Build your own quartz antenna. These (2) 4-3/8" x 3" x 1-5/16" plastic boxes each have (2) boxes of quartz crystals inside and (2) aluminum U-brackets that are attached to a single screw terminal on one short side of the box. Back in the early 70's, they were originally made to be used in pairs as part of a 300 Ohm antenna. Not sure if they will work with today's TV's but all you need is cabling to connect them and give it a try. Made in Brazil, the antenna capital of South America, probably.

When you could just order this 480-pack of 1/4 watt, 5%-tolerance resistors. You'll get (30) pieces each of 10, 22, 47, 100, 220, 470, 1K, 2.2K, 4.7K, 10K, 22K, 47K, 100K, 220K, 470K, and 1M OHM.

Okay, they’re just strips of metal, but CJ says one of each and a grapefruit will get you at least a “C” at the science fair. The copper electrode is 100mm long x 18mm wide  x .8mm thick (3.94" x .7" x .041”). The zinc electrode is 4” long x 3/4” wide x .027” thick and stamped “ZN”. And both of them are awfully useful for crafters and jewelry makers, too.

Like a third hand in the electronics lab, this circuit-board rack from Elenco® has a pair of stable 6-1/2" legs and 3" tall arms with clips, one spring-loaded, to hold the board. It's a must for any electronics DIY-er. Adjusts from 0 to 9-3/8" apart and lets you rotate the board it holds a full 360 degrees. Both clips and legs lock with thumbscrews.

Attention robotics boffins: Here's a nice, powerful 12-24VDC Mabuchi brush motor with a gearbox and pulley attached. At its nominal 24DC, it spins 45rpm, draws 280mA no load, and stalls a 750mA. 7.5 in-lbs of torque and is rated for continuous duty. Has a 3/4" long x 5/16" flattened shaft with a 4-5/8" dia x 5/16" wide (3/16" ID) single-sheave pulley attached, with a matching O-ring. The gearbox measures 2-3/4" x 3" x 9-1/16". The motor measures 1-1/16"dia x 1-5/8" long and comes with 7" leads and a 2-pin Molex connector.

Great for roboticists, too. It's a mighty-mite, this little 6VDC 45 RPM motor with a right-angle gearbox. Draws 13mA, no load, and stalls at 120mA. Output is through (2) double-flattened 1/4" dia x 3/16" long shafts on opposite sides of the white plastic housing, both with 1/16" dia center holes. Measures 1-7/8" x 7/8" overall. Gear ratio is 228:1.

You get a 10ml syringe of white silicone heat sink compound for use as a thermal coupling for electronics. High conductivity, low bleed and stable at high temperatures. Perfect for you electronic tinkerers out there with a sinking feeling.

In the universe of reed switches, we're assured that this one is quite snazzy. In a 1" x 9/16" x 3/8" housing with a  3/8" mounting wing with (2) 3/32" mounting holes. Trigger distance is approx 1" regardless of magnet strength. Comes with 20" tinned leads. Rated for 400mA at 24VDC. Normally open.

These 36-Ohm ear buds have 15-foot leads, so you could practically leave your pod/pad/phone in another room, with the standard 1/8" plug at the the end that isn't in your ears. We'll send (2) pair because we know you keep losing these things or ripping the wires off (although 15-foot leads may just take care of that little wire problem).

Nice little pulley unit kit includes (1) pulley each at 50, 30, 25 and 20mm and (3) pulleys at 11mm, plus myriad bushings, a 3VDC motor, (2) belts and a belt guide, base, mounts and assorted hardware. Includes graphic assembly instructions, plus a couple of rudimentary drawings with suggested projects. It's a mechanical science project waiting for a home.

This little 1.5-3VDC motor draws just 15mA no load, which means it's just the ticket for solar-cell applications. At 3VDC it spins approx 600 rpm and stalls at 125mA. Measures 1-1/8" long x 15/16" dia with a 5/16" long x 1/16" dia shaft and 3-1/2" leads.

This tiny servo motor can swing approx 90 degrees in either direction via any of the (3) included servo horns with screws on the 3/16" toothed shaft: a 13/16" long single horn, a 1-5/8" long double horn or the 1-5/8" long double horn with (2) smaller cross horns. Draws between 220 and 650mA at 5VDC, and is rated for 25 oz/in of torque. Measures 7/8" x 1/2" x 1-1/16" deep with a pair of mounting wings with 1/16" bores. Wiring is 5V to red, ground to brown and timing pulses to orange. Use any 1-2ms pulses at 50Hz.

If Madame Curie had owned this, she'd be alive today. (She'd be more than 140 years old, of course, but still….) Our Radex RD1503 digital radiation meter evaluates the ambient level of gamma radiation, and can detect objects polluted by beta active radioactive nuclides. It uses a Geiger counter to detect the amount of gamma radiation within 40 seconds. It indicates the ambient dose equivalent in µSv/hr (0.05 to 9.99) and the µRem/hr exposure dose rate on a scale of 0.1 to1.25. The values are displayed on a 1-3/4" x 1-1/8" LCD screen. The presence of each particle is indicated by a clicking sound, for quick identification of affected areas, and it has an audio alarm with 3 adjustable ranges. The unit measures 4" x 2-1/4" x 1" and comes with a detailed manual and technical certificate. Requires (2) "AAA" batteries. Made in Russia. CE.

High tech comes to Am Sci & Surp!! It is here in the form of a Peltier junction, a thermo-electric device that translates electric power into heat, and perversely, into cool. Apply current at 15VDC to the gizmos and they extract thermal energy from one face, thereby cooling it. The heat is dumped onto the other face, thereby heating it. Please note: you must use a heat sink on the hot side or the junction will fry itself, since it can quickly create a 65° C temperature differential in a no load situation. Stack two, or build a cascade to increase the thermal differential created. Or run it backwards. Apply heat or cold to the relevant face and produce a current. Amazing for science projects and experiments. Practical for coffee warmers, beer coolers and mini-refrigerator or warming oven applications. They come with a datasheet. Large is 1-9/16" sq. x 3/16" thick and draws 6A and small is 1-1/4" sq. x 3/16" thick and draws 3A.

Our each is (4) of the blue plastic "D" Cell modular battery holders, approx 3-3/8" x 1-7/16" x 1-1/8" deep without tabs. They slide together either side-to-side or end-to-end or any combination of both, with connecting tabs in both directions. Can be wired parallel or in series. Open tops. Interesting possibilities.

Our little solid-state buzzer is a diminutive 9/16" x 3/32" x 1-1/4" but it buzzes along at 8,000 hertz. Rated for 6VDC 20mA, but works fine with as little as 3V. Mounting brackets with holes on the back of the short sides, 4" wire leads. Lotta buzz for the buck.

These large momentary SPDT push-button switches are rated 10A at 125/250VAC and are mounted to a 2-7/16"dia lens plate with a 1-1/8" long x 15/16 - 2 shaft that comes with a plastic washer and nut. There's also an internal 12V 3W replaceable indicator bulb. Needs 3" of rear clearance. You pick a red, green or yellow lens.

Don't wait or it'll all be gone. You get (4) pieces, 11 feet each, of 18-2 wire, polarized, black with a white stripe and eminently discardable spade-push terminals on both ends. (That's under a nickel a foot, cowboy.) Lamp cord, speaker wire, pretty much anything you run juice to.