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.

This solderable perf board for the electronics hobbyist measure 1-1/2” x 1-3/4” x 1/16” or 3-1/4" x 2-1/2" x 1/16" with 1mm dia copper pads on one side with holes sized for component leads. Has 1/8" dia mounting holes on the corners.

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.

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.

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.

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).

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.

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.

Amps and volts, go together like pretzels and mustard, at least in Philadelphia. Where were we? Yes, you pick from our 0-10VDC in 0.2 volt increments voltmeter or the zero-adjust ammeter (Galvanometer) that reads bipolarity up to 500mA in 20mA increments. Both are in black plastic housings, 4" x 5-1/2" x 3-3/4" with a slanted face and red & black banana jack terminals.

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.

These pillow block bearings have 13-gauge steel mounting straps, 4" long x 1-1/8" with 5/16" x 5/8" mounting slots, and a sintered iron ball unit measuring 1-11/16" dia with either a 5/8” ID or 1” ID brass sleeve. The 5/8” ID one has an oil cup on the top; the 1” dia version has a grease fitting in the same place.

You pick the 500-Ohm 1/2W, 1K-Ohm 1/2W or the 10K-Ohm panel-mount potentiometer, all from Alpha Products® with dust covers over a 17mm base, panel tabs, 6mm dia x 10mm long shafts, and 3mm solder lugs with washers and nuts. Shafts are knurled and slotted, and single-turn. Turn them with press-fit black plastic knobs, 6mm ID x 16mm dia x 18mm tall with pointers in assorted colors of red, orange, yellow, blue, green and white.

This 5-pin socket is already wired with 9" leads in black, red, white, yellow and blue to its quick-disconnect sockets, ready for your 1/4" or 7mm spade terminals. Measures 1-1/4" x 1-1/16" x 1" thick. Matches our 94746 relay.

These panel-mount SPST rocker switches have a switch on one side and a blank face next to it. Rated for up to 10A at 125V and 6A at 250V. Measure 7/8" x 15/16" with snap clips for mounting, a 1-3/16" spacer and quick-disconnect terminals.

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.

If a snow globe and a powered speaker had a baby it would be this tornado light show that whirls to the music, with Bluetooth technology. Makes us proud to know there are electronics engineers out there designing this sort of thing. This 8W unit has a rechargeable battery and USB charge cord, a 1-5/8" dia 70-18KHz speaker and an impeller. Inside the 3-1/2” dia globe is, yes, snow and red, green and blue LEDs that react to sound in a whirlwind effect. Has a micro SD card, a standard 1/8” jack, and 32-foot Bluetooth 2.0 capability. The whole shebang stands 7-1/4" tall on an approx 3-1/2" square base.

By jiminy. A little jumper cord with a modular plug on one end and flat "T" connectors on the other side at the end of dual leads. Wires are insulated, with 3-1/2" of the 7" length covered by a telephone-wire-style gray jacket.

This small 24-tooth pulley is 1-1/16" long with 5/16" of that being a 5/8" dia shaft with a 1/2" x 3/8" flattened bore. The pulley portion is 1" OD x 7/8" ID. In shiny silver aluminum.