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N_Cook <diverse@tcp.co.uk>: Jul 08 05:15PM +0100 UK, 240V low power practise amp with 2 wire cable and no earth wire. Loud mains hash but finger touch the metal chassis and mains hash noise goes. To a lesser extent of noise reduction , touching guitar body( via guitar lead). 0V of 12-0-12 Tx secondary to chassis ground. 6 100nF, 25V disc ceramics between various points and chassis. Ground lines are all fine, input socket fine. Battery powered source , into aux input, is fine , no hash. Someone has been inside messing about, but nothing obviously missing. As found, the plastic barrel Jalco guitar input socket, does not have a local bond to ground. So i created one and cut the ground line from Prea to PS+PA , as that line is over 1 foot long, no change to mains hash. What is the function of heatsink insulator fibre reinforced matting between Tx and chassis under the 2 mounting flanges, held with 2 steel bolts and washers, damps acoustic resonanace/vibration? Other than replace the 2 core mains cable with 3 core ,any ideas ?

adidevrk511@gmail.com: Jul 07 10:43PM -0700

Pat <pat@nospam.us>: Jul 08 08:01AM -0400 >> When the alarm is activated the 24VDC is removed from the coils and the doors are supposed to be automatically pulled closed by the force of the pneumatic unit. This doesn't always work because in spite of the opposing force applied by the pneumatic unit, in many cases the electromagnets seem to hold enough residual magnetism to keep disks from releasing and the doors from closing. It often becomes necessary to increase the opposing pneumatic force tremendously in order to overcome this.   >> I have discussed this with various manufacturers of these electromagnetic units and in all but one instance have received the same bullshit answer that they've "never heard of this".   >> The one exception was one tech who ventured that perhaps momentarily reversing polarity on alarm before DC drop out might work, however he had never tried it. Does anyone have any ideas about this? Thanks, Lenny   I know this is an old post, but I find it interesting. Would using AC on the electromagnets instead of DC solve the problem?

Rheilly Phoull <rheilly@bigslong.com>: Jul 08 08:16PM +0800 On 8/07/2016 8:01 PM, Pat wrote:   >>> The one exception was one tech who ventured that perhaps momentarily reversing polarity on alarm before DC drop out might work, however he had never tried it. Does anyone have any ideas about this? Thanks, Lenny   > I know this is an old post, but I find it interesting. Would using AC > on the electromagnets instead of DC solve the problem?   Remember the power in these systems comes from a backup battery to make it fail safe. It would involve major rebuild costs to do that.

"pfjw@aol.com" <pfjw@aol.com>: Jul 08 05:46AM -0700 It has been my experience that these beasts fail in three typical ways:   a) they are so seldom checked that dirt accumulates under the leaf and cements the door in place (!!). b) the plate rusts to the magnet. c) see a) above but insert carpet.   All due to systematic and systemic negligence. Under my watch, such devices are tested weekly, typically on Friday at office (or school) closing. I have never seen residual magnetism sufficient to hold the door. Neither plate nor magnet has enough mass for that.   Peter Wieck Melrose Park, PA

Pat <pat@nospam.us>: Jul 08 09:14AM -0400 On Fri, 8 Jul 2016 20:16:52 +0800, Rheilly Phoull >> on the electromagnets instead of DC solve the problem?   >Remember the power in these systems comes from a backup battery to make >it fail safe. It would involve major rebuild costs to do that. Good point! Thank you for the reply.

dansabrservices@yahoo.com: Jul 08 06:25AM -0700 > Remember the power in these systems comes from a backup battery to make > it fail safe. It would involve major rebuild costs to do that.   Not true. Most of the systems that I have seen will automatically release the doors during a power fail. Since these are fire doors, the default is to close them in any "emergency". A power failure is considered an emergency and the doors are released.   As matter of fact, during a fire inspection we will trigger these doors in one of two ways: 1) Fire alarm trip and 2) power failure. In order for the facility to pass the inspection, both methods need to work.   Dan

legg <legg@nospam.magma.ca>: Jul 08 09:38AM -0500 On Fri, 8 Jul 2016 20:16:52 +0800, Rheilly Phoull <rheilly@bigslong.com> wrote:   <snip> >> on the electromagnets instead of DC solve the problem?   >Remember the power in these systems comes from a backup battery to make >it fail safe. It would involve major rebuild costs to do that.   For this service, loss of power would invoke the fail safe condition, without a back-up battery. Fail safe is the de-energized state.   RL

