| BIG TESLA COIL PAGE |
| The big sparks were always one of my dreams. |
| Fres = 200-300 kHz |
| PSU potential transformer, 600 VA, Np / Ns = 1 / 60, 220 vac @ 50 Hz from the mains. BALLASTS two ballast coils used for high pressure Hg lamps (250 VA, cos f = 0,56 each), connected in parallel. So, I suppose that I am using under 500 VA because the ballasts and the transformer run cool. SPARK GAP Vacuum static spark gap (sucker gap); the distance between the electrodes can be modifyed in real time with a long PVC pipe. PRIMARY CAPACITOR EMMC array: 2 strings, each string with 10 minicaps (100 nF @ 1600 V polipropilene, each), connected in serie, with bleeders on every cap (10 Mohms @ 1 watt ); the two strings are connected in parallel for a Ctotal = 20 nF @ 16,000 volts. I can add another string for a total of 30 nF @ 16,000 volts, when I use the toroid number 3. PRIMARY COIL archymedic spiral type, made with 1 cm diameter soft copper tubbing, mounted on PVC pipe supports, with plastic spacers and strike ring at 3 cm from the coil surface. N = 12 turns, average radius = 8.85 inches, inductance (L) = 63.0776 microH, taped at turn 5. SECONDARY COIL GREY PVC pipe (it works!!) covered with one layer of black varnish (used for LV transformers), with end caps; wound lenght = 21.06 inches, total lenght = 22.63 inches, diameter = 4.33 inches. I used 0.7 mm diameter magnet wire harvested from old transformers. N = 749 turns. Inductance (Ls) = 11378.04 microH, Cself = 8.335 pF. The finished secondary was not varnished. The secondary is connected with the toroid through a metalic ring bell. TOROIDS They are made with flexible dryer duct centered with inox plates (toroid 3) or plastic plates covered with aluminium foil (toroid 2) Toroid 1: outer diameter = 10.80 inches, cross diameter = 3.34 inches, C = 11.77 pF Toroid 2: outer diameter = 14.96 inches, cross diameter = 3.34 inches, C = 16.30 pF Toroid 3: outer diameter = 21.65 inches, cross diameter = 4.33 inches, C = 23.15 pF GROUND I used an artificial ground SAFETY GAPS No safety gaps. The spark gap was connected in parallel with the output from the potential transformer. |
| RESULTS: Cp = 30 nF, using toroid 3 . SPARKS = 70 CM (27 INCHES) |
| Cp = 20 nF, using toroids 1 and 2. SPARKS = 90 CM (34-36 INCHES) |
| Next steps: one more ballast, bigger tank cap, maibe a dual MOT PSU. |
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| PICTURES |