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#11
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Aristo cold head
Nicholas O. Lindan wrote:
"john" wrote Aristo also has a device to allow the use of digital timers [with a T-12]. Is it necessary with the F-Stop timer? It shouldn't be. [snip] I don't know the inductive characteristics of the T-12 and don't have any experience with this unit. My guess is it will work, but there is a chance the external 'solid state contactor' may be needed. In any case, plugging the head in and seeing if it works will cause no damage to the timer. I do not know the inductive characteristics of cold light heads either. If the load on the step up transformer were resistive, the load would be reflected back through the transformer and place a resistive load on the timer and the power company. Now a gas discharge tube is not resistive, but it probably has a resistor in series with it to reduce the peak current through the tube, so it may be more resistive than the tube itself. -- .~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 20:50:01 up 10 days, 13:22, 3 users, load average: 4.61, 4.50, 4.33 |
#12
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Aristo cold head
"john" wrote in message m... "Richard Knoppow" wrote in message m... ( saltsman enlarger, Aristo T12 cold head) If you have the original shutter it will work well with the cold light head, they want to run continuously. [... snip excellent information] No shutter came with it, but I have a 110V shutter from old long-roll school camera that will fit in front of either lens. Does your Saltzman have one or two support rods for the bellows? It has two, Richard, with the worm-drive rod between them, driven by a sintered bronze gear. I can make pictures to put online if you wish. John You have the more elabrorate version of the enlarger. The cheaper (but not cheap) one had the single support rod. This type was also used for aerial mapping and similar applicatons. It should have a focusing wheel to drive the bellows. Some of the larger models also had a small handwheel to operate the stop ring on the lens. Photographs would be interesting, I suspect many have never seen a Saltzman. I have an ancient Saltzman catalogue somewhere. I really must search it out. -- --- Richard Knoppow Los Angeles, CA, USA |
#13
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Aristo cold head
"Richard Knoppow" wrote in message m... "john" wrote in message Does your Saltzman have one or two support rods for the bellows? It has two, Richard, with the worm-drive rod between them, driven by a sintered bronze gear. I can make pictures to put online if you wish. John You have the more elabrorate version of the enlarger. The cheaper (but not cheap) one had the single support rod. This type was also used for aerial mapping and similar applicatons. It should have a focusing wheel to drive the bellows. Some of the larger models also had a small handwheel to operate the stop ring on the lens. This one has two hand-wheels below the baseboard. One raises and lowers the head assembly using two chains that run up and down the inside of the main column, and the other wheel moves the bellows (focus). It has another pair of smaller hand-wheels on the horizontal supports (of the triangulated head support) to move the head to and fro. Today I am measuring those parts to see if I can add a belt or lightweight chain drive from one of the smaller wheels to drive the other: this would allow the operator to move to-fro using one wheel and obviate having the enlarger sit 30 inches from the wall. (Or a person could just disengage the worm-screw and push/pull by hand.) I would very much like to work out a remove F-stop control. Will think about it. There are mounts for other things such as the red filter rod which are empty right now. And an odd part that I cannot figure out. If I can get a digital snapshooter I will make some pictures and post the address. |
#14
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Aristo cold head
"Jean-David Beyer" wrote
Now a gas discharge tube is not resistive A gas discharge tube has a negative resistance: If you increase the current it will lower the tube voltage. Modeling the lamp as a constant voltage, though, is good enough for most circuit analysis - the result is like driving current backwards through a battery, the voltage on the 'battery' is the arc voltage. In this model the lamp has zero resistance. Since the lamp is pretty much a short circuit - zero resistance - there needs to be a 'ballast' in series with the lamp. The ballast can be a resistor, capacitor or inductor. The ballast impedance (the general term for something that opposes current) controls the lamp current. In almost all equipment the ballast is either inductive or capacitive - called a reactive ballast. Resistor ballasts are sometimes found in very old equipment. A reactive ballast will draw current 90 degrees out of phase with the power line. The power that it blocks is stored in either a magnetic field (inductor) or an electric field (capacitor) and given back to the power line in the next half cycle (a sloppy explanation, but probably good enough). A resistive ballast dissipates the power as heat and the power is gone forever. The reactive ballast causes the system to draw extra current, though not power. This upsets the power company, means larger wiring and transformers are needed and raises the electric bill if your meter charges you for VARs. Large lamp power supplies include power-factor correction by adding compensating inductance to a capacitive ballast power supply or compensating capacitance to an inductive ballast power supply. This makes the lamp system draw the least amount of current and look like a resistor to the power line. http://en.wikipedia.org/wiki/Power_factor Putting a capacitor of the right value at the input to an Aristo lamp will make the system look like a regular old light bulb and there will be no inductive kick when it is turned off. However, because of the capacitor there will now be a current surge when the lamp is turned on. "Pay now or pay later." These problems can be eliminated by connecting the power when the AC voltage is zero and disconnecting the power when the AC current is zero. This is what Aristo's 'solid state contactor' achieves. -- Nicholas O. Lindan, Cleveland, Ohio Darkroom Automation: F-Stop Timers, Enlarging Meters http://www.darkroomautomation.com/index2.htm n o lindan at ix dot netcom dot com |
