Magnetic Levitation

Buying the Levitator Parts

How much does it cost? Where do you buy the parts? Is there a printed circuit board?

Total Cost

First the disclaimer: Your mileage will vary! The individual parts aren't very expensive, but if you also have to buy tools (voltmeter, bench power supply, soldering iron, wire stripper, needle-nose pliers, etc) then it quickly adds up to a lot more than I show here. If you have a good parts bin, your price could be a lot less. Substitutions are common (e.g. a different potentiometer, or a fixed resistor instead of a pot), so I encourage you to make your own shopping list starting from this one.

The price is probably under $100, depending on what parts you've got in your scrap box. If you know exactly what you want then buying the few parts you need is as little as $20 total. There are many choices and tradeoffs; it is a little like sewing project where the quality of material and a good-looking visual presentation can run up the prices.

It's a good idea to buy spares. Especially the op-amps, because if they fail then they're certain to die late at night when the stores are closed. :-) It's real hard to get that blue smoke back into the chip; you'll have to buy new parts that contain fresh smoke.

Price List

I don't know if this is a good idea to list prices, but let's see how it works... Although I dislike the prices at Radio Shock, here is the closest part number and price for the parts in my levitator. (Note: This list is current as of December 1999, but will not be kept up to date!) This is merely intended to give you a feeling for the overall cost, and to clearly identify the parts.

Price Part No. Description
US$  Resistors (total = $7.30) 1/4-watt, 5% tolerance carbon-film
0.49 RSU 11344744 300-ohm resistor, pkg of 5
0.49 RSU 11344793 510-ohm resistor, pkg of 5 (need at least 2)
0.49 271-1321 1,000-ohm resistor, pkg of 5
0.49 RSU 11344892 1,500-ohm resistor, pkg of 5
0.49 RSU 11345071 11,000-ohm resistor, pkg of 5
0.49 271-1339 22,000-ohm resistor, pkg of 5
0.49 RSU 11345204 56,000-ohm resistor, pkg of 5
0.49 271-1347 100,000-ohm resistor, pkg of 5
0.49 RSU 11345360 390,000-ohm resistor, pkg of 5
2.89 271-1716 50K ohm potentiometer, linear taper
  Capacitors (total = $2.17)
0.79 272-1053 0.1 uF, 50 volts, mylar film
1.38 272-1027 47 uF, 35 volts, electrolytic, 2@ 0.69
  Semiconductors (total = $11.91)
1.69 276-0143 Infrared LED emitter
1.98 276-0145

Infrared photodetector, 2pkg@ 0.99
(A matched set of emitter/detector is also a good choice as part number 276-142)

2.29 276-1622 Assorted LEDs, pkg of 20
3.16 276-007 LM741 op-amp, 4@ .79
1.99 276-2041 2N3055 NPN power transistor
0.49 276-1101 1N4001 diode, 50v peak inverse voltage, pkg of 2
  Miscellaneous (total = $94.08)
25.98 273-1773 110vac to 12vdc adapter, 500mA, for +/- to control electronics
13.99 273-1770 110vac to 9vdc adapter, 800mA, for coil driver
Note: It is preferred to use a 15v supply, but this is the closest Radio Shark component and will be satisfactory for most people.
21.99 276-169 Solderless breadboard mounted on 4x7" base with non-slip rubber feet. 3 binding posts. 640 plug-in tie-points on 0.1" centers.
9.99 22-402 Dual-scale bench voltmeter, 0-15 or 0-30 vdc
4.49 278-1226 Stranded hook-up wire, 45 feet of 18ga, three spool set in various colors
3.99 278-1215 Solid hook-up wire, 100 feet of 22ga for breadboard jumpers
7.98 278-1345 Magnet wire set, 40' of 22ga, 75' of 26ga, 200' of 30ga (levitator uses about two spools of only 22ga), 2pkg@ 3.99ea
1.49 278-1720 Nylon wire ties, 5-1/4" in various colors, pkg of 20
2.19 278-1638 Spiral wrap, 10 feet, to cover wires to a.c. adapters
1.99 274-659 Barrier strip, 6 terminal, dual row
n/a n/a Wood for base and frame, screws, bolts, washers
  Total $115.46

The parts are non-critical and substitutions can save you money, especially for the power supplies.

Where Did I Buy My Parts?

The cheapest place to shop is a surplus electronics store. I used Radar Electric in Seattle, and Vetco Electronics in Bellevue. Of course, Radio Snack will be the quickest/easiest, but also costs the top $. If it doesn't matter to you if the whole project adds up to $50 vs $100, then you can save a huge amount of time at Radon Shack!

If you know how to build a printed circuit board then skip ahead to PCB plans by Amadeus!

On-line Part Suppliers

There are some large and established parts suppliers on-line:

All these sites are difficult to navigate and hard to find a particular part, but my personal favorite is Digi-Key. Their on-line catalog is in a very nice Acrobat format, and their printed catalog is especially useful with hints and usage notes.

If you have a little experience and know what you want, shopping on-line is excellent. The major drawback of on-line shopping is that the selection is so vast it's hard to decide among all the choices.

Buying a Levitation Kit

Oh yes, you can buy a very nice little kit for $49 US. The kit is from a great article in the February 1996 issue of "Electronics Now". I built their kit and you can read my review. Their contact information is:

   LNS Technologies
   PO Box 501
   Vacaville, CA 95687

They updated the kit in May 2006 and lowered the price, so I know they are still in business and eager to sell you the LEV-KIT.

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