Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
Everyone is quite right about the adjustable power supply suggestion. I was fixated on the power supply issue without considering the nature of the load. I like Walt's suggestion of simply switching in more LEDs as needed. A rotary switch adding more LEDs with each position would make adjusting the light level easy with a simple turn of the knob. It may be "brute force" as Walt says, but sometimes the simplest is also the most elegant and efficient solution. 73, Ron AC7AC -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Walter Underwood Sent: Saturday, January 7, 2017 8:08 AM To: Elecraft Reflector Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed A brute force solution would be to get four LED lighting strips that run off 12V and use four switches. Turn on as much light as you want. wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
A brute force solution would be to get four LED lighting strips that run off 12V and use four switches. Turn on as much light as you want. wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) > On Jan 7, 2017, at 6:32 AM, Chip Stratton wrote: > > What John says is true. Over time the forward voltage drop of an LED will > decrease somewhat as it ages. It isn't great, and it isn't fast, though it > happens more quickly initially. > > The forward voltage drop decreases more dramatically in the short term with > temperature - the higher the die temperature, the lower the forward voltage > drop. This can result in thermal runaway and destruction of the LED when > using a constant voltage supply and not a constant current supply. This can > be mitigated with a current limiting resistor in series, but it does > decrease overall efficiency of the system. > > Chip > AE5KA > > On Sat, Jan 7, 2017 at 8:45 AM, John Pitz wrote: > >> Actually there is a much simpler way to do this using linear 3 pin >> regulators. Take a fictional regulator that has a fixed output voltage >> of 1V. Assuming you want 15mA through your LEDs, make sure the output >> current of the voltage regulator is 15mA by placing a 67 Ohm resistor >> from the output pin to ground. The current out the VOUT of a 3 pin >> regulator will be equal to the current at the VIN of the regulator. >> Then put your string of LEDs from the "unregulated" voltage in and the >> Vin pin of your regulator. You will have to add up the expected voltage >> drops of the LEDs. and subtract that value from the unregulated Voltage >> supply. then subtract the voltage regulators output voltage, in this >> case 1V from whats left. Now, make sure that the remaining voltage is >> at least a little bit higher than the dropout voltage of the regulator. >> I have done this countless times. It should be pretty simple to use a >> POT and a resistor to dim the LEDs within a preset range, or if your >> regulator has a shutdown pin you could PWM it from your favorite >> microcontroller. >> >> You should avoid putting LEDs in series when using a simple dropping >> resistor. That scheme will seem to work well for a little while then >> you may find your LEDs failing. In my experience this doesn't work long >> term and in this scheme the LEDs fail one by one shorted. I don't think >> the voltage drop on each LED is all that constant over time and >> temperature. >> >> 73 >> KD8CIV >> >> On Sat, 2017-01-07 at 02:14 -0800, Dave Fifield wrote: >> >>> An LED is basically a fancy diode, so a linear voltage regulator to >> control >>> its brightness will not work well. >>> >>> Starting from around 2V output (say) the LED/s will be OFF. As you >> increase >>> the regulator's output voltage, somewhere around 2.5V (depends on the >> exact >>> type of LED you're using), the LED will begin to conduct forward current >> and >>> start to emit light. At this point, increasing the regulator's output >>> voltage just a tiny bit will increase the brightness of the LED a lot >> (it's >>> basically an exponential curve). So at just a couple hundred mV above the >>> voltage where the LED began to emit light, you will reach full >> brightness. >>> Any further increase in the drive voltage will merely result in the >> series >>> current-limiting resistor dissipating more heat. >>> >>> What is really needed here is a linearly-variable constant-current >> generator >>> circuit. This is a fairly simple circuit to design, usually consisting >> of a >>> voltage reference, a comparator, and a drive transistor, with some >> feedback >>> from a current sensing resistor. It will need to be designed so that it >> can >>> generate enough voltage to overcome the LED's forward voltage (Vf), and >> with >>> an output current that's variable from 0mA to around 20mA (or whatever >> the >>> LED's maximum forward current (If max) is specified at). >>> >>> Hope this helps. >>> >>> Cheers es 73, >>> Dave >>> AD6A >>> >>> -Original Message- >>> From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of >> Ron >>> D'Eau Claire >>> Sent: Friday, January 06, 2017 8:17 PM >>> To: elecraft@mailman.qth.net >>> Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position >>> recom
