- Bipolar PROM replacement? - 2 Updates
- I need an inspection camera - 3 Updates
- Sentry safe solenoid - 1 Update
| John Crane <john_crane_59@yahoo.com>: Jul 03 07:44PM -0500 Just wondering if anyone has repaired a 74S471 Bipolar PROM. These run hot, so I guess it's not surprising they fail. Since they are difficult to find and program, I'm considering replacing it with an EPROM (which I can program), and using only 256 bytes of it. Anyone ever done this? I know the PROMs run faster than the EPROM, but this is a vintage computing project, and the machine runs code from a 2716 just fine. -J |
| Rob <nomail@example.com>: Jul 04 11:22AM +0200 > Anyone ever done this? > I know the PROMs run faster than the EPROM, but this is a vintage > computing project, and the machine runs code from a 2716 just fine. But is the system running code from that 74S471? Sometimes those PROMs were used as glue logic, i.e. to implement a random logic function, like in a PAL or GAL. For that purpose, you need a faster device than for running code. |
| Jeff Liebermann <jeffl@cruzio.com>: Jul 03 10:31AM -0700 On Fri, 2 Jul 2021 09:03:44 -0700, Frankly <Frankly@Frankly.COM> wrote: >But not the usual endoscope. >All endoscopes I know about have a very close and short focus range. >I need a focus range more like a webcam. Endoscopes and borescopes usually have a fixed focus and aperture, and therefore also have a fixed field of view. You seem to be looking for a borescope with adjustable focus and possibly aperture. Perhaps mechanical zoom? Such cameras exist, but you won't like the price. Look for larger borescope cameras like sewer pipe inspection, automotive inspection, medical inspection, etc. >I also need 1080P resolution. Why? >I prefer it to work with an Android tablet for the larger screen. >9" screen or bigger. >A Windows tablet will do but is less acceptable due to cost. 1080p (1920 x 1080) is wasted on a small screen unless you're planning to enlarge the image for presentation, printing or publication purposes. I don't see any numbers, such as the size of the hole, magnification, sensitivity, etc, so I can't calculate how the imager DPI (dots per inch) will translate into the viewer DPI. For example, if you have a crude 640 x 480 imager, and upscale that to a 1920 x 1080 screen, you'll have about 3 pixels on the screen, for every pixel on the camera. >Suggestions please. Numbers (specs) please. Also some clue as to what you're trying to accomplish. -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558 |
| Jeff Liebermann <jeffl@cruzio.com>: Jul 03 10:53AM -0700 On Sat, 03 Jul 2021 10:31:16 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote: >example, if you have a crude 640 x 480 imager, and upscale that to a >1920 x 1080 screen, you'll have about 3 pixels on the screen, for >every pixel on the camera. Oops. 3 pixels horizontal and 2.25 pixels vertical is 6.75 pixels on the screen, for every pixel on the camera (imager). -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558 |
| Frankly <Frankly@Frankly.com>: Jul 03 12:42PM -0700 Think of it this way. A Win PC or Tablet (Android) with a wired camera so I can walk and view. With a light at the camera for illuminating the subject if needed. Look under and around things . No WiFi or bluetooth involved. I do not need a tiny camera to stick through a hole, I already have two that are extremely limited in use. One is all in one and the other is a WiFI version which is terrible operationally. I need high res to record what I see on the screen. Frankly wrote: |
| Jeff Liebermann <jeffl@cruzio.com>: Jul 03 10:44AM -0700 On Fri, 2 Jul 2021 04:50:27 -0700 (PDT), Hilda Winkler >Hi group, can someone help please??? I have a Sentry safe #sfw082et, i don't have the combination number.. anyone know how to open the solenoid electronically.?? i tried to apply 6v to red black and green, didn't work. the safe is from a relative who passed away.. any help will be taken seriously You're lying but that's ok. At your apparent level of expertise, you will eventually make a mistake and get caught. Sentry safes are thin sheet metal, plastic and insulation. You can easily open them with an angle grinder or Skill saw: <https://www.youtube.com/watch?v=2guvwQvElA8> The magnet trick usually requires a rather powerful, dangerous, and expensive permanent magnet. Handle it wrong and you will smash your fingers. Not recommended unless you know exactly what you're doing. -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558 |
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