Just curious to know what other amplifier builders think about the various illuminated push button power switch options.
What LED color(s) do you prefer and why?
What action do you prefer, momentary or latching?
I've noticed a lot of manufacturers using blue, but that's not great for night time use IMO.
What LED color(s) do you prefer and why?
What action do you prefer, momentary or latching?
I've noticed a lot of manufacturers using blue, but that's not great for night time use IMO.
I prefer orange or green. If you dim it very low, then it isn't too distracting but you can still see the different between on and off. Most equipment LEDs are far too bright.
I prefer white and orange, just like them more than others. And couple of months ago i moved to using momentary and relay circuit to turn on the device, unecessary but i like it atm. If you have a need for delay in your device, momentary and a delay/relay circuit is an elegant solution, thats about it as an advantage (oh and since it's not a "hard" contact, momentary tends to last longer). Con is that you have to supply that circuit constantly.
Accepted practicе is green light for ON or when something is working OK, red light for something wrong or when attention is required. But orange/amber is pleasant color and can be used too. Blue is irritant.
One important design consideration: majority of color LEDs have tinted plastic housing in the same color of the LED emitting light - which on a bright day (or bright room illumination) can not be distinguished between ON and OFF. Is it ON or OFF? Hard to tell, unless LED is really bright - which is irritant. So, use color LED with milky-white/opal/frosted plastic housing - when it is ON, it will be very noticeable because color will be changed.
Momentary or latching? Depends on further action (relay circuit, etc). For simple ON/OFF latching is more ergonomic.
One important design consideration: majority of color LEDs have tinted plastic housing in the same color of the LED emitting light - which on a bright day (or bright room illumination) can not be distinguished between ON and OFF. Is it ON or OFF? Hard to tell, unless LED is really bright - which is irritant. So, use color LED with milky-white/opal/frosted plastic housing - when it is ON, it will be very noticeable because color will be changed.
Momentary or latching? Depends on further action (relay circuit, etc). For simple ON/OFF latching is more ergonomic.
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Can't comment on the switching action but for the LED color I do prefer blue over the traditional colors.
On recent builds I have included a brightness adjustment pot which makes it much easier to get that right.
On recent builds I have included a brightness adjustment pot which makes it much easier to get that right.
Agree Amber makes sense with tubes, or looks right
The classic light for tube instrument amps was Red " jewel" style.
My old radios were actual real white incandescent. Nothing beats that.
Any additional color was the dial art. Something that should come back.
Everything looks like a 90's DVD player now...Boring
The classic light for tube instrument amps was Red " jewel" style.
My old radios were actual real white incandescent. Nothing beats that.
Any additional color was the dial art. Something that should come back.
Everything looks like a 90's DVD player now...Boring
Momentary action power switch makes sense to me only when you want to employ remote or central switching.
I think that incandescent bulb is just the ideal you can only come close to with LEDs. I also think that naked LEDs sticking out of the panel are maybe ok on laboratory instrument, but not on the serious living room accessory. Similarly with typical illuminated switch, the edges of the light are usually sharp and therefore not really very nice.
But in the end it's up the taste.
I think that incandescent bulb is just the ideal you can only come close to with LEDs. I also think that naked LEDs sticking out of the panel are maybe ok on laboratory instrument, but not on the serious living room accessory. Similarly with typical illuminated switch, the edges of the light are usually sharp and therefore not really very nice.
But in the end it's up the taste.
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I prefer red for standby and green for on. I dial the intensity way down so the indicator light isn't blinding at night.
I suppose those who are colour deficient would prefer red and blue or at least something other than red/green so they can tell the difference between standby and on.
For the switch action I prefer momentary switches. To me, such switches just give a cleaner look.
E-Switch is my preferred switch manufacturer: https://www.e-switch.com/. They're decidedly not cheap, but they look nice and I have yet to have one fail.
Another favourite of mine is how Apple handled the indicator light on the first aluminum Mac mini. I don't know if it still the case. But anyway. The light was a single pinpoint white LED. When the LED was off it blended into the aluminum surface. This light was off when the computer was active. Brilliant! Why would I need an indicator to tell me that the computer is on when the monitor shows that it is? In standby the LED would gently fade in/out. And I think in sleep the LED would be off, but I don't remember.
I'm not sure I'd want a blinking or in/out fading LED in an audio setup, but it certainly worked well for the computer and it didn't take long for other manufacturers to copy that with varying degrees of success.
Tom
I suppose those who are colour deficient would prefer red and blue or at least something other than red/green so they can tell the difference between standby and on.
For the switch action I prefer momentary switches. To me, such switches just give a cleaner look.
E-Switch is my preferred switch manufacturer: https://www.e-switch.com/. They're decidedly not cheap, but they look nice and I have yet to have one fail.
