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101090 discussions

Dumb terminals for daily use today; failure scenarios

by echristopherson＠gmail.com

If one were to use a dumb CRT terminal from the early '70s regularly in this day and age, would it be more prone to hardware failure than if it were kept in storage or just kept to look at but powered off? -- Eric Christopherson

9 years, 7 months

VCF Europe, April 30th - May 1st, Munich + registration for VCF Berlin

by stueberahoo＠yahoo.de

Hi list, the 17th edition of VCF Europe[0] is coming soon! It will take place on April 30th and May 1st in Munich, Germany. Please be aware that the information on the English version of the website might be outdated or less detailed than on the German page, but Google Translate will help. Also the registration for VCF Berlin[1] in October is open now. We are looking for speakers, workshop instructors and exhibitors, both for the regular exhibition and this year's special exhibition on computers and languages. It will be open for visitors on Sunday, 2nd and Monday, 3rd of October, as the 3rd October is a public holiday in Germany, but we are thinking about inviting people to build up on Friday already and using Saturday, 1st of October as a day just for the participants and the community. This way there would be more time to talk and see the other exhibitions. Maybe we could even offer advanced workshops on Saturday. Come and visit us! Ping me if you need a place to stay. Regards, Anke [0] http://vcfe.org/E/index.html [1] http://vcfb.de/2016/index.html.en

9 years, 7 months

Pinging Joe Rigdon

by connork＠connorsdomain.com

Anyone know if Joe Rigdon is still around? Thanks, -Connor K

9 years, 7 months

Voltage regulator with alternate voltage source...

by jrr＠flippers.com

On 04/07/2016 2:18 PM, Bill Sudbrink wrote: > drlegendre wrote: >> Not saying it's going to smoke-out, but it does >> seem like a wonky thing to do. > I disagree about "wonky" let me try with more > diagram and less English: > > (+8) > | > VIN| ceramic cap > |-----][----- > ___|____ | > | 7805 |----------GROUND > -------- | > | | > VOUT|(+5) | > | | > ___|____ | > | LOAD |-------| > -------- > > +8 is not currently available (no pun intended). > I would like to test LOAD without removing 7805 > as it is soldered in place. Is damage to 7805 > likely if alternative regulated current is applied > at (+5) and (+8) is left open? > > Bill S. > > > Yes, you can damage the 7805 - READ the data sheets... Raising the Output Voltage above the Input Voltage: Since the output of the device does not sink current, forcing LM340/LM78MXX Series 3-Terminal Positive Regulators LM340/LM78MXX Series 3-Terminal Positive Regulators the output high can cause damage to internal low current paths in a manner similar to that just described in the ?Short- ing the Regulator Input? section. LM340/LM78MXX Series 3-Terminal Positive Regulato John :-#(# -- John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames) www.flippers.com "Old pinballers never die, they just flip out"

9 years, 7 months

Why do good floppy disks go bad?

by kspt.tor＠gmail.com

The problem with lifetime warranties is that they're not about the lifetime of the owner, and they're not about the lifetime of the product. What it means is "as long as it's a product we're still selling" (except for those cases where it *really* is the lifetime of the product.. in which case it means "the warranty is valid until the product fails").

9 years, 7 months

Mac SE/30 analogue board and PS caps

by dave＠661.org

Does anyone have a list of the capacitors on the analogue board and power supply for a Mac SE/30? -- David Griffith dave at 661.org A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

9 years, 7 months

Voltage regulator with alternate voltage source...

by geneb＠deltasoft.com

On Thu, 7 Apr 2016, Bill Sudbrink wrote: > Maybe I'm overthinking this. If I just put > regulated +5 on the 7805 VIN will it work? > Isn't the minimum input voltage for a 7805, 6vdc? g. -- Proud owner of F-15C 80-0007 http://www.f15sim.com - The only one of its kind. http://www.diy-cockpits.org/coll - Go Collimated or Go Home. Some people collect things for a hobby. Geeks collect hobbies. ScarletDME - The red hot Data Management Environment A Multi-Value database for the masses, not the classes. http://scarlet.deltasoft.com - Get it _today_!

9 years, 7 months

Voltage regulator with alternate voltage source...

by henk.gooijen＠hotmail.com

-----Oorspronkelijk bericht----- From: Bill Sudbrink Sent: Thursday, April 07, 2016 10:38 PM To: 'General Discussion: On-Topic and Off-Topic Posts' Subject: Voltage regulator with alternate voltage source... If you have a circuit which is normally designed to operate with an unregulated supply, through a regulator... say unregulated +8 through a 7805 to a regulated +5 and you want to test it independent of the +8 supply, if you leave the unregulated rail unattached and put +5 switcher straight onto the regulated +5 rail, will you damage the 7805? Clearly the VIN is open, but the ground pin will still be attached. Would this push voltage back through and screw things up? Thanks, Bill S. --------- It is a special situation I have never seen, but I would try to disconnect the output of the 7805 before connecting a foreign +5V to the circuit. It is good practice to have a diode reverse connected from output to input to prevent damage to the 78xx in the case that the output voltage gets higher than the input voltage. Normally that would not happen, but if you have a high capacitance at the output and the load is minimal it could be possible when power is switched off that the input voltage dropped, but due to the big capacitor at the output the output voltage did not yet drop. And then that diode in reverse from output to input comes into play. Now the input is not connected, but GND and the output are ... I would have a look at a data sheet of the 78xx series to see what could happen if the input is not connected, but the output is. So, if possible, simply disconnect the 78xx output lead first. - Henk

9 years, 7 months

Voltage regulator with alternate voltage source...

by wh.sudbrink＠verizon.net

If you have a circuit which is normally designed to operate with an unregulated supply, through a regulator... say unregulated +8 through a 7805 to a regulated +5 and you want to test it independent of the +8 supply, if you leave the unregulated rail unattached and put +5 switcher straight onto the regulated +5 rail, will you damage the 7805? Clearly the VIN is open, but the ground pin will still be attached. Would this push voltage back through and screw things up? Thanks, Bill S.

9 years, 7 months

Front Panels Latest

by rodsmallwood52＠btinternet.com

Hi Guys PDP-8/e A panels now shipping PDP 8/e B panels ship on Friday PDP-8/ f and /m ship on 14th I have some extras of the above if you are quick. Rod (Panelman) Smallwood

9 years, 7 months

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