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
What John says is true. Over time the forward voltage drop of an LED will decrease somewhat as it ages. It isn't great, and it isn't fast, though it happens more quickly initially. The forward voltage drop decreases more dramatically in the short term with temperature - the higher the die temperature, the lower the forward voltage drop. This can result in thermal runaway and destruction of the LED when using a constant voltage supply and not a constant current supply. This can be mitigated with a current limiting resistor in series, but it does decrease overall efficiency of the system. Chip AE5KA On Sat, Jan 7, 2017 at 8:45 AM, John Pitz wrote: > Actually there is a much simpler way to do this using linear 3 pin > regulators. Take a fictional regulator that has a fixed output voltage > of 1V. Assuming you want 15mA through your LEDs, make sure the output > current of the voltage regulator is 15mA by placing a 67 Ohm resistor > from the output pin to ground. The current out the VOUT of a 3 pin > regulator will be equal to the current at the VIN of the regulator. > Then put your string of LEDs from the "unregulated" voltage in and the > Vin pin of your regulator. You will have to add up the expected voltage > drops of the LEDs. and subtract that value from the unregulated Voltage > supply. then subtract the voltage regulators output voltage, in this > case 1V from whats left. Now, make sure that the remaining voltage is > at least a little bit higher than the dropout voltage of the regulator. > I have done this countless times. It should be pretty simple to use a > POT and a resistor to dim the LEDs within a preset range, or if your > regulator has a shutdown pin you could PWM it from your favorite > microcontroller. > > You should avoid putting LEDs in series when using a simple dropping > resistor. That scheme will seem to work well for a little while then > you may find your LEDs failing. In my experience this doesn't work long > term and in this scheme the LEDs fail one by one shorted. I don't think > the voltage drop on each LED is all that constant over time and > temperature. > > 73 > KD8CIV > > On Sat, 2017-01-07 at 02:14 -0800, Dave Fifield wrote: > > > An LED is basically a fancy diode, so a linear voltage regulator to > control > > its brightness will not work well. > > > > Starting from around 2V output (say) the LED/s will be OFF. As you > increase > > the regulator's output voltage, somewhere around 2.5V (depends on the > exact > > type of LED you're using), the LED will begin to conduct forward current > and > > start to emit light. At this point, increasing the regulator's output > > voltage just a tiny bit will increase the brightness of the LED a lot > (it's > > basically an exponential curve). So at just a couple hundred mV above the > > voltage where the LED began to emit light, you will reach full > brightness. > > Any further increase in the drive voltage will merely result in the > series > > current-limiting resistor dissipating more heat. > > > > What is really needed here is a linearly-variable constant-current > generator > > circuit. This is a fairly simple circuit to design, usually consisting > of a > > voltage reference, a comparator, and a drive transistor, with some > feedback > > from a current sensing resistor. It will need to be designed so that it > can > > generate enough voltage to overcome the LED's forward voltage (Vf), and > with > > an output current that's variable from 0mA to around 20mA (or whatever > the > > LED's maximum forward current (If max) is specified at). > > > > Hope this helps. > > > > Cheers es 73, > > Dave > > AD6A > > > > -Original Message- > > From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of > Ron > > D'Eau Claire > > Sent: Friday, January 06, 2017 8:17 PM > > To: elecraft@mailman.qth.net > > Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position > > recommendation needed > > > > A linear voltage regulator is very quiet. That's just a bipolar > transistor > > passing the current with adjustable base voltage. I use them on my HB > power > > supplies for the same reason. No square switching, no RFI. > > > > 73, Ron AC7AC > > > > -Original Message- > > From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of > Bill > > Frantz > > Sent: Friday, January 6, 2017 6:07 PM > > To: elecraft@mailman.qth.net > > Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position > > re
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
