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Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Jun 11 11:31AM -0400 On 6/9/19 5:31 PM, David B. wrote:   > Interesting. Do you know a lot about the subject?   >> Cheers   > Thanks for responding, Phil. :-)   I'm by no means an expert on it, but some IBM colleagues of mine did some interesting work on that back about 2000-ish, so I took an interest.   Cheers   Phil Hobbs   -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510   http://electrooptical.net http://hobbs-eo.com

three_jeeps <jjhudak@gmail.com>: Jun 11 07:56AM -0700 A colleague drops by my office toating a Tek R293 Programmable pulse generator and power supply and asks "Can I use a power supply?" followed by, I haven't turned it on in 35 years.... Having never seen one of these before (its circa 1966) and thought it might be an interesting thing to restore, even though I have never and probably will never have use for such a thing.   Looking through the manual scanning for the semiconductor parts list (and looking for the 'special' Tek parts, I see designations on a number of diodes: Snap Diode, Check. No number of any sort.   I never heard of one of these so google is my friend....(aka snap off diode or charge-storage diode or memory varactor) studied the schematics of the pulse generator a bit and realized what a neat device and interesting circuit design.   It probably has a lot of bad parts, given the age, and while repair would be quite a learning experience, my basis questions are: 1) how to determine the snap diode characteristics for this unique tek part? 2) and what are the chances of finding a reasonable substitute?   Assuming one of the snap diodes in the unit still functions, I could use a curve tracer and get some general parameters: Breakover voltage, approximate current range, reverse blocking voltage, leakage, etc. But determining the switch time would be critical in this application as that dictates the pulse characteristics.   Another thing that is of interest is this statement from Wikipedia: "The main phenomenon used in SRDs is the storage of electric charge during forward conduction, which is present in all semiconductor junction diodes and is due to finite lifetime of minority carriers in semiconductors." Finite lifetime of minority carriers....I assume when switching from forward conduction to reverse the minority carriers are quickly reversed in their flow given the abrupt change of voltage polarity? J

John Robertson <spam@flippers.com>: Jun 11 08:15AM -0700 On 2019/06/11 7:56 a.m., three_jeeps wrote: > "The main phenomenon used in SRDs is the storage of electric charge during forward conduction, which is present in all semiconductor junction diodes and is due to finite lifetime of minority carriers in semiconductors." > Finite lifetime of minority carriers....I assume when switching from forward conduction to reverse the minority carriers are quickly reversed in their flow given the abrupt change of voltage polarity? > J   Not sure about the Snap Diodes - you might want to check archive.org or bitsaver.org for the Master Electronics Catalogs from that time for specs. Sound like fast recovery diodes to me...   However in most cases running an ESR meter (Like Bob Parker's Blue ESR meter kit) over the various capacitors will find a few bad ones at which point the power supply may well work. Caps and electrical connections are the weak link in electronics...   Just was playing with one of Bob's latest prototype ESR meter designs yesterday which is a talking ESR meter and working on a sound board with low volume. Having the meter talk to me (Bob's voice) was handy in that I didn't have to take my eyes off the job and things went very quickly. The meter going down to 0.001 ohms is handy too...   Nag Bob if you want to see these in production, he isn't sure there is a market for a talking ESR meter...   He is currently working on this version of a simple ESR meter kit:   https://www.youtube.com/watch?v=o25gLeakcbM     John :-#)#   -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out."

Cursitor Doom <curd@notformail.com>: Jun 10 06:33PM On Mon, 10 Jun 2019 03:15:20 -0500, Fox's Mercantile wrote:   > Good Lord, what are you installing Linux on, eMachines? > I've been doing Linux installs for the past 25 years, I've NEVER had a > failure.   Same here. Never even heard of one!         -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

Roger Blake <rogblake@iname.invalid>: Jun 11 12:26AM > Same here. Never even heard of one!   I think early on there may have been some laptops where fans were not handled properly, causing things to run too hot. Don't know if it rose to the level of hardware failure though.   -- ----------------------------------------------------------------------------- Roger Blake (Posts from Google Groups killfiled due to excess spam.)   NSA sedition and treason -- http://www.DeathToNSAthugs.com Don't talk to cops! -- http://www.DontTalkToCops.com Badges don't grant extra rights -- http://www.CopBlock.org -----------------------------------------------------------------------------

~misfit~ <shaun.at.pukekohe@gmail.com>: Jun 11 10:12PM +1200 On 10/06/2019 4:31 PM, bitrex wrote:   >> Jon   > The last Dell laptop I had used a three-wire PSU that locked you in to buying only Dell-branded > power bricks..... <snipped> I've never seen that on Dell's corporate range of laptops, only on the low-end retail things. The corporate ones usually are capable of docking or using different size PSUs depending on needs so are left 'flexible'. Also they've been using the same 19V rating and connector now for quite a while so that customers can use their old PSUs and docking stations. (That said the latest Dell 'docking stations' are in fact wireless so not really docking stations at all.) -- Shaun.   "Humans will have advanced a long, long way when religious belief has a cozy little classification in the DSM" David Melville   This is not an email and hasn't been checked for viruses by any half-arsed self-promoting software.

Cursitor Doom <curd@notformail.com>: Jun 10 06:32PM > If it is mechanical, it may be jammed on something caught in the gears, > or perhaps the gears have slipped. Otherwise, you may need to replace > the part.   If the main bearing is badly worn, then those teeth can come out of mesh. I've had this with a Trio TS530s. It's a simple matter to reset the gears, but if the worn bearing isn't dealt with beforehand it'll come out of mesh again pretty quickly.           -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

Lucifer <LuciferMorningstar@bigpond.com>: Jun 11 02:10PM +1000 On Mon, 10 Jun 2019 18:32:07 -0000 (UTC), Cursitor Doom >I've had this with a Trio TS530s. It's a simple matter to reset the >gears, but if the worn bearing isn't dealt with beforehand it'll come out >of mesh again pretty quickly.   It works properly up to about 800Khz. Further rotation of the dial is possible but the frequency on the digital readout and the part around the dial do not go any higher. Hopefully when I take the cover off I will be able to fix it.

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