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Spark won’t climb Jacob’s Ladder I have built a kit for the Jacob’s Ladder de­scribed in the September 1995 issue of SILICON CHIP. I want to know why the spark only travels half the way up the wires? The length of my wires are about 220mm with a gap no bigger than 20mm. How can I make the spark go farther up the wire? (L. C., Albany, WA). • The spark will travel all the way up the wire if the following requirements are met. First, there can be no kinks in the wire as these Mailbag: from page 65 The strong work ethic and individualism brought by the NZ pioneers from the United Kingdom were reinforced in the isolation of NZ hinterland, increasing the concepts of self-worth, egali­tarianism and the importance of the individual to be self-directing. Thus many civil liberties are protected by the “cul­ture”. For these reasons, NZ “pollies” and regulators are reluct­ ant to write and enforce restrictive regulations. Australians have allowed AS/ NZS 3000-2000 Wiring Rules to be interpreted in a legalistic manner. Little imagination is needed with the Australian interpretation to see the work of insurance underwriters in league with powerful legal lobbies and with industry associations and employee unions for the stated purpose of “safety”. But the bottom line is dollars: income from electrical trade employment, consultants’ fees and legal argument and minimising the will cause the spark to stop at this point. Second, the flare or angle at which the wires slope outward towards the top must be very gradual. Also make sure the two wires are exact­ly vertical since the rising spark relies on convection of the heated air (above the spark). Finally the length of spark is ultimately dependent on the coil used. You may be able to obtain slightly more spark if you change the 0.33µF capacitor at pins 2 & 6 of IC1 to a slightly larger value. This will increase the dwell or charge time for the coil. Try a 0.47µF instead. insurance companies’ liabilities and pay­outs for injury and property loss. Quite rightly your “Letter” comments that New Zealanders are not dying like flies from electrocution and I add that if many NZ houses were burnt down due to electrical wiring faults, then restrictive regulations would be enacted. It seems to me that if the governments of Australia were really concerned about stopping “illegal” Notes & Errata Pink Noise Source, January 1997 & Electronics TestBench: the 22kΩ resistor shown connected between pins 1 & 2 of IC1 on the PC board overlay diagram on page 42 (January 1997) should be 220kΩ. The circuit diagram is correct. 2-Channel Guitar Preamplifier November 2000: the circuit diagram incorrectly shows S1 as a 2-pole (DPDT) power switch. It should be a electrical work then every hardware shop in the country would be banned from selling all electrical cable for fixed electrical wiring, and all switch­ es, socket outlets, batten holders and junction boxes. These items are exclusively made for fixed wiring installation. As everyone knows, these are available in “bubble packs” for retail sale to any person regardless of age, gender or qualification. Perhaps supermarkets should be banned from selling replacement light globes. The Australian community would not tolerate such an outra­geous and preposterous erosion of our liberty to “have a go” to make our own repairs. Your “Letter” mentions the need to lobby our politicians to get restrictive electrical worker regulations scrapped but our “pollies” only act on the advice of technical specialists when they see it is to their electoral advantage. I suggest that until we change Australian culture to be more like the New Zealand model, we will keep on the legalistic path (as USA copycats) of more control by bureaucrats who believe more control is good for its own sake. I. Morrison, Marleston, SA. SPDT type and it switches the Active mains lead only. In addition, the parts list for the main PC board contains some errors. First, there should be 6 x 2.2µF NP PC electrolytic capacitors (not five) and a 1 x 1µF NP PC electrolytic capacitor should be added to the list. Second, there should be 15 x 10kΩ resistors and 4 x 150Ω (not 14 & 3). Finally, the 4.7kΩ resistor connecting to pin 3 of IC3 on the overlay (Fig.4) SC should be 27kΩ. WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. January 2001  93