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Blue LED Dial Lights. (Or other colors)

William Barrett, KW1B All Messages By This Member #24499 Assembled Electro-Lords: Ya know,? I saw those advertised somewhere a while back and a guy who?I resepct for his technical savvy?said they were a bad idea. His thesis was that LEDs occasionally go bad in a "short" mode, unlike conventional bulbs that virtually always blow "open."? He said a shorted LED could burn out the filiment winding on the power transformer.? Sounded kinda hyper-picky to me; I never saw a LED fail in?dead short mode, myself.? (..and I bin doin' this for a few decades.) ? Was he right?? ? If not, I have number of things I'd like color LEDs for the dials and meters... ? (I sold the Drakes a while back, but the point remains.) ? ? 73 KW1B
Jerry Miel All Messages By This Member #24503 开云体育 I assume that LED's are much like transistors and other SS devices.? Open transistors almost always started as shorted transistors but the very fine wires that connect the silicon wafers to the leads will burn out immediately with a short even with very little current available.? It is almost like a microamp fuse.? I would expect that a shorted LED would burn open long before the transformer would feel it.? Just my opinion. Jerry On 10/1/2022 9:47 AM, William Barrett, KW1B via groups.io wrote: toggle quoted message Show quoted text Assembled Electro-Lords: Ya know,? I saw those advertised somewhere a while back and a guy who?I resepct for his technical savvy?said they were a bad idea. His thesis was that LEDs occasionally go bad in a "short" mode, unlike conventional bulbs that virtually always blow "open."? He said a shorted LED could burn out the filiment winding on the power transformer.? Sounded kinda hyper-picky to me; I never saw a LED fail in?dead short mode, myself.? (..and I bin doin' this for a few decades.) ? Was he right?? ? If not, I have number of things I'd like color LEDs for the dials and meters... ? (I sold the Drakes a while back, but the point remains.) ? ? 73 KW1B
Dale Parfitt #24504 开云体育 The bayonet LED’s have a built in? current limiting resistor- depending on voltage and color, 470 Ohms is a common value. ? Dale W4OP ? toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Miel Sent: Saturday, October 1, 2022 3:20 PM To: [email protected] Subject: Re: [HallicraftersRadios] Blue LED Dial Lights. (Or other colors) ? I assume that LED's are much like transistors and other SS devices.? Open transistors almost always started as shorted transistors but the very fine wires that connect the silicon wafers to the leads will burn out immediately with a short even with very little current available.? It is almost like a microamp fuse.? I would expect that a shorted LED would burn open long before the transformer would feel it.? Just my opinion. Jerry On 10/1/2022 9:47 AM, William Barrett, KW1B via groups.io wrote: ? Assembled Electro-Lords: ? Ya know,? I saw those advertised somewhere a while back and a guy who?I resepct for his technical savvy?said they were a bad idea. His thesis was that LEDs occasionally go bad in a "short" mode, unlike conventional bulbs that virtually always blow "open."? He said a shorted LED could burn out the filiment winding on the power transformer.? Sounded kinda hyper-picky to me; I never saw a LED fail in?dead short mode, myself.? (..and I bin doin' this for a few decades.) ? Was he right?? ? If not, I have number of things I'd like color LEDs for the dials and meters... ? (I sold the Drakes a while back, but the point remains.) ? ? 73 KW1B
William Barrett, KW1B All Messages By This Member #24505 Ya know....? Come to think of it...? I shudda remembered that. Thanks ? ?73 KW1B toggle quoted message Show quoted text From: "Dale Parfitt" <PARINC1@...> To: [email protected] Sent: Saturday, October 1, 2022 3:34:17 PM Subject: Re: [HallicraftersRadios] Blue LED Dial Lights. (Or other colors) The bayonet LED’s have a built in? current limiting resistor- depending on voltage and color, 470 Ohms is a common value. ? Dale W4OP ? From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Miel Sent: Saturday, October 1, 2022 3:20 PM To: [email protected] Subject: Re: [HallicraftersRadios] Blue LED Dial Lights. (Or other colors) ? I assume that LED's are much like transistors and other SS devices.? Open transistors almost always started as shorted transistors but the very fine wires that connect the silicon wafers to the leads will burn out immediately with a short even with very little current available.? It is almost like a microamp fuse.? I would expect that a shorted LED would burn open long before the transformer would feel it.? Just my opinion. Jerry On 10/1/2022 9:47 AM, William Barrett, KW1B via groups.io wrote: ? Assembled Electro-Lords: ? Ya know,? I saw those advertised somewhere a while back and a guy who?I resepct for his technical savvy?said they were a bad idea. His thesis was that LEDs occasionally go bad in a "short" mode, unlike conventional bulbs that virtually always blow "open."? He said a shorted LED could burn out the filiment winding on the power transformer.? Sounded kinda hyper-picky to me; I never saw a LED fail in?dead short mode, myself.? (..and I bin doin' this for a few decades.) ? Was he right?? ? If not, I have number of things I'd like color LEDs for the dials and meters... ? (I sold the Drakes a while back, but the point remains.) ? ? 73 KW1B
Pat Ryan All Messages By This Member #24506 开云体育 Yeah I’m a bit worried about this myself I have one on an 8amp 6.3v fil supply to a home brew audio amp would not the dropping resistor blow and protect the transformer ? Come to think of it I have one on the B+ too about 350v @ 150ma would not the dropping resistor blow in the event of a short? It never happened to me either but I often think about it. I suppose ideally you could put a fuse in line to protect the transformer… ? 73 de Pat/EI7CN ? Sent from for Windows ?
