LED board, dremel'ed

You get nice solder joints. Are you using a stereo microscope? Although the dremel cutting is shakey, it is just cosmetic. Harbor Freight sells a flexible shaft machine for low cost which works well. I suppose you could create a "micro-gouge" which is a tool steel scoop to be run along a straight edge. I have carbide versions used to part on a lathe. But is the trouble worth it?

jb

Scribing/carving 50 thou lines out of copper clad is hard?

A normal ("fine", but not really) Sharpie is smaller than that. You're just bad.

I'd say "what's wrong with kids these days", but theoretically, you should have more experience than I.

And before you use your standard tired "well what can YOU do" retort, ... you know, I won't even give you the pleasure of an example. So there.

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

Yes, a Mantis with a 4x lens.

Some sort of guide or pantograph would be good, but the freehand is kinda artistic and very fast.

It's a Chinois copy of the US-made original by "Foredom"

Best regards, Spehro Pefhany

Yes, I have looked at the Foredom in detail. The HF one s a great buy, if you condition the bearings when it's new. I have one for small work, and another connected to a gang tool cnc lathe. The other end of the flex shaft is connected to their 3/4 in. hand drill. ($30), also a good buy. The set up has loads of torque at fairly high rpm, just like a drill does. I also have a HF air drill mounted on the slide table, controlled by an air solenoid valve. This turns at 25k, but like air, loads down for any drill >3mm.

I do deep hole drilling wth the lathe, and have modified a HF airless paint sprayer to deliver 4000 psi coolant into a coolant through drill, typically

Some of the HF stuff is not junk, and they have reviews online.

jb

Wow. I'd be happy if I could do as well as he did.

Ed

Yes,,the exact same parts shrink as our eyes get older.

On a sunny day (Wed, 12 Mar 2014 21:52:48 -0800) it happened Robert Baer wrote in :

But when I was young the tube sockets were so big.

Are those handheld, or some big machine? Air powered?

The Mantis fixes the optical problem nicely. But the parts are hard to hand place to a few mils acuracy. They are so light that they stick to tweezers. Indexing is often invisible, I guess because the mfrs assume reel-fed pnp machines. Desoldering can be awful.

And they *always* land upside down.

Here's the thing in action.

What I'm going to do is go through (up to) 250 TO5 photodiodes and pick 10 that are in the center of the sensitivity distribution, and archive them as "gold" references, for future normalization of production photodetectors.

The cute little Thorlabs brick is just a diode mount and a 12 volt battery; we'll use a Fluke DVM to measure the PD currents, about 5 uA. I'll use my old Keithley electrometer to measure dark current, something like 60 pA.

The trick is to make sure the illumination is very constant and flat. Putting a piece of frosty mylar in the plane of the photodiode, we were seeing a distinctive Maltese Cross sort of structure in the center of a diffuse field, apparently focussing effects from the walls of the machined tube. A lot of bead blasting fixed that.

Wow - impressive. What does this device do? (if you can say) Why are you using smd leds? Why is the flange at the bottom of the snout milled rather than turned? jb

The end product is an optical/electrical converter. It's a round tube that will drop into the top of that fixture to get tested. We will also occasionally plug in one of the "gold" photodiodes to make sure that the illumination level is constant.

One of my guys tested over 20 LEDs to find a part that makes nearly constant light vs temperature, and has good fast pulse response. Green LEDs seem to have the lowest temperature coeficients; reds are terrible. And lots of LEDs make weird light waveforms if you pulse them. These happen to be good in both respects. Too bad they're 0603s.

Dunno, my mechanical guy made it, on the Tormach n/c mill. There are some bosses under the PCB, stuff you can't do on a lathe. It's a lot fancier than I'd anticipated (I expected just a round puck) but he enjoys doing stuff like this.

Optics is tricky. We can measure electrical stuff to parts per million (frequency, parts per billion) but 1% is a challenge to hold for light intensity.

When I was a kid, I assembled power components with pliers and screwdrivers. Now, a 12W LED driver is so small that I need a high power magnifier to see if I etched the traces properly.

Same principle as PB&J on toast landing sticky side down. On needs to find out how to integrate a cat in such things..

Next try some 01005s.

I used to build stuff from old TV sets and military surplus electronics. Kids can't do that any more. So they write code.

They can buy parts from Digikey and build real circuits, and some do, but not enough.

Every kid should own a pick and place machine. :)

tm

...so they can pick up their room and place everything where it belongs.