TCBA Volume 4 - Issue 1
Page 12 of 18
Twenty plates, a dielectric of 7.8 with each plate having an area of 100 square inches separated by 1/8" glass (.125), one would develop a capacitance of approximately .026 microfarads. If you can get your hands on some Titanium, you can expect a much larger capacity due to the dielectric constant involved.
As you can see from the table, castor oil arid window glass rate very high in availability and usefulness. As previously mentioned in TCBA NEWS, plates separated by glass and immersed in transformer oil, castor oil, or mineral oil are quite effective and have ample breakdown protection. (Caution, transformer oil may be hazardous to your health, a gallon of castor oil may be too!)
Table
| DIELECTRIC CONSTANT | V/0.001" | |
|---|---|---|
| AIR | 1.0 | 20 |
| ALSIMAG 196 | 5.7 | 240 |
| BAKELITE | 5.0 | 300 |
| CASTOR OIL | 4.7 | |
| CELLULOSE ACE | 3.6 | 400 |
| FIBER | 6.0 | 160 |
| FORMICA | 4.8 | 450 |
| GLASS, WINDOW | 7.8 | 225 |
| GLASS, PYREX | 4.8 | 335 |
| MICA | 5.4 | 4000 |
| MYCALEX | 7.4 | 250 |
| PAPER, ROYAL | 3.0 | 200 |
| PLEXIGLAS | 2.8 | 990 |
| POLYETHYLENE | 2.3 | 1200 |
| POLYSTYRENE | 2.6 | 600 |
| PORCELAIN | 5.6 | 70 |
| QUARTZ, FUSED | 3.8 | 1000 |
| STEATITE | 5.8 | 200 |
| TEFLON | 2.1 | 1500 |
| TITANIUM | 140 | |
| TRANSFORMER OIL | 2.2 |
FINDING THE CAPACITANCE OF A SPHERE
C (picofarads) = d (diameter) x 1.4
FINDING THE CAPACITANCE OF A DISK
C (picofarads) = d (diameter) x 0.889
FINDING THE CAPACITANCE OF A CYLINDER
C (picofarads) = d x 2
Capacitor Computer Program
by E. Benson Scott, II, M.D.
LIST
10 HOME
20 PRINT “DETERMINE CAPACITY”
30 PRINT ”@1MHZ V/0.001 INCH”
50 PRINT
55 PRINT “AIR 1.0 20”
56 PRINT “ALSIMAG 196 5.7 240”
57 PRINT “BAKELITE 5.0 300”
58 PRINT “CASTER OIL 4.7”
59 PRINT “CELLULOSE ACE 3.6 400”
60 PRINT “FIBER 6.0 160”
61 PRINT “FORMICA 4.8 450”
62 PRINT “GLASS, WINDOW 7.8 225”
65 PRINT “GLASS, PYREX 4.8 335”
67 PRINT “MICA 5.4 4000”
68 PRINT “MYCALEX 7.4 250”
69 PRINT “PAPER, ROYAL 3.0 200”
70 PRINT “PLEXIGLAS 2.8 990”
71 PRINT “POLYETHYLENE 2.3 1200”
73 PRINT “POLYSTYRENE 2.6 600”
74 PRINT “PORCELAIN 5.6 70”
76 PRINT “QUARTZ, FUSED 3.8 1000”
78 PRINT “STEATITE, 5.8 200”
79 PRINT “TEFLON 2.1 1500”
80 PRINT “TITANIUM 140”
85 PRINT “TRANSFORMER OIL 2.2”
200 PRINT
201 INPUT “DIELECTRTIC CONSTANT ”;K
203 IF K < 0 THEN GOTO 10
204 IF K > 150 THEN GOTO 10
219 PRINT
300 INPUT “AREA OF PLATE IN INCHES (0 IF UNKNOWN) ”;A
305 PRINT
310 IF A = 0 THEN GOSUB 3000
400 INPUT “SEPARATION OF PLATES IN INCHES ”;D
450 PRINT
500 INPUT “NUMBER OF PLATES ”;N
510 IF N < 2 THEN GOSUB 4000
600 PRINT
700 C = .224 *(K * A / D) * (N - 1)
800 PRINT C;” PICAFARADS”
830 C = C / 1000000
850 PRINT C;” MICROFARADS”
900 END
3000 INPUT “LENGTH ”;L
3002 INPUT “WIDTH ”;W
3003 PRINT
3005 A = L * W