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Author Topic: Carbon Arcs Still Available? Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 07-10-2004 09:04 AM                     The total KVA consumption of a modern solid state rectifier is about the same for single or three phase and with electronic rectifiers the quality of the DC is the same  |  IP: Logged Andrew McCrea Jedi Master Film Handler Posts: 645 From: Winnipeg, Manitoba, Canada Registered: Nov 2000 posted 08-28-2004 12:25 AM                        Ok, it has Super Simplexes as I've recently found out, with a Ballantyne M6 something soundhead. A romour as to how the fire was caused says that the projectionist threw a hot carbon on the floor.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 08-28-2004 08:46 AM                    For Andrew: Ashcraft Super Corelight interior (copper coated negative, rotating bare positive--in this instance they are of the joinable type. Current introduced into the positive via the jaws seen just to the right of the burning tip Box of positives: Box of negatives: The two boxes are not shown to the same scale. The negatives are 7/16" (diameter) x 9". The positives are 13.6mm (diameter). Not sure of the length; maybe 12" or so. But these are the joinables. The regular one piece positives would be 18" or 20".  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-28-2004 10:06 AM                     "Well, such a beast would be an inverter, which certainly exists, but is probably not energy-efficient or cost-effective in the kW range..." Actually an invertor can be made to approach 95% efficiency today. So yes thay can be made more efficient. The cost effectiveness factor would have to be calculated over the life span of use of the invertor. Compare the purchase price to power consumed to length of life span of the unit. The amount of power an invertor generates has no relation to its efficiency either. An invertor that generates 100 watts of power can easily be made to run as efficiently as one that generates 10kw. A really good example are the big motors of 10 hp and up that are now typically invertor driven and are at least 40% to 50% more efficient than the majority of older motors of past years. Over 20 years its possible for these motors to actually pay for them selves in power savings alone! The main advantages are that they(motors, rectifiers, power supplies, etc) are generally pulse width modulated, run at higher and hence more efficient frequencies. The transformers involved are also more efficient because of the high modulating frequencies and are sometimes even the toroid type. There is less chance, sometimes no chance, of extreme core saturation because of the regulation possibilities when pulse width is used to drive an invertor. There is also ALOT less heat loss associated. One point that Gord says above is that the "quality of the DC is the same".... I would have to disagree somewhat with that because any ripple that gets through to the output... and some alsways does... is going to be low frequency in natuire on an iron core rectifer whilst in an inverttor type its going to be high frequency(which is much easier to filter out to begin with). To many circuits the hf ripple doesn't even matter but many circuits are very sensitive to low frequency ripple, Xenon lamps for example. Mark @ CLACO  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 08-28-2004 10:22 AM                    Inverter? For motor drives yes but for lamps? Do you mean a switching supply? Are you calling that an inverter?  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-28-2004 12:14 PM                     Websters....... Main Entry: in·vert·er Pronunciation: in-'v&r-t&r Function: noun 1 : one that inverts 2 : a device for converting direct current into alternating current In reality a switching supply really is an inverter and can be made to work either way. The difference is that you are just rectifing the inverters output to provide DC to something instead of using the amplifiers output directly as in the case of a motor drive inverter. Its also possible to use a feed back loop to control any type of electrical inverting process. Mark  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 08-28-2004 12:33 PM                    I thought the way a switching supply works is to rapidly switch on and off, varying the duty cycle so the voltage across an output cap is maintained to whatever is desired. Where is alternating current being created? Isn't just high frequency pulsating DC?  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-28-2004 01:28 PM                     I can show you the blueprints for some of the Strong Switchers if you happen to find your way to the airport. Remember that I am an industrial spy I actually have a number of them. It is a pulse width(AC) driven amplifier and then the output of the amplifiers is rectified by large stud mounted high speed diodesprobably Shottkys or something similar(this explanation is very simplified of course). If you fed a pulse width modulated aquare wave into a capacitor you are essentially feeding high duty cycle AC into a capacitor which is what a square wave really is. It has to be rectified, converted to DC first. The square wave would eventually cause the capacitor to explode or blow its relief valve because a high level square wave can cause ALOT of current flow through a capacitor which would generate a huge amount of heat really fast. Also I don't know of a switching supply that uses the actual 60 hz incomming for anything. They all have independent waveform generators as the refrence. This refrence is sometime whats actually being modulated and then amplified, others do it differently.I found this on the web. Since sometimes I have a hard time explaining my thoughts.... perhaps it explains it better than I can..... ____________________________________ "They convert the 60-Hertz (Hz, or cycles per second) current to a much higher frequency, meaning more cycles per second. This conversion enables a small, lightweight transformer in the power supply to do the actual voltage step-down from 110 volts (or 220 in certain countries) to the voltage needed by the particular computer component. The higher-frequency AC current provided by a switcher supply is also easier to rectify and filter compared to the original 60-Hz AC line voltage, reducing the variances in voltage for the sensitive electronic components in the computer. A switcher power supply draws only the power it needs from the AC line. The typical voltages and current provided by a power supply are shown on the label on a power supply. Switcher technology is also used to make AC from DC, as found in many of the automobile power inverters used to run AC appliances in an automobile and in uninterruptible power supplies. Switcher technology in automotive power inverters changes the direct current from the auto battery into alternating current. The transformer uses alternating current to make the transformer in the inverter step the voltage up to that of household appliances (120 VAC)." __________________________________________ Mark  |  IP: Logged Howard Johnson Film Handler Posts: 87 From: Felpham , West Sussex, UK Registered: Jun 99 posted 08-29-2004 02:19 PM                     We still have a working Simplex E9 with Peerless Magnarc at the Dome Cinema in Worthing. We use a FP20 with a tower for the usual shows but can run a 2000 foot spool on the Simplex. We have a reel of old adverts we sometimes run. The Simplex is equipped with a Dolby soundhead! We have 2 spare Peerless arcs from the Plaza Oxted when they converted to Xenon which was done to save running costs as discussed earlier. The Plaza Oxted used to have the distinction of running 2 Westars on changeover with 6000 ft spoolboxes carbon arcs and DTS sound!  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 08-29-2004 02:41 PM                    Awesome. Now if only we can find someone providing state-of-the-art picture and sound via something really ancient like a Simplex Standard.  |  IP: Logged

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