On Monday 26 November 2012 20:37:59 kqt4a...@gmail.com did opine: > On Mon, 26 Nov 2012, Jon Elson wrote: > > They are phase angle SCR controllers. You put a variable resistance > > across two of the terminals, and they vary the power to a line-powered > > device. Basically a heavy-duty lamp dimmer. > > can you give me an example of a 21st century equivalent > would this device, a rectifier, and capacitor be adequate for a stepper > power supply > > richard > I can imagine such a circuit, but it has a major downfall unless the output filtering is choke input. This device is NOT suitable for controlling an AC transformers primary circuit due to a likely lack of firing symmetry on the opposite halves of the input voltage waveform. This leads to what is effectively a dc current, or considerable magnitude thru the relatively low resistance primary circuit. It can and has led to some pretty fireworks as the iron core becomes saturated from this current, at which point the irons effect on the inductance becomes a very low value. At that point the circuits current limits are set by the ac source impedance (think Grand Coulee Dam) and the resistance of the primary winding. Conceivably, quite a few kilowatts would be drawn from the power line for those few milliseconds it takes to blow the top off the parts and possibly even starting a fire if the src fuse does not clear within that same half cycle that saturated the iron.
With a fast recovery (think sub-microsecond) bridge at its output, with the bridge feeding a several henry choke between the bridge and _any_ non-stray capacitance, then a regulation circuit could be applied to the 'resistor' input, so the output voltage could be loosely regulated to say 75 volts to feed 80 volt Gecko's with. Used that way, it seem to me the overall efficiency in terms of waste heat generated, should be pretty decent. In some energy conscious locals, that 20 watts a motor saved in PSU heating, would seem to make it pretty appetizing to try. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! Green's Law of Debate: Anything is possible if you don't know what you're talking about. ------------------------------------------------------------------------------ Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
