CIRCUIT TEXT to go with CIRCUIT.GIF Most people who run coils begin with 120 volts @ 60 cycles. If this is the case with your anticipated power feed, then one of your two feed lines will be a neutral wire (zero voltage), and a slight circuit modification will be required. THIS CIRCUIT SCHEMATIC IMPLIES 240 VOLT OPERATION THROUGHOUT, WHERE BOTH 60 CYCLE FEED LINES ARE HOT, AND, A HIGH VOLTAGE STEP UP TRANSFORMER THAT DOES NOT HAVE A GROUNDED CENTER TAP. Those who start out using 120 volt line feeds usually end up switching over to 240 volt operation in a hurry: the amperage requirements of Tesla Coil power supplies makes 240 volt operation very desirable. However this ZIP package includes the specific instructions required for safe, RF supressed operation when using 120 volt feed lines, and/or, neon sign (grounded center tap) step up transformers. Alternate wiring diagrams for these, and other, modifications are provided in the following suppliments: CHOKE.GIF & CHOKE.TXT, CHOKE1.GIF & CHOKE1.TXT, CHOKE1A.GIF & CHOKE1A.TXT. When and where these alternate wiring diagrams are employed they will be referenced. --------------------------------------------------------------- Starting with the upper left hand corner of CIRCUIT.GIF, the 60 cycle line feed provides power to the circuit. These line feeds are labled 60 Hz in the CIRCUIT.GIF schematic. CP1 refers to Circuit Protection devices. This is a fuse, circuit breaker, or fusable link. The current rating of the Circuit Protection device is dependant upon the current rating of the step up transformer (X1). I allow a 150 - 200% margin over the transformer input current rating when using the plate value of unmodified neon sign transformer(s) {transformer = xfmr or xfrmr}. The text files in this packet contain precise instructions for modifing neon sign xfmrs for high efficiency Tesla power supplies. When using modified neons or other types of step up xfmrs, then I allow a 35 - 50% margin over the plate rated input current of X1. SW1 refers to the power control switch(s). In the old days a knife blade switch was common, but I prefer a remotely operated power relay/contactor. When the sparks are flying I am hesitant to grab hold of live switch: I like a remote operated relay with a step down transformer and a low voltage switch. The choice is yours... Line Filter: These are pretty much self explanatory; except that I run them in reverse. We are trying to prevent the RF generated from the apparatus from entering into the house wiring, not the other way around, which is how these filters are designed. These filters are generally marked on the case, just put the "LINE" side facing towards the coil, the "LOAD" side faces the 60 cycle breaker box. NOTE: alternate filter schematics are given and described/debated in CHOKE.GIF and CHOKE.TXT in this packet. VX1 This is a Variable Xfrmr, Variable Transformer, Powerstat, Variac, Autotransformer, Autoxfrmr, etc.... Some type of variable transformer used to control the input voltage to X1. The current rating on the variable transformer should be matched to the value of the Circuit Protection device. Line Filter: see above. X1 High voltage step up transformer. Typical types include Neon Sign Xfrmrs, Potential Xfrmrs, Plate Xfrmrs, Pole Pigs (pole type power distribution type xfrmrs). This is where circuit modifica- tions may have to be made to the general diagram in CIRCUIT.GIF. If you plan on using a neon sign xfrmr for X1, then plan on modifing BC1 according to the layout given in CHOKE1A.GIF and CHOKE1A.TXT. Precise values and layouts to protect neons and the 60 cycle line supply are given in these documents. Plate type, pole type, or potential type xfmrs are protected according to the layout given in CIRCUIT.GIF and CHOKE1.GIF, CHOKE1.TXT. BC1 is the protective Bypass Capacitor. See the CHOKE documents refered to in the above paragraph depending on transformer type. RFC1, RFC2 are Radio Frequency Chokes: Values and construction details are given in CHOKE.TXT, CHOKE1.TXT and CHOKE1A.TXT. G1 is the main system spark gap. Please refer to AIRBLST.GIF & AIRBLST.TXT or CYLNDR.GIF & CYLNDR.TXT for detailed construction specifications and diagrams of these components. C1 is the High voltage, plastic film, pulse rated, Tesla capacitor. Refer to CAP.TXT for construction details of this component. The general text files from OCT-93.TXT or NOV??-93.TXT contain additional detailed information on these capacitors. See TESLA.TXT for commercial sources of Tesla Capacitance. L1 is the Tesla Tank primary coil. Construction details and theory are extensively covered in the general text files (see the OCT-93.TXT or NOV??