Actually there is a much simpler way to do this using linear 3 pin regulators. Take a fictional regulator that has a fixed output voltage of 1V. Assuming you want 15mA through your LEDs, make sure the output current of the voltage regulator is 15mA by placing a 67 Ohm resistor from the output pin to ground. The current out the VOUT of a 3 pin regulator will be equal to the current at the VIN of the regulator. Then put your string of LEDs from the "unregulated" voltage in and the Vin pin of your regulator. You will have to add up the expected voltage drops of the LEDs. and subtract that value from the unregulated Voltage supply. then subtract the voltage regulators output voltage, in this case 1V from whats left. Now, make sure that the remaining voltage is at least a little bit higher than the dropout voltage of the regulator. I have done this countless times. It should be pretty simple to use a POT and a resistor to dim the LEDs within a preset range, or if your regulator has a shutdown pin you could PWM it from your favorite microcontroller. You should avoid putting LEDs in series when using a simple dropping resistor. That scheme will seem to work well for a little while then you may find your LEDs failing. In my experience this doesn't work long term and in this scheme the LEDs fail one by one shorted. I don't think the voltage drop on each LED is all that constant over time and temperature. 73 KD8CIV On Sat, 2017-01-07 at 02:14 -0800, Dave Fifield wrote: > An LED is basically a fancy diode, so a linear voltage regulator to control > its brightness will not work well. > > Starting from around 2V output (say) the LED/s will be OFF. As you increase > the regulator's output voltage, somewhere around 2.5V (depends on the exact > type of LED you're using), the LED will begin to conduct forward current and > start to emit light. At this point, increasing the regulator's output > voltage just a tiny bit will increase the brightness of the LED a lot (it's > basically an exponential curve). So at just a couple hundred mV above the > voltage where the LED began to emit light, you will reach full brightness. > Any further increase in the drive voltage will merely result in the series > current-limiting resistor dissipating more heat. > > What is really needed here is a linearly-variable constant-current generator > circuit. This is a fairly simple circuit to design, usually consisting of a > voltage reference, a comparator, and a drive transistor, with some feedback > from a current sensing resistor. It will need to be designed so that it can > generate enough voltage to overcome the LED's forward voltage (Vf), and with > an output current that's variable from 0mA to around 20mA (or whatever the > LED's maximum forward current (If max) is specified at). > > Hope this helps. > > Cheers es 73, > Dave > AD6A > > -Original Message- > From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ron > D'Eau Claire > Sent: Friday, January 06, 2017 8:17 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position > recommendation needed > > A linear voltage regulator is very quiet. That's just a bipolar transistor > passing the current with adjustable base voltage. I use them on my HB power > supplies for the same reason. No square switching, no RFI. > > 73, Ron AC7AC > > -Original Message- > From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bill > Frantz > Sent: Friday, January 6, 2017 6:07 PM > To: elecraft@mailman.qth.net > Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position > recommendation needed > > To avoid color shifts with dimming, most LED dimmers use Pulse Width > Modulation (PWM). PWM has the potential to generate RFI, so be careful. The > LEDs themselves should be very quiet. Using LEDs with resistors to limit the > current should also be quiet. A system that switches LEDs for brightness > control would be a safe solution, but I don't know of any commercial systems > which do this. > > On the other hand, I have not noticed a problem with the LED dimmers in my > house, so perhaps most of the problem is in the wall-wart power supply. > > 73 Bill AE6JV > > On 1/6/17 at 3:50 AM, elecraft@mailman.qth.net (Marc Veeneman via Elecraft) > wrote: > > >I mounted (dual side adhesive tape) an LED strip to the underside of an > >equipment shelf. The strip came with a 12v switcher that I ignored. I > >use my 12 volt supply. The strip was, I think, 24 inches long and has > >a dimmer that can be inserted in the power lead. No RFI. Plenty > >bright. Mine came from Amazon but there are many to c
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
There will be a switching converter on any quality make of LED lighting. The only way you avoid it is if they use a simple series dropper resistor, which is not energy efficient. LEDs are constant current devices, so there is no such thing as a 12V LED (an LED with a 12V forward voltage drop would be well into the far ultraviolet, and would still need current regulation). Professional installations would use a switching constant current supply (typically called a driver). Those for amateurs and the average building contractor would mimic tungsten bulbs by having a constant current switching regulator in each bulb. Some cheap mains operated lamps use capacitive droppers followed by rectifier and resistive current limiter. They are the type likely to be sold in one dollar stores, or on Ebay. # On 06/01/17 11:50, Marc Veeneman wrote: \ On Jan 6, 2017, at 2:00 AM, Peter D. Vouvounas wrote: I presume some of you have been through a selection process to find a usable dimmable LED desk lamp with articulating arm that does not create RFI back into your Flex on HF. I mounted (dual side adhesive tape) an LED strip to the underside of an equipment shelf. The strip came with a 12v switcher that I ignored. I use my 12 volt supply. The strip was, I think, 24 inches long and has a dimmer that can be inserted in the power lead. No RFI. Plenty bright. Mine came from Amazon but there are many to choose from these days; you can even select color temperature when you order. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
