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Originally, the surface-mount LED ring light was designed to provide portable light for a wireless video camera. Perhaps I’m going to mount it to a robot that will explore duct work?
A side view and rear view of a surface-mount LED miniature ring light attached to a wireless video camera.
The thickness of the ring light board turned out to be excellent! If I had used standard 1 3/4 diameter thru-hole LEDs, the LEDs would have stuck out beyond the front of the camera lens. It is likely that light would have directly entered the lens and altered the image.
Admittedly, the sides of the surface-mount LED ring light stick out a bit. It would be possible to design a narrower ring light by using fewer LEDs and reorienting each LED at an angle parallel to the perimeter.
Video images captured without any external lighting, using only a miniature LED ring light from 1 foot and 3.5 feet away respectively.
I’m somewhat disappointed in the quality of the video images. The video camera is not of particular high quality and the image is delivered wirelessly, which results in added noise. But, remember that these pictures were taken without any other lighting (in an otherwise completely dark room).
At 1 foot, the colors are acceptable and the image is clear, although there are hot spots (not unexpected from a reflective surface). At 3.5 feet, the colors start to wash out and the image is grainy, demonstrating the limits of this light source.
A ring light can really improve the visibility of small parts during circuit inspection with a magnifying glass. You can see inside the nooks and crannies, as well as in-between cramped electronic components. It’s easier to read tiny part numbers with extra light.
10x Folding Loupe Magnifier
An inexpensive 10-times magnification folding loupe magnifier can be purchased from Electronic Goldmine for only $1.99 (part #G15892). It is perfectly adequate for most work.
Although the folding cover is useful to protect the lens from damage, the cover needs to be removed to add a ring light.
The plastic loupe housing has raised areas that need to be milled flat before mounting the ring light.
If the LED ring light had been designed for the dimensions of the magnifying glass, it might be possible to tap the rivet hole for a screw. But, attempting to tap screw holes at the existing ring light dimensions would likely damage the integrity of the loupe’s plastic body. The screws might even press against the lens, resulting in distortion.
Instead, it seems like a better idea to glue new mounting hardware to the loupe body for attaching the ring light. That means that the raised portions on the bottom of the magnifying glass housing need to be milled flat for a reliable fit.
Left: Placing bolts and nuts on the ring light. Right: Nuts super glued in place on the magnifying glass case.
Rather than spend a lot of time machining a special adapter mounting plate for a $2 magnifier, I decided to go with a quicker method. Off-the-shelf stainless nuts can act like ready-made tapped holes if they’re glued onto the loupe housing.
To position the nuts accurately for gluing, they are first screwed onto the ring light. The end of the screw must not be the same length or longer than the back of the nut. Otherwise, the nut will not sit flush against the magnifying glass housing and the screw tip may mistakenly receive some of the glue.
Glue was careful placed on the face of each nut while they were on the PCB. The PCB was then lined up and pressed against the magnifying glass frame. They were held together for a minute or two.
I used Poly-Zap Glue (cyanoacrylate) thinking that it was generic super glue. It doesn’t list stainless steel or any metals as recommended bondable materials. Yet, it seems to work just fine.
After a few minutes, the screws were withdrawn. The ring light can now be attached or removed from the loupe magnifier as desired.
Lighted magnifier demonstrating its effectiveness on a PCB.
In my opinion, the ring light works better on the lighted magnifier than it does on the video camera. In fact, in a normally lit room, the current can be turned down to as little as 10 mA (total) to eliminate bright reflections but still enhance close-up lighting.
All in all, the surface-mount LED ring light project was a success. I’m very pleased with the qualities of the LEDs and the small size of the rounded PCB. The light distribution is even and the circuit board never seems to get very hot.
The LED color is a bit bluish. It might be an improvement to mix in a few warmer-color LEDs, even if they are slightly more expensive.