-93.TXT) L2 is the Tesla Secondary Coil. Construction details and theory are covered extensively in the general text files. Specific construction details for 200 KHz and 450 KHz coils are given in the general texts included in this packet. T1 is the discharge Terminal. Spheres have been traditonally recommended, but TOROID discharge terminals give the last word in Tesla coil performance. Again... The general text files give complete descriptions and construction guides. It should be noted that the RF GRND (Radio Frequency Ground) is a dedicated Tesla ground: The core of X1 and all grounded compon- ents on the coil side of X1; are grounded to a heavy, dedicated, Rf grounding system. The general text files cover RF grounding extensively. Other coil notes: In the event that X1 is not internally current regulated (neons are internally regulated, the other types are not) then some type of current limiting should be added (in series) to the primary of X1 to prevent "brownouts" and "blackouts" when you throw the switch. Pole types transformers in particular are dangerous without some type of current limiting. Details are given in the general text files included in this packet. Tesla Tank configurations (C1 - L1 - G1) are varied, and need not conform with the layout given in CIRCUIT.GIF; see the layouts in TANK.GIF, TANK1.GIF, & TANK2.GIF for the common variations. There are no related text files for these GIFs, the variations being pretty much self explanatory. The layout given in CIRCUIT.GIF tends to be less brutal on X1 during operation. END CIRCUIT TEXT_ ----------------------------------------------------------------- ----------------------------------------------------------------- CHOKE.TXT TO GO WITH CHOKE.GIF This is a radio frequency (RF) and high voltage spike and kickback protection circuit. It protects your power control cabinet, and the low voltage 60 cycle house wiring. This circuit is recommended for the low voltage side of all types of step up transformers, regardless of taps, grounds, etc. on the windings. X1 is the step up transformer. The center core is grounded to the dedicated RF ground that also grounds the safety gap and the base wire of the Tesla secondary. RFC 1A and RFC 1B are about 5-10 turns of heavy insulated wire (sufficient to carry the current requirments of X1) on a large iron powder or wire ring toroid core. I use 4-6 diameter iron powder toroids and heavy cable to wind these chokes. "Protective Capacitors PC1 and PC2 are not critical and can be rated in the vicinity of .5 to 2 microfarads. Use a voltage rating as high as possible. The usual 400-600 volt capacitors will not withstand kickbacks for very long. 1 KV rating or more should work fine." In place of this circuit, a large heavy duty commercial EMI/RFI line filter may be placed here. These filters offer the convienience of good efficiency in a compact unit. Where current throughputs are high I use several in parallel. Quality commercial line filters employ iron powder chokes, as well as the "PC" capacitors of the circuit at the top of this post. The Line Filters I use also have RF choke coils in the ground path; the ground wire can be run reversed (it is neutral) and can be used to trap stray RF, preventing ground path contamination to the 60 cycle breaker box. I use a minimum of two independent grounds. 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� Date: 08-08-94 15:25 From: Terry Smith To: Richard Quick Subj: Tesla Coils 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� PC1 X1 RFC 1A RFC 2A 컴컴컴컴쩡컴컴커붚컴컴컴程程粘컴쩡컴쿤程程컴�> TO TESLA TANK 컨� )�( � 컫� )�( � � )�( O grn曹컴캑 )�( grnd曹컴컴o SAFETY GAP � )�( O 컨� )�( � 컫� )�( � 컴컴컴컴좔컴컴켸봉컴컴컴UUUUU컴컨컴컴훃UUUU컴�> TO TESLA TANK PC2 RFC 1B RFC 2B RQ> "Protective Capacitors PC1 and PC2 are not critical and can RQ> be rated in the vicinity of .5 to 2 microfarads. One little point of safety, which should be pointed out to the folks with limited electronics safety knowledge, is that PC1 and PC2 would have to be NO HIGHER than 0.1 uFd, in order to meet a 5mA ground current leakage standard. The circuit and values of PC1 & PC2 shown above could be lethal if the building ground connection were marginal or missing. Obviously that would decrease filtering effectiveness. A 120 V isolation xfmr, or additional stages to add both filtering and safety related line isolation, as you later described, would be possible solutions ot that problem. BTW, I have seen foolish and inattentive engineering of power supplies for broadcast equipment from one reputable and fairly quality oriented manufacter, which caused 6 and 12 mA of ground leakage with power on and off, due to similar low cost but irresponsible RF filter cap size choices. RQ> rating as high as possible. The usual 400-600 volt RQ> capacitors will not withstand kickbacks for very long. I RQ> prefer capacitors with ratings of from 2500 to 5000 (or RQ> higher) volts" What are "the usual"? Orange drop or block type small leaded film or mica caps? I would think that current ratings (which would be related to ESR, and filter effectiveness) might be more important than voltage rating, so long as no less than 400-600 volt rated caps were used. At 450 kHz, the Xc of the range of caps we're discussing would be 0.1 