legg <legg@nospam.magma.ca>: Jul 08 10:43AM -0500 >>> The one exception was one tech who ventured that perhaps momentarily reversing polarity on alarm before DC drop out might work, however he had never tried it. Does anyone have any ideas about this? Thanks, Lenny   >I know this is an old post, but I find it interesting. Would using AC >on the electromagnets instead of DC solve the problem?   The OP already had multiple advice that the remanence was highly unlikely to be the issue - so a different coil or drive method would be unlikely to solve it, in an application where the installation has been previously vetted. Fire doors have varying construction, involving metalic or other heat resistant materials, but once adjusted, performance should be repeatable.   It's much harder to get predictable performance from a pneumatic door mechanism and the door it's controlling - without considering any involvement from various external hold/release mechanisms. This is complicated if staff are fiddling with the available adjustments at their extremes, rather than examining other issues such a cleanliness, lubrication or possible obstructions.   I understand his frustration, but safety critical features are best addressed by those responsible for their installation and servicing.   This hardware operates on the principles of an electromagnet, as is more commonly evident in solenoids and relays, so advice on their operation is relevant.   RL

bruce2bowser@gmail.com: Jul 08 07:25AM -0700 John Doe" <always.look@message.header> wrote in message news:nlkrjr$hgn$1@dont-email.me... > "A drone-mounted chainsaw, what could possibly go wrong?"   > http://www.gizmag.com/killerdrone-chainsaw/42605/?li_source=LI&li_medium=default-widget   > Good for another episode of some horror movie.   I you're talking about removing hard-to-get tree branches that you can't reach, then a remote-controlled might be good, but mechanically actuated cutting is still like all of the rest of the cromagnon talk you see about just TOTALLY out-of-date stuff, here.   Instead of using a chain saw, you might be able to use something called a MASER which emits a concentrated beam of microwave energy. So its different from a laser which emits a highly concentrated beam of light that can help with cutting, joining, fashioning, etc...

Micky <NONONObobbyburns1111@gmail.com>: Jul 07 05:02PM -0400 >"Science Unlocks Slimming Effects of Spaghetti" by Premack, Rachel. Washington Post July 7, 2016 p.A3   I use spaghettini. Very slim.

"J.B. Wood" <arl_123234@hotmail.com>: Jul 07 02:45PM -0400 On 07/07/2016 10:36 AM, Pat wrote:   >> There are two wires. One is grounded, the other has -48 volts.   > Not true. POTS lines are balanced twisted pairs. Neither side is > supposed to be grounded (except for old party line ringing schemes).   Hello, and it's the voice frequency (~3 Hz to 3 kHz) part of a 2-wire common battery telephone line that's balanced to (earth) ground to minimize the introduction of common-mode noise. Repeating coils and/or chokes allow the common battery to supply loop current to subscriber sets while not short-circuiting the voice frequencies on the wire pair. Party-line ringing systems aside, it's been common practice in the U.S. to connect the positive terminal of the central office battery to earth (I'm told the reason for this was originally as an anti-corrosion measure). From a DC perspective one of the twisted pairs is earthed (but only at the CO). Measurement with a DC voltmeter at a subscriber set location from the Ring (red) side of the line to ground (something leading back to earth such as a metal water pipe or ground prong input of an AC utility receptacle) will provide confirmation. Just don't leave the meter hooked up this way very long as it will most likely upset the voice-frequency line balance and cause considerable hum to be introduced. Sincerely,   -- J. B. Wood e-mail: arl_123234@hotmail.com

frank <frank@invalid.net>: Jul 07 05:49PM More informations, so I answer to myself just for the record:   > It appear to program most common EPROMs just fine but failed on the > uncommon MCM68764 which I believe is good instead (but I have only one...). > Sure, the MCM is a 1980 vintage, but it was NOS.   I confirmed it is more likely a bug into the programming algorithm for the MCM68764/68766 EPROMs. If I interrupt the programming after the first pass, the EPROM appears to be programmed just fine. Otherwise it makes 20 programming passes from 0 to 1FFF and throws some error. The datasheet for these EPROMs just suggests a simple 1ms write pulse for every address and retry on the same address if not read correctly, so I'm not sure why this programmer should redo all addresses from start for 20 times before giving up. It might be an hardware fault but so far the programmer worked fine on all the 27xxx EPROMs. Also it reads fine the memory and can correctly test for blank of course. I'll try some more exotic models like the 2532 soon.   > Anyone?   I guess it's not so widespread by now.   Thanks Frank IZ8DWF

"Ian Field" <gangprobing.alien@ntlworld.com>: Jul 07 06:33PM +0100 <makolber@yahoo.com> wrote in message news:11b785c0-c1da-402d-9bf7-8d2baa4e28d7@googlegroups.com... >> missing yesterday - but any attempt to save it saves a copy of todays >> picture.   > right click the icon and select refresh (or update) thumbnail   I tried everything I could think of, and still can't figure out the location of the ghost image I thought I'd lost.   Its a fairly old camera that probably didn't anticipate the smallest capacity SD card you can buy nowadays - I'll try it without and see if its still confused.

"Ian Field" <gangprobing.alien@ntlworld.com>: Jul 07 06:46PM +0100 "Ian Field" <gangprobing.alien@ntlworld.com> wrote in message news:bnwfz.20465$RL.9283@fx44.am4...   > Its a fairly old camera that probably didn't anticipate the smallest > capacity SD card you can buy nowadays - I'll try it without and see if its > still confused.   PS: Now its decided to output .AVI files, so I have to download an app to open them.

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