whiteboard lights

Where are the lights, upper left?

Right, the two black things kluged into the big fixture. The high angle prevents glare.

I ran a white #22 twisted pair to the wart, hidden by the existing conduit. We expect some electrical inspectors soon, and I don't want them to notice much.

Maybe I should paint the lights white too.

I don't throw computers off the roof like Bob Pease did, but I do like to draw on paper or whiteboards.

Doesn't look well-placed from the ergonomic PoV, John. Unless you're left- handed - or some kind of contortionist. Does that old Keithley meter still get some use?

I use this style of lamp for lab/bench lighting, compact/futuristic and very bright:

This one would work good for an over-whiteboard lamp:

The whiteboard is optimally placed for me to sit at the bench, measure stuff, and draw/plot with my right hand.

I do use the Keithley when I'm working with picoamp stuff, and I use the big ole Tek sampling scope when I'm doing picosecond stuff.

Hmm I'll have to get some. They would be perfect when I'm testing a diode laser. The room lights get into the photodiodes and are always an 'issue'. (I had some LED's for auto's running on a lab power supply, but I over- voltaged them.. oops.)

George H.

A 'scope without a Lissajous pattern? Isn't that against the rules?

Cheers

That whiteboard is super glossy, and has a faint grid line pattern that's great for guiding orthogonal lines, or for graph grids. But it really reflects any background light. So high-angle immumination is mandatory. The opposite wall is an enormous window, so I can easily get fuzzy images of city busses or the freeway foliage superimposed on my pics. There is one place I can stand to get a good pic.

I often send whiteboard pics to customers, sometimes in proposals, so they need to be not too very ratty.

I've seen whiteboards that have built-in scanners, but every one was broken.

I used these:

Each makes a nice oval pattern so the pair illuminates the whiteboard very nicely. I use a 12 volt wart to power the pair. I threw away the spikes and loosely bolted them to a flat aluminum plate, so they can be aimed in yaw and pitch.

We don't do sine waves. Our scopes only display pulses.

There are glare reduction filters available for those shoplight style fixtures you have.

Yeah, the draftsman's standard of light from over the left shoulder (for right-handers) is another way to accomodate/control reflection.

For a bright window, either blackout shades, or a motorized screen (like a projection screen) can be useful. Sometimes, tilting the board helps, too (you can tilt, snap the photo, then straighten it).

One could also fit a camera with polarizer, and illuminate with a cross-polarized flash (preferably diffused); that makes colors especially vivid.

For good artistic work, computer displays with color calibrations are employed, by folk wearing dark shirts... no joke.

Dang.. I should have asked you to look at the led's with a photodiode. The output is a ~40kHz sine wave. Not full modulation, but just about! I'll have to hack something... (which takes time)

George H.

I was stopped at a red light and noticed the wheels of the cars driving past. I saw a stroboscopic spoke effect from my headlights.

So I want to make a phototransistor connected to an amp and a speaker and drive around listening to street lights, car lights, house lights. Maybe add a sampler, essentially mix with a spectral comb, to bring down the supersonic stuff.

Yeah I'm guessing mostly the frequency would be above what our old ears can hear.

And that doesn't solve my problem at all. :^)

Can I make the inductor equivalent of a cap multiplier to filter a current source? (I might be thinking about that worng.)

George H.

Neat. Sometimes the cheap stuff is really efficient. I'd probably try to mount the lights closer above so the body of the person sketching on the board won't throw a shadow.

What is that analog meter on the top shelf? A tube multimeter?

Sure. Lift the ground end of the capacitor and connect it to the emitter.

Cheers

Phil Hobbs