to 3 ohms, which makes me wonder if "voltage rating" isn't being substituted for physically larger cap with higher thermal and current limits? Such overall higher rated caps should be more effective as RF filters due to the same lowered ESR which results from other design parameters being increased. Do you know if smaller cap failures are from voltage punch through, or if it's really from cooking due to a 3-5 amp repetitive surge current demand, which small inexpensive caps can't handle? BTW, I'll be Freq'ing your archive tonight. I'm curious about what resonant circuits you might have brewed. Thanks for making it available! Terry (203)732-0575 BBS (1:141/1275) 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� Date: 11 Aug 94 17:01:49 From: Richard Quick To: Terry Smith Subj: Tesla Coils 컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� PC1 X1 RFC 1A RFC 2A 컴컴컴컴쩡컴컴커붚컴컴컴程程粘컴쩡컴쿤程程컴�> TO TESLA TANK 컨� )�( � 컫� )�( � � )�( O grn曹컴캑 )�( grnd曹컴컴o SAFETY GAP � )�( O 컨� )�( � 컫� )�( � 컴컴컴컴좔컴컴켸봉컴컴컴UUUUU컴컨컴컴훃UUUU컴�> TO TESLA TANK PC2 RFC 1B RFC 2B RQ> "Protective Capacitors PC1 and PC2 are not critical and can RQ> be rated in the vicinity of .5 to 2 microfarads." TS> ...PC1 and PC2 would have to be NO HIGHER than 0.1 uFd, in TS> order to meet a 5mA ground current leakage standard. The TS> circuit and values of PC1 & PC2 shown above could be lethal TS> if the building ground connection were marginal or missing. Good point, though yours is a worse case scenario. There were already several reasons why I did not like the circuit above, you just added another reason to the list. TS> Obviously that would decrease filtering effectiveness. A TS> 120 V isolation xfmr, or additional stages to add both TS> filtering and safety related line isolation, as you later TS> described, would be possible solutions ot that problem. My improvements on Harry's circuit above work pretty well, and I have always loved isolation xfrmrs as an additional safety/RF/ spike/surge measure. I am considering the addition of a pair of back to back pole pigs in my low voltage feed lines for just this purpose. RQ> "Use a voltage rating as high as possible. The usual RQ> 400-600 volt capacitors will not withstand kickbacks for RQ> very long. I prefer capacitors with ratings of from 2500 to RQ> 5000 (or higher) volts" TS> What are "the usual"? Orange drop or block type small TS> leaded film or mica caps? Again, I am quoting Harry Goldman above, but generally speaking the "PC" caps used in Harry's circuit are the typical "can" type caps used in capacitive start motors. I have seen a lot of these used (and NO they are not filter caps) simply because they are cheap; surplus caps with a rating of .1 uf @ 400 vac are locally available for around $0.25... TS> I would think that current ratings (which would be related TS> to ESR, and filter effectiveness) might be more important TS> than voltage rating, so long as no less than 400-600 volt TS> rated caps were used. At 450 kHz, the Xc of the range of TS> caps we're discussing would be 0.1 to 3 ohms, which makes me TS> wonder if "voltage rating" isn't being substituted for TS> physically larger cap with higher thermal and current TS> limits? Very possible. TS> Such overall higher rated caps should be more effective as TS> RF filters due to the same lowered ESR which results from TS> other design parameters being increased. Good point. TS> Do you know if smaller cap failures are from voltage punch TS> through, or if it's really from cooking due to a 3-5 amp TS> repetitive surge current demand, which small inexpensive TS> caps can't handle? I don't know. You could ask Harry Goldman (I have posted his SNAIL address should you choose to correspond), as he recommended the above circuit (recently too); I have never used it. But in my experience voltage punch through has only occurred as a result of a typical coiling type "incident" where there was no doubt as to the cause (run away oscillator, direct strike to low voltage feed lines, xfrmr breakdown, etc..). Perhaps this is what he was referring to when he said the lower voltage caps don't last very long. On the other hand a repeated 3-5 amp surge current demand on the filter implies something else is wrong... perhaps he is not properly grounded or choke/filtered at the RF side of the xfmr??? Like I said... I don't know, but I would not recommend the above circuit. END CHOKE TEXT_ ----------------------------------------------------------------- ----------------------------------------------------------------- CHOKE1.TXT TO GO WITH CHOKE1.GIF This is a radio frequency (RF) and high voltage spike and kickback protection circuit. It protects your power supply (high voltage step up xfrmr) and low voltage house wiring. X1 is the step up transformer. The center CORE is grounded to the dedicated RF ground that also grounds SG1 (safety gap) and the base wire of the Tesla secondary. BC1 is a Bypass Capacitor. I use high voltage barium