An LED is basically a fancy diode, so a linear voltage regulator to control its brightness will not work well. Starting from around 2V output (say) the LED/s will be OFF. As you increase the regulator's output voltage, somewhere around 2.5V (depends on the exact type of LED you're using), the LED will begin to conduct forward current and start to emit light. At this point, increasing the regulator's output voltage just a tiny bit will increase the brightness of the LED a lot (it's basically an exponential curve). So at just a couple hundred mV above the voltage where the LED began to emit light, you will reach full brightness. Any further increase in the drive voltage will merely result in the series current-limiting resistor dissipating more heat. What is really needed here is a linearly-variable constant-current generator circuit. This is a fairly simple circuit to design, usually consisting of a voltage reference, a comparator, and a drive transistor, with some feedback from a current sensing resistor. It will need to be designed so that it can generate enough voltage to overcome the LED's forward voltage (Vf), and with an output current that's variable from 0mA to around 20mA (or whatever the LED's maximum forward current (If max) is specified at). Hope this helps. Cheers es 73, Dave AD6A -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ron D'Eau Claire Sent: Friday, January 06, 2017 8:17 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed A linear voltage regulator is very quiet. That's just a bipolar transistor passing the current with adjustable base voltage. I use them on my HB power supplies for the same reason. No square switching, no RFI. 73, Ron AC7AC -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bill Frantz Sent: Friday, January 6, 2017 6:07 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed To avoid color shifts with dimming, most LED dimmers use Pulse Width Modulation (PWM). PWM has the potential to generate RFI, so be careful. The LEDs themselves should be very quiet. Using LEDs with resistors to limit the current should also be quiet. A system that switches LEDs for brightness control would be a safe solution, but I don't know of any commercial systems which do this. On the other hand, I have not noticed a problem with the LED dimmers in my house, so perhaps most of the problem is in the wall-wart power supply. 73 Bill AE6JV On 1/6/17 at 3:50 AM, elecraft@mailman.qth.net (Marc Veeneman via Elecraft) wrote: >I mounted (dual side adhesive tape) an LED strip to the underside of an >equipment shelf. The strip came with a 12v switcher that I ignored. I >use my 12 volt supply. The strip was, I think, 24 inches long and has >a dimmer that can be inserted in the power lead. No RFI. Plenty >bright. Mine came from Amazon but there are many to choose from these >days; you can even select color temperature when you order. --- Bill Frantz| Truth and love must prevail | Periwinkle (408)356-8506 | over lies and hate. | 16345 Englewood Ave www.pwpconsult.com | - Vaclav Havel | Los Gatos, CA 95032 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to r...@elecraft.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to d...@ad6a.com --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
A linear voltage regulator is very quiet. That's just a bipolar transistor passing the current with adjustable base voltage. I use them on my HB power supplies for the same reason. No square switching, no RFI. 73, Ron AC7AC -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bill Frantz Sent: Friday, January 6, 2017 6:07 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed To avoid color shifts with dimming, most LED dimmers use Pulse Width Modulation (PWM). PWM has the potential to generate RFI, so be careful. The LEDs themselves should be very quiet. Using LEDs with resistors to limit the current should also be quiet. A system that switches LEDs for brightness control would be a safe solution, but I don't know of any commercial systems which do this. On the other hand, I have not noticed a problem with the LED dimmers in my house, so perhaps most of the problem is in the wall-wart power supply. 73 Bill AE6JV On 1/6/17 at 3:50 AM, elecraft@mailman.qth.net (Marc Veeneman via Elecraft) wrote: >I mounted (dual side adhesive tape) an LED strip to the underside of an >equipment shelf. The strip came with a 12v switcher that I ignored. I >use my 12 volt supply. The strip was, I think, 24 inches long and has >a dimmer that can be inserted in the power lead. No RFI. Plenty >bright. Mine came from Amazon but there are many to choose from these >days; you can even select color temperature when you order. --- Bill Frantz| Truth and love must prevail | Periwinkle (408)356-8506 | over lies and hate. | 16345 Englewood Ave www.pwpconsult.com | - Vaclav Havel | Los Gatos, CA 95032 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to r...@elecraft.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
