Martin Schmidt

I would suggest ink-jet printable transparency film, though it would result in partially-transparent C-notes. Ryonet WaterProof Inkjet Film might work. Transparency would actually be advantageous because the note would be visible from either side without the registration problems involved with printing two sides.

Years ago I worked in a commercial photo lab and back then I would have made them by photographing a real C-note on slide film. This could still be done if you can still find a place that processes slide film. The result would be waterproof but they might tend to stick together (unless the glycerin prevents that). I don't know how the emulsion might behave under long-term immersion, though.

Using multiple 2N3906 small-signal transistors in parallel to switch a large amount of current in your charger is not really a good design. The process you describe to determine the number of transistors needed overheats some of them (as you state) and this stresses them and can lead to a failure later on. Since you use only one more transistor than is needed to keep them from overheating, if one of the stressed transistors does fail later the others will quickly overheat and another one will fail even more quickly, and this domino effect will then burn them all out in rapid succession.

A better design would be to use a single power transistor such as a TIP125. This kind of transistor is designed for applications such as this. It's also helpful to determine in advance (by experimentation if necessary) how much current your coil draws and then read the datasheets of various transistors to determine the best one for the job. Googling "transistor datasheets" will turn up numerous websites that can help you.

Hi, Marc! The link to your Flickr set is missing from bullet 2. I tried searching Flickr so I could add the link but couldn't find your set.

This reminds me of the time I was involved in a local theater production of Little Shop of Horrors. At the cast party, along with all the other food items we had a big plate of salad for the guests to feast from. In the center of the plate was a replica of the "Audrey II" plant made from a medium-sized watermelon with a jagged-toothed mouth cut in it. The "plant" was surrounded by fruit and other salad items and, of course, had a sign stuck behind it that said, "Feed me!"

Because bokeh is created in the areas of the photo that are outside the field of focus, longer lenses should actually work better for this since by their nature they have less depth of field than shorter lenses do.

Wonder if there would be an easy way of constructing hydraulic actuators out of, say, PVC pipe and O-rings, and using some sort of lightweight reinforced resin casting of the paver, hinged to the basin, as a cover. The idea is that the water pressure would lift the cover when the sprinkler was turned on and the cover would fall back into place when the water was turned off.

Although perhaps I'm over-engineering it...

That's an ingenious idea! Well done!

Step 3 refers to the cork sections having a "flat" and a "slanted" side, but there is no previous step that mentions the corks being cut on a slant.

In bullet 4, I think perhaps the author means to use just the hook side of the Velcro, not the loop side.