a built-in LED with separate pins for the LED (either with or without an internal current-limit resistor). The assumption is that you'd power the LED with a DC voltage, and those with a built-in resistor must be operated at a specific rated voltage. If you don't have a DC voltage to work with, you could use AC to power the LED, but you should use a diode to block the reverse AC pulses from destroying the LED. The forward pulses are at AC frequency (50Hz or 60Hz depending on your local power standard), and that's fast enough that you won't see it as "blinking". No filtration capacitor is needed. The resistor value must be calculated based on the supply voltage, the desired forward current through the LED, and the LED forward voltage. The diode must be rated higher than the supply voltage with some headroom.

 

[Navyblue]

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif why not just use a standard AC light bulb?

I don't know what is the smallest AC bulb is, but I can't find any that are shorter than an inch, not to mention its extreme uncool factor when used on a non vintage themed build

If I were to mount it outside the case, I could use a lamp shade too and double it as a table lamp.

 

[Navyblue]

Quote:

Originally Posted by amb /img/forum/go_quote.gif Some switches have neon bulbs and could work directly off AC. Some have a built-in LED with separate pins for the LED (either with or without an internal current-limit resistor). The assumption is that you'd power the LED with a DC voltage, and those with a built-in resistor must be operated at a specific rated voltage. If you don't have a DC voltage to work with, you could use AC to power the LED, but you should use a diode to block the reverse AC pulses from destroying the LED. The forward pulses are at AC frequency (50Hz or 60Hz depending on your local power standard), and that's fast enough that you won't see it as "blinking". No filtration capacitor is needed. The resistor value must be calculated based on the supply voltage, the desired forward current through the LED, and the LED forward voltage. The diode must be rated higher than the supply voltage with some headroom.

Thanks for going through the trouble to make me a schematic.

Would the 1N400x line of diodes be suitable for this purpose? Well may be not the 1N4001. I should be using them off the Sigma 22's transformer secondary, could I just plug the LED and RLED (10k ohms I think) off the board and use them? I guess the values are about right?

 

[Pars]

Quote:

Originally Posted by Navyblue /img/forum/go_quote.gif Thanks for going through the trouble to make me a schematic. Would the 1N400x line of diodes be suitable for this purpose? Well may be not the 1N4001. I should be using them off the Sigma 22's transformer secondary, could I just plug the LED and RLED (10k ohms I think) off the board and use them? I guess the values are about right?

Now you have me confused... your title suggests that you are placing just the transformer in this enclosure? But now you are talking about a sigma22? In that enclosure? If so, of course you use the power LED and RLED of that board and you don't need to mess with what has been discussed.

 

[wolf18t]

I think Navyblue would like to install the o22 in the same enclosure b22 boards.

 

[amb]

If you're using one of the 30V secondaries to do this, then yes, a 10K ohm resistor is fine. Use a 1N4002 or above.

 

[Navyblue]

Thanks AMB.

Yes, the S22 will go to the main enclosure with the B22 and the transformer will go to its own enclosure.

 

[Navyblue]

I think I am using one of these.

The "LED voltage" says "12V". What does it mean? Forward voltage? 12V seems a little high to me. Specifically, what should the resistor value and wattage needed?