#15
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Aristo cold head
"john" wrote in message m... "Richard Knoppow" wrote in message m... "john" wrote in message Does your Saltzman have one or two support rods for the bellows? It has two, Richard, with the worm-drive rod between them, driven by a sintered bronze gear. I can make pictures to put online if you wish. John You have the more elabrorate version of the enlarger. The cheaper (but not cheap) one had the single support rod. This type was also used for aerial mapping and similar applicatons. It should have a focusing wheel to drive the bellows. Some of the larger models also had a small handwheel to operate the stop ring on the lens. This one has two hand-wheels below the baseboard. One raises and lowers the head assembly using two chains that run up and down the inside of the main column, and the other wheel moves the bellows (focus). It has another pair of smaller hand-wheels on the horizontal supports (of the triangulated head support) to move the head to and fro. Today I am measuring those parts to see if I can add a belt or lightweight chain drive from one of the smaller wheels to drive the other: this would allow the operator to move to-fro using one wheel and obviate having the enlarger sit 30 inches from the wall. (Or a person could just disengage the worm-screw and push/pull by hand.) I would very much like to work out a remove F-stop control. Will think about it. There are mounts for other things such as the red filter rod which are empty right now. And an odd part that I cannot figure out. If I can get a digital snapshooter I will make some pictures and post the address. The filter rod was also used to hold the shutter. The original was a two blade arrangement similar to a Packard shutter worked by a foot pedal. Not all had the iris control and I don't know the details of how it was coupled. One option was a condenser lamphouse with about 14" condensers and a mirror arrangment for the lamp. These had a focusing control for the lamp on the housing and its possible some had a remote handwheel for this also. I wish I could find my catalogue but it got boxed up. Time for some garage cleaning I'm afraid. You probably need a five foot ladder to go along with the enlarger. Saltzman also made a very heavy, geared, tilting baseboard for perspective correction. I've only seen pictures of these. -- --- Richard Knoppow Los Angeles, CA, USA |
#16
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Aristo cold head
"Richard Knoppow" wrote in message
m... The filter rod was also used to hold the shutter. This one has provisions for two rods, each about 1" from the edge of the lens, extending down as far as one wants to make a rod. I'm a little concerned that shutter movement will cause vibration shake, however subtle, so I might mount the shutter from a sliding arrangement on the mail column, which just cannot possibly move. (750 pounds of it). Two more rods can be added with simple drilling and tapping. So much real-estate on this thing! You probably need a five foot ladder to go along with the enlarger. Heh! I have a vision of Watson on the ladder, "Mr. Holmes, is it correct now, Sir?" Saltzman also made a very heavy, geared, tilting baseboard for perspective correction. I've only seen pictures of these. Over the years of building things like Harleys http://www.digoliardi.net/butcher.jpg , working on tractors, building cars and rebuilding VWs http://www.digoliardi.net/58.jpg , http://www.digoliardi.net/bug_n_brad.jpg has made me comfortable with making large things. A geared baseboard would be simple. But the demand for such a thing is a market of One! |
#17
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Aristo cold head (Richard K.)
Richard, here a just a couple snapshots of two parts of the Saltzman. The
upper section of the snapshot shows the front lower with the large two hand-wheels. Left is focus and right raises and lowers the whole head. The close-up is the rear of one horizontal bar of the head section. Turning the wheel moves the head forward and back. The other is exactly the same. They were missing the gears, retainers, and spacers - everything but the wheels. I haven't got the connecting chain yet (#40 chain, I think ten-pitch). Got the hubs, spacers and gears at the tractor parts shop today. It's hard to shoot snapshots in the shed. This was done with the doors open to the 6pm MinneSnowta May sun. |
#18
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Aristo cold head (Richard K.)
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#19
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Aristo cold head (Richard K.)
On 5/18/2008 5:58 PM john spake thus:
Duh! I forgot the link: http://www.digoliardi.net/salt1.jpg OMG, I'm drooling; a real piece of Industrial Equipment. Should be a centerfold in some magazine. Great stuff! Good luck, and please keep us informed of future developments. -- The best argument against democracy is a five-minute conversation with the average voter. - Attributed to Winston Churchill |
#20
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Aristo cold head (Richard K.)
"David Nebenzahl" wrote in message
s.com... On 5/18/2008 5:58 PM john spake thus: Duh! I forgot the link: http://www.digoliardi.net/salt1.jpg OMG, I'm drooling; a real piece of Industrial Equipment. Should be a centerfold in some magazine. Great stuff! One of my brothers, an expert in ancient warfare, alikened it to a seige machine. So if it doesn't work out... |
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