Another favourite of mine is how Apple handled the indicator light on the first aluminum Mac mini. I don't know if it still the case. But anyway. The light was a single pinpoint white LED. When the LED was off it blended into the aluminum surface. This light was off when the computer was active. Brilliant! Why would I need an indicator to tell me that the computer is on when the monitor shows that it is? In standby the LED would gently fade in/out. And I think in sleep the LED would be off, but I don't remember.
I'm not sure I'd want a blinking or in/out fading LED in an audio setup, but it certainly worked well for the computer and it didn't take long for other manufacturers to copy that with varying degrees of success.
Tom
Just adding precision: Orange and cyan are hues. The saturation is how much white is blended in with a particular hue.
Tom
Same as Sonce. Diffuse green or diffuse white at lowest possible current for power on, red for stand-by (and for errors) and blue for nothing as it is a terrible color in a dim lit room and blue LEDs are way too bright. I recall reading some people have trouble focussing eyes with blue light just like me. Seems a kind of loss of depth in sight. My habit is to replace blue LEDs at once for either green or white ones.
Momentary or latching is more difficult. Latching switches often indicate stuff to be powered on by a mechanical difference. This of course counts especially for rocker and rotary switches but less for push button switches. With push button switches both types exist in the same physical shape. This AMB circuit can be of great help when only a momentary version is available. It adds bicolor option and overtemperature protection too:
https://www.amb.org/audio/epsilon24/
Momentary or latching is more difficult. Latching switches often indicate stuff to be powered on by a mechanical difference. This of course counts especially for rocker and rotary switches but less for push button switches. With push button switches both types exist in the same physical shape. This AMB circuit can be of great help when only a momentary version is available. It adds bicolor option and overtemperature protection too:
https://www.amb.org/audio/epsilon24/
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I agree. To me, blue LEDs always appear a bit out of focus which makes them even more distracting.
I seem to recall that humans have much fewer short-wave cones than medium-wave and long-wave ones. I.e., we have lower visual acuity for short-wave light, i.e., blue light. That could be an explanation.
Tom
I hate blue LEDs in equipment. My next door neighbor has exclusively blue exterior lighting along with lots of blue lights he uses in the late evening inside his house. He has trouble sleeping for some reason.
Companies are desperate to show that the new model is different in some way and went away from the old red LEDs in a constant progression using whatever LED color was newly available over the years. So now we are stuck with blue. Being some what color blind, the red/green combo LED is my second least favorite.
I try to buy equipment that has red or orange power on indictors if possible and I put a piece of black tape over the blue LEDs.
Companies are desperate to show that the new model is different in some way and went away from the old red LEDs in a constant progression using whatever LED color was newly available over the years. So now we are stuck with blue. Being some what color blind, the red/green combo LED is my second least favorite.
I try to buy equipment that has red or orange power on indictors if possible and I put a piece of black tape over the blue LEDs.
Only if there are green and red LEDs below and above that yellow LED. 🙂
Once you mentioned it, I am getting better idea:
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I like amber and yellow: visible but not too attention-grabbing. It took me a while to find a large diameter ring light push button with more than one pole: https://www.amazon.com/dp/B0CNYZ56ZG . It's also nice that it has a plug-in harness. I'm sure e-switch (mentioned by Tom) must have something just like it in their program, but at first glance they stop at 28mm cutout, and I didn't see a double pole option? Digikey selection also gets quite thin above 30mm in stainless steel. Using a momentary switch + relay combination probably opens up more choices.
I just throw a micro controller at it. A small micro doesn't cost much more than the driver transistor for the relay anyway. 🙂 But you could also use a D flip-flop as a toggle flop and control the relay that way.
Then, of course, I put a bunch of other features in the micro controller as well. LED dimmers, child lock, etc.
Tom
Thanks for all your responses. I agree, momentary action is best if you are controlling the power with a remote control, latching otherwise. With regards to color, the only real consensus here seems to be to avoid blue. I was surprised about the popularity of green, but it does go surprisingly well with a silver front panel. Red LED's used to be the only ones available, so early equipment would have used those purely because there was no other choice.
I asked google Gemini about LED color and required it to give scientific justification. It gave an excellent answer which I'll put here for reference. It's recommendation was to use red or amber color LED's. Please see below:
I also asked it to consider color blind people, and then it came up with a different recommendation, blue or white. Green/red confusion is pretty common, which is why they changed the electrical wiring standards.
I've got an alarm clock with white display. It has 3 levels of brightness and an off setting. On the lowest setting, it's barely visible. But I still find that annoying at night when I want to sleep, so I just turn it off. So it seems even tiny amounts of white light are a problem in dark rooms if you want to sleep. Maybe the moral of the story is don't put an amplifier in the bedroom 🙂
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When choosing the best color for a power switch LED, several scientific factors should be considered, including human eye sensitivity, energy efficiency, and potential impact on sleep cycles.
The Best Color: Red or Amber
Based on scientific understanding, red or amber (orange-yellow) is generally the best color for a power switch LED, especially in environments where human presence or sleep quality is a concern.