don Root All Messages By This Member #24507 开云体育 The ?idea that? a “device”? is? found?? to be failed due to a short?? or failed due to an open likely depends highly on ALL the details of it’s guts, and maybe the circuit that it sits in. ? Jerry points out a case where an initial failed short event? quickly becomes a failed open situation, presumably because there is lots of available current in the supply circuit. As to Dale’s comment; ?does the 470 Ohms? just limit the peak current as the Led fails from short to open or does it allow the LED to remain shorted indefinitely, while the resistor heats up. ? Now .. I am just asking … the only thing I know about newer whitish/blueish ?LEDS? is that fuming things hurt my eyes!!!! Don VA3DRL ? toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Dale Parfitt Sent: Saturday, October 1, 2022 3:34 PM To: [email protected] Subject: Re: [HallicraftersRadios] Blue LED Dial Lights. (Or other colors) ? The bayonet LED’s have a built in? current limiting resistor- depending on voltage and color, 470 Ohms is a common value. ? Dale W4OP ? From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Miel Sent: Saturday, October 1, 2022 3:20 PM To: [email protected] Subject: Re: [HallicraftersRadios] Blue LED Dial Lights. (Or other colors) ? I assume that LED's are much like transistors and other SS devices.? Open transistors almost always started as shorted transistors but the very fine wires that connect the silicon wafers to the leads will burn out immediately with a short even with very little current available.? It is almost like a microamp fuse.? I would expect that a shorted LED would burn open long before the transformer would feel it.? Just my opinion. Jerry On 10/1/2022 9:47 AM, William Barrett, KW1B via groups.io wrote: ? Assembled Electro-Lords: ? Ya know,? I saw those advertised somewhere a while back and a guy who?I resepct for his technical savvy?said they were a bad idea. His thesis was that LEDs occasionally go bad in a "short" mode, unlike conventional bulbs that virtually always blow "open."? He said a shorted LED could burn out the filiment winding on the power transformer.? Sounded kinda hyper-picky to me; I never saw a LED fail in?dead short mode, myself.? (..and I bin doin' this for a few decades.) ? Was he right?? ? If not, I have number of things I'd like color LEDs for the dials and meters... ? (I sold the Drakes a while back, but the point remains.) ? ? 73 KW1B
Phil Patton #24522 If I were ever that paranoid, for even a second, I would get over it very quickly realizing that the LED is going to need a dropping resistor (and a diode). So hams include some of the most paranoid humans ever.? On Sat, Oct 1, 2022, 11:47 AM William Barrett, KW1B via <wbarrett=[email protected]> wrote: toggle quoted message Show quoted text Assembled Electro-Lords: Ya know,? I saw those advertised somewhere a while back and a guy who?I resepct for his technical savvy?said they were a bad idea. His thesis was that LEDs occasionally go bad in a "short" mode, unlike conventional bulbs that virtually always blow "open."? He said a shorted LED could burn out the filiment winding on the power transformer.? Sounded kinda hyper-picky to me; I never saw a LED fail in?dead short mode, myself.? (..and I bin doin' this for a few decades.) ? Was he right?? ? If not, I have number of things I'd like color LEDs for the dials and meters... ? (I sold the Drakes a while back, but the point remains.) ? ? 73 KW1B

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