titanate doorknobs, with stacks of four or more in series. A typical rating for a single cap would be .003 microfarad @ 30 KVDC, and using four of these caps in series I get .0007 microfarads at 120 KVDC. Since the AC rating is about half the DC rating on these type capacitors, figure a series stack of four will withstand a kickback of 50-60 KVAC in this use. RFC 1A and RFC 1B are about 15-20 turns (minimum) of insulated wire on a large iron powder core. I use 2" diameter iron powder toroids to wind these chokes. This circuit is not recommened for neon sign transformers unless the value of BC1 is divided in two, and the center of the capacitor stack is grounded with the xfrmr core. (SEE CHOKE1A) �------� | | X1 RFC 1A 컴|컴컴컴|컴컴커붚컴컴컴쩡컴컴컴컫컴컴程程粘컴> TO TESLA TANK | | )�( � � | | )�( � � | | )�( BC1 컨� O | LF1 쳐�. )�( 컫� o컴�. SAFETY GAP | | )�( � O | | )�( � � | | )�( � � 컴|컴컴컴|컴컴켸봉컴컴컴좔컴컴컴컨컴컴훃UUUU컴�> TO TESLA TANK | | � RFC 1B �------� 賈� grnd LF1 is a commercial heavy duty line filter wired in reverse. Where current throughputs are high I use several in parallel. Quality commercial line filters employ iron powder chokes, as well as the "PC" capacitors of the circuit at the top of this post. The Line Filters I use also have RF choke coils in the ground path; the ground wire can be run reversed (it is neutral) and can be used to trap stray RF, preventing ground path contamination to the 60 cycle breaker box. I should note that I use a minimum of two independent grounds. The core of X1, and everything to the right of X1 in this diagram, is grounded separately to a heavy, dedicated, RF ground. This heavy RF ground is also used to ground the base of the Tesla secondary. Note that the core of X1 is grounded. BC1 is a Bypass Capacitor. I use high voltage barium titanate doorknobs, with stacks of four or more in series. A typical rating for a single cap would be .003 microfarad @ 30 KVDC, and using four of these caps in series I get .0007 microfarads at 120 KVDC. Since the AC rating is about half the DC rating on these type capacitors, figure a series stack of four will withstand a kickback of 50-60 KVAC in this use. Where center tap ground type xfrmrs are used for X1 (such as neon sign cores) BC1 must be divided into two units, and the center of the stack must be grounded with the xfrmr core (see the arrange- ment of PC1 and PC2 in the top most diagram). Use no more than .001 or so microfarads per side, as too large a bypass capaci- tance will create an oscillating current in the high voltage windings on your step up xfrmr that will cause the xfrmr to fail. RFC 1A and RFC 1B are about 15-20 turns (minimum) of insulated wire on a large iron powder core. I use 2" diameter iron powder toroids to wind these chokes. END CHOKE1.TXT_ ----------------------------------------------------------------- ----------------------------------------------------------------- CHOKE1A.TXT TO GO WITH CHOKE1A.GIF This is a radio frequency (RF) and high voltage spike and kickback protection circuit. It protects the step up transformer (X1) where the high voltage winding has a grounded center tap (like the typical neon sign transformer). It also protects the low voltage supply side of the circuit (house wiring). X1 is the step up transformer. The core and center tap are both grounded to the dedicated RF ground that also grounds SG1 (safety gap) and the base wire of the Tesla secondary (L2). BC1 and BC2 are Bypass Capacitors. I use high voltage, barium titanate, doorknobs; using typically a stack of three or more in series. A typical rating for a single capacitor of this type would be .003 microfarad @ 30 KVDC; and using three of these caps in series I get .001 microfarads at 90 KVDC. Since the AC rating is about half the DC rating on these type capacitors, figure a series stack of three will withstand a kickback of 45-50 KVAC from the Tesla Tank in this use. Since the centers of these stacks are grounded there is extra (two times) safety margin. Note that the values of BC1 & BC2 must be kept below .001 micro- farads in each stack, and that the center of the stack must be grounded. Failure to observe these specifications will allow parasitic oscillations to set up in the high voltage windings of the step up transformer. These parasitic oscillations are high in current, and will cause the step up transformer to fail. RFC 1A and RFC 1B are about 15-20 turns (minimum) of insulated wire on a large iron powder core. I use heavy 2" diameter iron powder toroids to wind these chokes. This circuit is recommened for neon sign transformers, or any type transformer, where the center taps of the step up windings are grounded to the core. The Bypass Capacitance is divided in two, and the center of the capacitor stack is grounded with the xfrmr core. (SEE: CHOKE1 for other type xfmrs) END CHOKE1A.TXT_ ----------------------------------------------------------------- -----------------------------------------------------------------