Scientific Justification:
For a power switch LED, particularly one that might be visible in a dark room, red or amber is the superior choice. This is primarily due to its minimal impact on human night vision and sleep-wake cycles, ensuring it provides a clear indicator without being disruptive.
Challenges with Red and Amber for Color Blindness:
The most common forms of color blindness are red-green deficiencies (protanomaly/protanopia and deuteranomaly/deuteranopia), affecting a significant portion of the male population (around 8%).
When taking color blindness into account, blue or a neutral white (ideally with a lower color temperature to minimize blue light content if sleep is a concern) becomes a more universally accessible choice for a power switch LED.
I asked google Gemini about LED color and required it to give scientific justification. It gave an excellent answer which I'll put here for reference. It's recommendation was to use red or amber color LED's. Please see below:
I also asked it to consider color blind people, and then it came up with a different recommendation, blue or white. Green/red confusion is pretty common, which is why they changed the electrical wiring standards.
I've got an alarm clock with white display. It has 3 levels of brightness and an off setting. On the lowest setting, it's barely visible. But I still find that annoying at night when I want to sleep, so I just turn it off. So it seems even tiny amounts of white light are a problem in dark rooms if you want to sleep. Maybe the moral of the story is don't put an amplifier in the bedroom 🙂
=========
When choosing the best color for a power switch LED, several scientific factors should be considered, including human eye sensitivity, energy efficiency, and potential impact on sleep cycles.
The Best Color: Red or Amber
Based on scientific understanding, red or amber (orange-yellow) is generally the best color for a power switch LED, especially in environments where human presence or sleep quality is a concern.
Scientific Justification:
- Human Eye Sensitivity (Scotopic Vision):
- The human eye has two types of photoreceptors: rods and cones. Cones are responsible for color vision in bright light (photopic vision), while rods are responsible for vision in dim light (scotopic vision).
- In low-light conditions, our vision primarily relies on rods, which are less sensitive to red light compared to other colors. The peak sensitivity for scotopic vision is around 507 nm (blue-green).
- This means a red or amber LED will appear less intensely bright in a dark room, minimizing disturbance to adaptation to darkness and night vision. This is why red light is often used in observatories or for reading maps at night without affecting night vision.
- Impact on Sleep (Melatonin Suppression):
- Exposure to certain wavelengths of light, particularly blue light (450-500 nm), significantly suppresses the production of melatonin, the hormone that regulates our sleep-wake cycle (circadian rhythm).
- Blue and even green light (around 450-550 nm) can trick the brain into thinking it's still daytime, making it harder to fall asleep and reducing sleep quality.
- Red light, with its longer wavelengths (610-760 nm), has the least impact on melatonin production. Therefore, a red or amber power switch LED is less likely to disrupt sleep, making it ideal for bedrooms or other areas where sleep quality is important.
- Energy Efficiency (Minor Factor for a Small LED):
- While blue LEDs can be more energy-efficient for general lighting applications, the power consumption of a tiny power switch LED is negligible regardless of its color.
- However, if we consider the energy required for the LED chip itself, shorter wavelengths (like blue) generally require higher operating voltages and can be more energy-intensive to produce the same luminous flux compared to longer wavelengths (like red), though advancements in LED technology have made this difference less significant for small indicator lights. For a power switch LED, the primary concern isn't maximizing lumen output for illumination, but rather providing a subtle indicator.
- Minimizing Light Pollution (Less Relevant for Indoor Switches):
- While blue-rich outdoor lighting significantly contributes to sky glow and light pollution, a small indoor power switch LED has a negligible impact on this. However, the principle of minimizing blue light at night for biological reasons still applies indoors.
- Blue: Highly alerting and melatonin-suppressing. Not ideal for a power switch LED in a bedroom or any area where minimizing light disturbance is important.
- Green: Also has a significant impact on melatonin suppression, though generally less than blue light. Can still be alerting.
- White (Cool or Daylight): These often contain a significant blue light component, making them problematic for sleep and potentially harsh in dark environments.
- White (Warm): Better than cool white, but still contains some blue light.
For a power switch LED, particularly one that might be visible in a dark room, red or amber is the superior choice. This is primarily due to its minimal impact on human night vision and sleep-wake cycles, ensuring it provides a clear indicator without being disruptive.
Challenges with Red and Amber for Color Blindness:
The most common forms of color blindness are red-green deficiencies (protanomaly/protanopia and deuteranomaly/deuteranopia), affecting a significant portion of the male population (around 8%).
- Red-Green Confusion: For individuals with these conditions, red and green can appear very similar, often as shades of brown or muted colors. This means that a red or amber LED, while great for normal vision, might be indistinguishable from a green LED or even off for someone with red-green color blindness.
- Brightness Differences: While red light is often dim for protanopes (red-weakness), deuteranopes (green-weakness) don't have the same brightness issues, but still confuse red and green.
When taking color blindness into account, blue or a neutral white (ideally with a lower color temperature to minimize blue light content if sleep is a concern) becomes a more universally accessible choice for a power switch LED.
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