I'm designing a nightstand glasses tray, because its hard to find glasses when they blend in to the dresser. 'course having a 3d printer and a flashlight obsession, I decided to print it in white so the glasses will stand out, and then took it a step further and want to design in some super long running LED's (think AUX lights on a "Hank Light" in white) so the glasses will stand out even with the lights off. Any thoughts on how to make this not stupid huge? Could do 18650's but that'll increase the size of the tray by 50%, hoping for AA's or smaller. I'll be using rechargeable but would like it to last at least a few months between charges...
Ultra low brightness led/driver for nightstand 3d printed glasses tray?
- Thread starter Fird
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Me, I'd buy a cheap solar garden light and rip out the guts. Find a way to integrate the solar charging, and don't worry about charging the batteries.
For this application, you really want a very low drive current on your LEDs. Assuming 5mA draw and direct drive (with a current-limiting resistor), you're looking at about 140 hours of operation off a 700maH 14500 cell. Dropping the current can extend that, but you aren't going to get reasonable output at much lower drive currents. The other option is to increase the battery capacity. An 18650 will get you ~4x the run time of a 14500, or you could go with 3x NiMH AA (to get the current up) for about 3x the run time. But if you really want months of operation, you're looking at both more battery and lower drive current (and are starting to hit up against the lower limits of reasonable current for both the LEDs and the batteries).
For this application, you really want a very low drive current on your LEDs. Assuming 5mA draw and direct drive (with a current-limiting resistor), you're looking at about 140 hours of operation off a 700maH 14500 cell. Dropping the current can extend that, but you aren't going to get reasonable output at much lower drive currents. The other option is to increase the battery capacity. An 18650 will get you ~4x the run time of a 14500, or you could go with 3x NiMH AA (to get the current up) for about 3x the run time. But if you really want months of operation, you're looking at both more battery and lower drive current (and are starting to hit up against the lower limits of reasonable current for both the LEDs and the batteries).
Dave_H
Flashlight Enthusiast
I've been experimenting with low-level low-cost LED devices for nightlight use, and amazed how long some of these run even with cells which are not usable in other higher-drain devices i.e. my supply of "recovered" cells.
Depends on size of platform and light distribution, brightness and colour of light you want. Something as simple as a dollar-store string of LEDs running from 2-3AA might work.
You might also consider LED strips. One example is 3-foot RGB which runs from 5v USB. It could be cut shorter. IR remote in this case may be overkill. Others can run directly from 5v or 12v; you can control brightness by applied voltage and/or series resistance.
Dave
Depends on size of platform and light distribution, brightness and colour of light you want. Something as simple as a dollar-store string of LEDs running from 2-3AA might work.
You might also consider LED strips. One example is 3-foot RGB which runs from 5v USB. It could be cut shorter. IR remote in this case may be overkill. Others can run directly from 5v or 12v; you can control brightness by applied voltage and/or series resistance.
Dave
Dave_H
Flashlight Enthusiast
Is the tray translucent or opaque white? Could you light it from underneath? Low-cost idea would be string of "micro-dot" LEDs typically 10-20 which run from 2AA, at some dollar stores for only a couple of bucks usually. Commonly available in white (usually warm) and some other colours, around this time orange or purple for Hallowe'en if you like!
Dave
Dave
I bought a glow in the dark frisbee years ago for my glasses at night. I also have GITD trays from County Comm
JustAnOldFashionedLEDGuy
Enlightened
- Joined
- Apr 13, 2020
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I like the solar idea. 5mA into a white LED is probably more than you want in a bedroom. That is 15mW, or about 1-1.5 lumens with a white LED. That is surprisingly a lot. I think you would find them with 1/10th that much. Light from above so it does not bother you. A modern 30-60 degree 5mm LED, as warm as you can get it.
Dave_H
Flashlight Enthusiast
Yes, solar garden light can be a cheap source of LED and driver for low levels even without using the solar panel to charge i.e. use a primary cell. I do this all the time. Some will run for several nights on a used alkaline/zinc-carbon AA or AAA or NiCd/NiMH which can be recharged separately.
The little boost drivers are interesting. To increase current and brightness (within practical limit), inductor is reduced. It is easy to connect another in parallel versus cutting or desoldering existing part. I tried this with a $1.25 solar spot from Dollar Tree. To decrease brightness, cut or unsoldering is needed to change the inductor or insert another in series. I have not tried this yet.
Not all solar lights have a switch, or easy access to the cell. Better ones for this purpose use a battery holder with hatch. Some have cell soldered right in and require more disassembly.
Dave
The little boost drivers are interesting. To increase current and brightness (within practical limit), inductor is reduced. It is easy to connect another in parallel versus cutting or desoldering existing part. I tried this with a $1.25 solar spot from Dollar Tree. To decrease brightness, cut or unsoldering is needed to change the inductor or insert another in series. I have not tried this yet.
Not all solar lights have a switch, or easy access to the cell. Better ones for this purpose use a battery holder with hatch. Some have cell soldered right in and require more disassembly.
Dave