To avoid color shifts with dimming, most LED dimmers use Pulse Width Modulation (PWM). PWM has the potential to generate RFI, so be careful. The LEDs themselves should be very quiet. Using LEDs with resistors to limit the current should also be quiet. A system that switches LEDs for brightness control would be a safe solution, but I don't know of any commercial systems which do this. On the other hand, I have not noticed a problem with the LED dimmers in my house, so perhaps most of the problem is in the wall-wart power supply. 73 Bill AE6JV On 1/6/17 at 3:50 AM, elecraft@mailman.qth.net (Marc Veeneman via Elecraft) wrote: I mounted (dual side adhesive tape) an LED strip to the underside of an equipment shelf. The strip came with a 12v switcher that I ignored. I use my 12 volt supply. The strip was, I think, 24 inches long and has a dimmer that can be inserted in the power lead. No RFI. Plenty bright. Mine came from Amazon but there are many to choose from these days; you can even select color temperature when you order. --- Bill Frantz| Truth and love must prevail | Periwinkle (408)356-8506 | over lies and hate. | 16345 Englewood Ave www.pwpconsult.com | - Vaclav Havel | Los Gatos, CA 95032 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
On Fri,1/6/2017 7:24 AM, Craig Smith wrote: Have a look at this one: I'm using LED strip lights from Wired Communications. Discovered them several years ago -- they sell at hamfests on the west coast. Do NOT use their power supplies. But their strips work great on a wide range of DC voltages. I run them from the 12V system in my shack. Four of their strips light my shack for normal operation, current draw is about 1.2 A. In general, it's dimmers and power supplies that are noisy, not LEDs. Of course there are exceptions. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
Greetings Peter … Have a look at this one: https://www.amazon.com/Dimmable-Stoog-Brightness-Rechargeable-Adjustable/dp/B01CSHZ99Y/ref=sr_1_10?s=home-garden&ie=UTF8&qid=1483715928&sr=1-10&keywords=usb+led+desk+lamp I’m not claiming this is the highest quality lamp ever made. I also do not currently have a way of assessing the EMI situation with your setup. However, it is an amazingly versatile lamp and well worth the $13 price! Even if you select something else, you may want to have one of these around for other purposes. Some of the things I like about it: Very small and light and easily moved around for the task at hand. Convient recharge from any USB port. 3 selectable light intensities. Very long time between recharges. I use mine fairly intermittently, but get 2 or 3 months usage on a charge. For $13, it can be considered a throw-away item if you don’t end up liking it. 73 CraigAC0DS __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
I've used this one for over a year, and pleased with it. My wire antennas are only about 25 ft away and no noise issues: https://www.amazon.com/gp/product/B00KSQ8ZNA/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1 Barry W2UP -- View this message in context: http://elecraft.365791.n2.nabble.com/Dimmable-LED-desk-lamp-for-operating-position-recommendation-needed-tp7625496p7625500.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed
\ > On Jan 6, 2017, at 2:00 AM, Peter D. Vouvounas wrote: > > I presume some of you have been through a selection process to find a usable > dimmable LED desk lamp with articulating arm that does not create RFI back > into your Flex on HF. > > I mounted (dual side adhesive tape) an LED strip to the underside of an equipment shelf. The strip came with a 12v switcher that I ignored. I use my 12 volt supply. The strip was, I think, 24 inches long and has a dimmer that can be inserted in the power lead. No RFI. Plenty bright. Mine came from Amazon but there are many to choose from these days; you can even select color temperature when you order. -- Marc W8SDG __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Dimmable LED desk lamp for operating position recommendation needed
I presume some of you have been through a selection process to find a usable dimmable LED desk lamp with articulating arm that does not create RFI back into your Flex on HF. My current desk lamp (Halogen with mini bulb dimmable) makes a great deal of noise in the 80 meter band and I'd like to replace it. Hard to operate without a lamp. My wife calls my home office / shack the cave. Often I need a dimmed light in the cave hihi. Thank for any help. PeterV WB3FSR on the Jersey Shore __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
