Blue Diode as Power Indicator

Panelhead · 16th February 2003, 11:27 PM

As it seems the blue LED is the only way to go for a power indicator, I have a dumb question. I read where others have wrapped a couple of turns around the toriodal power transformer to energize the light.
I just ordered a couple of Lumex "Ultra Super Blue" panel mount LED's for my upcoming projects. My question is how the diode lives with the AC coming off the transformer.
I trust others, but most I have seen work off the DC heaters on tube gear. Can you feed them AC without smoking these 5.00 each jewels?

TIA,
George

Nelson Pass · 16th February 2003, 11:33 PM

I have never done this. It's a lot easier to simply
place the LED in series with a resistor between the
+ and - supplies. Makes a nice supply bleed-down
circuit, also.

jackinnj · 16th February 2003, 11:50 PM

super blues -- Agilent high lumninosity are less expensive.

Peter Daniel · 17th February 2003, 12:09 AM

In my latest Gainclone project it was more convenient for me to wrap 10 extra turns on a toroid for a blue led. I connected it through regular rectifying diode and intensity adjustment resistor. Works fine.

Panelhead · 17th February 2003, 10:22 AM

Thanks for the advice on parts needed. I will wrap wire and measure voltage untill it gets to the proper range.
If there are replacements needed I will look into the Agilent LED's. The blue models are not available locally. But that is what is great about the net!

George

miguel2 · 17th February 2003, 11:17 AM

I use some turns of bell wire around the toroid to get ~ 8V, a diode after, a cap and the led. The value of the cap controls the intensity of the led.

Panelhead · 18th February 2003, 01:06 AM

Some have metioned a series resistor, you are using a shunt cap for filtering?

cyclotronguy · 20th February 2003, 05:53 PM

Cap is for current limiting..... placed in series

ElectroNick · 20th February 2003, 09:22 PM

Beware of the orientation of the elko when placing it in series with a led

!

miguel2 · 21st February 2003, 08:10 AM

I put the cap after a rectifier diode, from the +V to ground. Then it is the blue led. I did it to get some ripple off the line voltage to the blue led. Now that I think of it maybe it is a silly idea, but it works. The bigger the cap the higher the voltage the blue led sees, that is why the cap is controlling the light intensity.

16th February 2003, 11:27 PM	#1
Panelhead diyAudio Member Join Date: Dec 2002 Location: Houston	Blue Diode as Power Indicator As it seems the blue LED is the only way to go for a power indicator, I have a dumb question. I read where others have wrapped a couple of turns around the toriodal power transformer to energize the light. I just ordered a couple of Lumex "Ultra Super Blue" panel mount LED's for my upcoming projects. My question is how the diode lives with the AC coming off the transformer. I trust others, but most I have seen work off the DC heaters on tube gear. Can you feed them AC without smoking these 5.00 each jewels? TIA, George

16th February 2003, 11:50 PM	#3
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	it is a diode after all super blues -- Agilent high lumninosity are less expensive.

17th February 2003, 12:09 AM	#4
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	In my latest Gainclone project it was more convenient for me to wrap 10 extra turns on a toroid for a blue led. I connected it through regular rectifying diode and intensity adjustment resistor. Works fine. __________________ www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

17th February 2003, 10:22 AM	#5
Panelhead diyAudio Member Join Date: Dec 2002 Location: Houston	Blue diode wiring Thanks for the advice on parts needed. I will wrap wire and measure voltage untill it gets to the proper range. If there are replacements needed I will look into the Agilent LED's. The blue models are not available locally. But that is what is great about the net! George

18th February 2003, 01:06 AM	#7
Panelhead diyAudio Member Join Date: Dec 2002 Location: Houston	I assume this is a shunt cap Some have metioned a series resistor, you are using a shunt cap for filtering?


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

16th February 2003, 11:33 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	I have never done this. It's a lot easier to simply place the LED in series with a resistor between the + and - supplies. Makes a nice supply bleed-down circuit, also.

17th February 2003, 11:17 AM	#6
miguel2 diyAudio Member Join Date: Jun 2002 Location: Portugal	I use some turns of bell wire around the toroid to get ~ 8V, a diode after, a cap and the led. The value of the cap controls the intensity of the led.

20th February 2003, 05:53 PM	#8
cyclotronguy diyAudio Member Join Date: Sep 2001 Location: Northern California	Cap is for current limiting..... placed in series

20th February 2003, 09:22 PM	#9
ElectroNick diyAudio Member Join Date: Dec 2002 Location: The Netherlands	Beware of the orientation of the elko when placing it in series with a led !

21st February 2003, 08:10 AM	#10
miguel2 diyAudio Member Join Date: Jun 2002 Location: Portugal	I put the cap after a rectifier diode, from the +V to ground. Then it is the blue led. I did it to get some ripple off the line voltage to the blue led. Now that I think of it maybe it is a silly idea, but it works. The bigger the cap the higher the voltage the blue led sees, that is why the cap is controlling the light intensity.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Power On Indicator Light	pengboon	Tubes / Valves	4	4th March 2008 10:31 PM
Gross power indicator	Zero Cool	Equipment & Tools	24	25th December 2007 06:32 AM
hybrid power supply: diode bridge into diode tube	engels	Tubes / Valves	8	24th September 2007 09:18 AM
Anyone ever us a 6AF6G as a power indicator?	Wardsweb	Tubes / Valves	6	20th June 2003 12:08 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read