tag:blogger.com,1999:blog-1592992209402300549.post5348593100181375005..comments2024-03-28T08:06:43.198-04:00Comments on The Silicon Graybeard: Happy New Year 2018SiGraybeardhttp://www.blogger.com/profile/00280583031339062059noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-1592992209402300549.post-10967691194211324712018-01-05T11:08:08.376-05:002018-01-05T11:08:08.376-05:00You probably have a 5 amp model. I checked a loos...You probably have a 5 amp model. I checked a loose Variac sitting in my shop. It is rated for 120V 10A at 50/60Hz. The model number is W10 and the core is close to 6" in diameter.<br /><br />I've probably beaten the subject about to death by now so I'll sign off by wishing you the best of luck with your project. As you have already noted, Variac's are great tools for troubleshooting stuff with power supply problems or for gently powered up equipment that's been sitting for a while, tube stuff particularly. Can't prove it, but I believe I've re-formed more than a few sketchy electrolytic caps by taking a half hour or so to gradually bring up long idle gear.<br /><br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-34014727690024115292018-01-04T21:47:28.311-05:002018-01-04T21:47:28.311-05:00It's close to a 4" core - around 4.15 - b...It's close to a 4" core - around 4.15 - but I recall the opening in the sheet metal had to be 4.72". There's a lip that's about 1/16" bigger diameter than that and I don't really have calipers with jaws long enough to directly measure it, so I was sweating it. The variac sits on the lid on that lip but clears the inner rim I needed to clear. <br /><br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-73722717443323396522018-01-04T21:38:08.386-05:002018-01-04T21:38:08.386-05:00I should have added that a model number, if you ca...I should have added that a model number, if you can find one, may give you a clue as to ratings. Been a while, but a number at the end usually gives the maximum rated current, input and output. If you have nothing, a core roughly 4" in diameter typically was 5 ampere capable. A core closer to 6-7" in diameter typically was good for 10 amps. 400Hz models were smaller, but yours looks like a 60Hz model. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-51396544434506053812018-01-04T18:32:25.775-05:002018-01-04T18:32:25.775-05:00You are very welcome! Definitely fuse the output....You are very welcome! Definitely fuse the output. All of GerRad's packaged Variacs are done that way given that Io x Vo roughly equals Ii x Vi due to transformer action. You can find schematics at eDebris if you're interested. A Kill-A-Watt is a good solution when you need to know real power. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-81160679448962553822018-01-04T16:45:29.856-05:002018-01-04T16:45:29.856-05:00Thanks for that input. I was going to put a fuse ...Thanks for that input. I was going to put a fuse on the line input side, but not both sides. I'll take a good look at that. It should be relatively easy to add. <br /><br />The variac I have is an eBay special and it has no markings for current or power ratings. I just think of it as 0 to 130 on the output - my main use will be to bring up some old gear with a lower line voltage. I have a Kill-A-Watt meter that can tell me the power draw in watts but without ratings, it's hard to know when to turn it off. <br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-78059766347016512272018-01-04T12:57:31.703-05:002018-01-04T12:57:31.703-05:00Couple of suggestions for what they are worth:
1....Couple of suggestions for what they are worth:<br /><br />1. Fuse both the input and the output. If only one fuse make sure it's on the output. I learned the hard way many years ago that a short on the output with a low setting for output voltage will burn up part of the winding without taking out a fuse on the input. GenRad versions use fast blow fuses.<br /><br />2. Consider installing a meter for volts/amps/watts rather than just volts/amps. Often nice to have real power and small digital meters that give all three measurements are readily available at low cost on eBay.<br /><br /><br />Happy New Year!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-41783860729439056202018-01-01T17:01:19.986-05:002018-01-01T17:01:19.986-05:00Happy New Year, Graybeard.Happy New Year, Graybeard.Borepatchhttps://www.blogger.com/profile/05029434172945099693noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-21905242137914898042018-01-01T16:45:00.492-05:002018-01-01T16:45:00.492-05:00You could put a stepper motor drive on the variac,...You could put a stepper motor drive on the variac, reduction gearing with a toothed rubber timing belt. No, I don't know what you would use that for. Maybe CNC electroplating or etching with a probe, something where the current has to vary with the area or separation distance, which changes by CNC. CNC EDM.<br /><br />I think "retirement" means you have ascended into a post-scarcity society and you no longer have to work for a living. However, it doesn't mean you no longer have to work, as meaningful work is necessary for human happiness. Here are suggestions for projects which I would love for you to work on:<br /><br />Voice encryption for cell phones and half duplex radios. A little box to process audio. Does crypto against a one-time pad on a thumb drive, so a half duplex radio doesn't have to do a key-exchanging handshake or have fancy synchronized clocks, and it can broadcast many to one. Offered as a kit with cell phone headset connectors.<br /><br />Portable software defined radios with crypto built in. Lots of extra CPU cycles for tinkering. SDR to take advantage of newer modems which don't fit through existing FM. Two radios, VHF to similar VHF with no repeater, and HF for NVIS. Offered as a kit, to transfer regulatory liability to builder and meet whatever the equivalent of the 80% receiver rule is for the FCC.Anonymousnoreply@blogger.com