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I just visited the legendary Silicon Valley Electronics Flea Market in Fry’s parking lot in Sunnyvale. Compared to the season’s first MIT flea market, I would have to rate this one much better (although Andrew reported that the second MIT Flea had a much better turnout than the first one that I attended). The lighting here is also much better! I scored a few finds: some miniature connector coax patch cables for $1 each, a bag full of ISO flange claw clamps for $3, one 20K/100W resistor for $1 (after digging through many boxes of high wattage but very low resistance ones), and some small center drills (not in the photo). Not a big haul, but It was great fun rooting through boxes of high tech bric-a-brac. I saw a couple of high vacuum bellows valves, but they had been exposed to some very nasty stuff and were quite corroded inside. There was a fair amount of stainless gas plumbing and components (mostly VCR connectors) likely from the semiconductor industry. If I lived in the Bay Area, I’d definitely attend this one every month.

I was there too! I got an oscilloscope for $20.

Alas, the large Manassas hamfest was a bust. Rained all day here and there, too. We were scheduled to leave at 6AM, but it was pouring and so, we bagged it. Mother nature, she owns it, big time.

Great stuff from the other fests above in this post. We often see a lot of vacuum stuff from scrapped fab lines.

Richard Hull

The electronics flea market in Sunnyvale (formerly Cupertino), CA ended its 2018 season today. Alas, demands of my day job left no time to pack up for selling. Double alas, I went anyway, and fell into binge mode. Brought home many things that are small and inexpensive, or small and free.

Here are a couple of uncommon instruments, seen and left on the table: .
Out of pocket cost was about $25 or $30, in exchange for all the items in this picture: The item to save first, in case of fire, is the DC KOLOVOLTS meter. Not an easy thing to find. Or to want.
The 150 volts AC panel meter is ready to connect -- no external components needed. Most of the other meters were free.

New new lab supplies include large and medium clip leads, a DMM, and a handful of wires with pin receptacles on one end. The bundle of stranded wires with pins on both ends ("for Arduino plugboard") actually came from a garage sale on my way home.

The lamp collection now has a 100-200-300W three-way bulb with mogul base; 175 and 250 W gas discharge lamps with clear globes, and a self-ballasting mercury vapor black light bulb. All in their boxes, altogether $6, from three different vendors. One old rectifier tube that came with a loose cap, an unfamiliar JAN number, and no trace of mercury that I can see. One plain photocathode tube (free).

Then red and a near-infrared optical filters, a pair of 55-volt 315-watt toaster elements (NIB, $1), a needle valve with micrometer screw ($1), and a weird little free tube (spark gap?). The big ticket item, amounting to $3 or $4, is the hand-picked assortment of 2W composition resistors in megohm values and one 100 ohm power resistor (actually sought, and put into service today). Rounding out the bundle is a pair of unused AC capacitors full of Pyranol ($1) and a stepper switch whose relay coils operate an escapement mechanism to turn a toothed wheel ($1).

Here's a closer view of the valve and the funny tube-like thing. The latter has a pin terminal on one end and a pinched-off metal tube on the other. What is it?

Nice valve! I paid more like 30 for mine!

The tiny tube looks like a spark gap tube or a HV gas regulator tube.
The smallest meter looks like a radium laced face and needle job from a WWII comm item used in aircraft. Can't see it all that well.
The large loose capped rectifier could be an 866A but JAN numbered for WWII or Korea.
The nupro valve was the real buy. Looks like swagelok connections.

Richard Hull

Yes yes & yes.
I was picky about the free meters, and at least one looked like it had radium paint.
Haven't tried lighting up the funny little diode.
The valve does have those face-seal connectors, including a metal dent protector under one of the plastic dust caps.

The rectifier says JAN-249? (probable remnant of a fourth digit). Filament seems to heat properly on 2.50 volts AC. I let that run for 15 minutes before applying any plate bias. Then it wouldn't light below 19.7 volts DC (measured from one end of the filament), but finally displayed its mercury content. Here with three different photo exposures; current was about 500 mA for the first two. I have no mogul socket that contacts ring terminal of the three-way bulb. In a regular mogul socket the 200W filament works. The other filament has an appropriate DC resistance.

I foolishly expected the self-ballasting mercury vapor lamp to have a coil or something inside. Nope, just a series incandescent filament. Will be interesting to monitor the current as the Hg capsule warms up. If power is interrupted while hot, it need time to cool down before it can restrike on 120 V. Of course the outer bulb, with black light filter, gets pretty hot for a non-halogen incandescent lamp. Yes, Dennis, I wore good sunglasses during that exercise. Probably should have for the rectifier work, but that device is not an intentional radiator of UV light.

The Internet hasn't satisfied my curiosity about whether some discipline really uses a unit called kolovolt.

The official "arc drop" on Mercury vapor rectifiers is typically 13-20 volts. Officially, in college back in 1964 we had to spit out 13.6 volts when giving Mercury arc drop answers on tests.

Richard Hull