I wanted to test the bulb before I installed it.  No point in fitting it to the 'scope if the AA batteries won't power it.  I don't have a power-source.  So I scrounged some speaker-wire, taped the AA's together, and taped the speaker-wire onto the ends of the "battery pack."  The voltmeter confirmed I had 3V power at the end of my test leads.  Just for giggles, I applied the leads to the old blue bulb.  As I very much expected, the old bulb didn't light.  (Which is good -- now Nicole won't kill me for purchasing an unnecessary replacement LED.)

When I touched the leads to the LED, it lit.  Huzzah!  I have a working bulb, that can be powered by the 2 AA batteries that fit into the microscope's base.

So why light?!?  That's the LED, installed in the microscope.  The batteries are in place.  I confirmed I have power at the bulb contacts, and at the bulb.  It's the same batteries, the same LED -- the only difference is the wires.  Instead of the test leads, power's through the wires in the microscope.  And those are working, because I have power at the contacts.

I just don't understand it.

While visiting Nicole, we went to the Goodwill Store (great place to get a printer, if you need one).  This was in the locked "really cool stuff" display, along with a bunch of games, a couple of RockBand/Guitar Hero controllers, a Wii Fit balance board, and a load of jewelry.  The mirror worked, I could see through it, the knobs turned easily, and it was $15.  How could I go wrong?  So Nicole indulged me.





As you can see (click), this is a JASON Model No. 712 Deluxe 900x Zoom.  Monocular (single eyepiece) with a 3-objective turret and both a reflector & bulb illuminator.  i.e., a basic student microscope from the 60s.  It's made of non-ferrous metal, not plastic, and chrome where anti-corrosion plating makes sense.

The kit is leather-over-wood, with flocking on the inside.  Some of the tools are missing.  The spatula, tweezers, scalpel, and some metal pipe-thingy are present.  There are no slides, prepared or otherwise.

The electrical socket (first picture, on the base, near the connector) appears to be in good working condition.  I was able to measure 3V AC at interior points.  I was disappointed to discover the transformer (the gray brick in the first picture) is only a step-down.  It drops the wall-current from 110V to 3V, but it doesn't convert it from AC to DC.

The illuminator is, in my ignorant opinion, pretty neat.  One surface is a mirror.  The other holds a blue-coated "classic" flashlight bulb.  The metal ball-bearing-looking thing on the side of the illuminator is a contact-switch.  When the bulb-side is uppermost, the ball's held against a small plate built into the base.  That completes the circuit and energizes the lamp.





This is meant to be a portable device.  In addition to wall-current, the lamp will run off of 2 AA batteries.  Space for the batteries is in the base.  I checked these, and the electrical connections appear to be functional here, as well.  Which is good, because here's where the complications begin . . .

First, some previous owner (or maybe high school students, who knows) didn't understand how to tighten the screw holding the eyepiece to the barrel.  It's been over-tightened so many times, there are holes gouged into the fitting.  But, the holes are all in 1 quadrant.  So I just rotated it and gently tightened the screw.







The bulb is burned-out.  Not surprising, given its probable age.  But I can't find an exact replacement.  Apparently, the bulb uses a tungsten filament.  These are no longer used because they consume a lot of energy, get very hot, and produce yellowish light (thus, the blue corrective film).  No one uses these anymore.  Student-grade microscopes use LEDs.  (Low-end pro-models use flourescent, and better models use remote halogen light sources with positionable fiber-optic tubes.)  I was hoping the transformer was also a rectifier.  Unlike bulbs, LEDs aren't able to run on either AC or DC.  Not a big deal, I just have to find a cheap LED that'll fit into the bulb socket, and then run it only on batteries.  (In fact, I found and ordered such a bulb.  It cost a few cents less than the microscope.)  Now I just need some slides.

Maybe Aidan & I can look at whatever's living in goopy pond water in a few weeks . . .