Yes, and it isn't nice to fool with Mother Nature. I got nailed between finger and elbow at 25KV from a huge capacitor bank supplying a hydrogen thyratron switch tube - OWWWW. I was reaching into the wire cage and shame on me, I didn't have the ground strap on the bus. I knew better .001 second later. Oh, and having a screwdriver in your hand in the vicinity of the neck of a CRT is another no-no. The anode and the glass envelope is quite a nice Leyden jar! Those CRTs stay charged up a long time, esp. the big old metal jacketed color tubes. My hand was numb for quite a while on that one. ICs are for wimps! Bob ----- Original Message ----- From: Scott Decker <[log in to unmask]> To: <[log in to unmask]> Sent: December 15, 1999 12:03 PM Subject: Re: [DC] PWB High Voltage Material Choices? : Why Bob, : It sounds like you have had the unfortunate discomfort of that nasty HV : stuff too... Ah yes, the old one hand in the pocket thing. I do remember it : well. Your words are well taken about the High Altitude part also. I worked : with a customer that needed a light fixture in a large cable drum, (cable : was a mile long LF antenna) and as it turned out they almost didn't need to : power the light. The corona around the fixture was so bad AND bright, the : comment was, "we don't need no ..... power to the light". Anyway, I just : wanted to make these comments that as most of you may have guessed, don't : have a lot to do with the subject, I just had to type something on the : keyboard. :-) <G> : Have a good holiday everyone... : : Regards, : Scott Decker : : AKA: PadMasterson : Mentor Design Supervisor, Portland : 7245 NW Evergreen Pkwy., Suite 100, Hillsboro OR 97124 : (503)531-2050 ext. 1820 FAX: (503)531-2051 : [log in to unmask] <mailto:[log in to unmask]> : <mailto:[log in to unmask] <mailto:[log in to unmask]> > : Tyco Design : Formerly Praegitzer Design, The Fine Line in Printed Circuits : : : : -----Original Message----- : From: Bob Landman [SMTP:[log in to unmask]] : Sent: Wednesday, December 15, 1999 8:28 AM : To: [log in to unmask] : Subject: Re: [DC] PWB High Voltage Material Choices? : : Greg, : : One item you need to know is the maximum working altitude. At low : air : pressure, arcing and corona are a serious problem. 30KV is certainly : going to produce corona if there are any sharp points. Conformal : coatings help - make sure the material can withstand the HV and : ozone : production without degrading significantly. : : You have to assume that dirt is attracted to the board due to static : field effects. The conformal coating makes sure that the dirt can't : short out the board. Look inside any TV monitor and you will see : that : they are filthy after a few months of operation but they keep on : working. That's good design. Also, assume that this dirt reduces : heat being shed by the parts (forced or natural convection effects : are : reduced as dirt is not a good heat conductor. : : Just be as conservative in your design as $$$ will allow. (and keep : your fingers away and my favorite rule around HV is that I always : keep : one hand in my pocket at all times [across the chest HV is deadly : stuff!) : : Bob : : ----- Original Message ----- : From: Greg Kaskey <[log in to unmask]> : To: <[log in to unmask]> : Sent: December 15, 1999 10:07 AM : Subject: [DC] PWB High Voltage Material Choices? : : : All, : : I hope you are doing well. : : What PWB Material do I call out for one that is 0.074 inch thick and : it does : High Voltage Multiplying with 30K Volt Output? : : The board has no solder mask and is encapsulated in a "Black, Rubber : Like : Material". Also, the Board looks like it has some kind of clear : coating that : does not remind me of a "normal" protective coating which is applied : to the : entire finished assembly; it is soft vs. hard and can be easily : scraped off. : : What questions would I need to ask to determine some of the material : choices? : : Thanks for Helping, : : Greg Kaskey : Sector Electronics, Inc. : V: 770-955-8044 : E: [log in to unmask] : : ____________________________________________________________________ : Get free email and a permanent address at : http://www.netaddress.com/?N=1 :