- suggestions for setting up a dosimeter charging system - 3 Updates
- Screw size for MacBook Pro - 3 Updates
- want to replace electret mic with one of these - 3 Updates
| Jeff Liebermann <jeffl@cruzio.com>: Jan 20 02:02PM -0800 On Tue, 18 Jan 2022 17:19:39 -0800, dplatt@coop.radagast.org (Dave Platt) wrote: >lethal to humans in a relatively short amount of time (minutes to >weeks). They're "no, you really don't want to be here, get the hell >away" devices, just like the dosimeters. There are actually two similar looking boxes in the kit. (I can provide a photo of the kit as soon as I find the box). The C DV-700 geiger counter, which uses a Geiger-Muller tube, and the CD V-715, which is an ionization chamber: <https://www.ebay.com/itm/163254194417> (I paid $35 for the entire kit at a local garage sale in 1985, before Chernobyl. Nobody believes me today). <http://www.civildefensemuseum.com/cdmuseum2/radkits/cdv700.html> <http://www.civildefensemuseum.com/cdmuseum2/radkits/cdv715.html> The photo also shows the quartz wired dosimeters and readers. The geiger counter is for fairly low radiation levels. The ionization chamber is for fairly high levels. I've been told that if I need to use the ionization chamber device, I'm already dead. >They don't respond well to low levels of radiation (background, NORM, >uranium glass, Fiesta ware, etc.). Yep. The entire range of the geiger counter on X100 is about 1/2 the first division of meter on the ionization chamber. <http://www.civildefensemuseum.com/cdmuseum2/supply/radkits.html#compare> >very sensitive to moisture. As I recall, they're supposed to be >"baked" periodically to make sure they're dry, and then stored sealed >in plastic with a dessicant pack. Nope. The ionization chamber is hermetically sealed (sealed by a hermit): <https://www.survivalmonkey.com/resources/victoreen-cd-v-715-instruction-and-maintenance-manual.267/download?version=268> "The ionization chamber is hermetically sealed to eliminate changes in sensitivity due to changes in air pressure resulting from altitude changes, temperature changes, and moisture effects". (Pg 3) However, I have seen problems with the phenolic paper PCB used in most early units. The PCB absorbs enough moisture to cause high resistance shorts. A few minutes in a toaster oven usually solves the problem. If I see some flux left on the PCB from a previous repair, I clean it off with water and alcohol separately, and then coat the area with some manner of conformal coating or high-voltage corona dope. >you mention... in an actual fallout zone, Geiger counters and >scintillation detectors will probably saturate and read low or >zero. Today, methinks that some of the higher end radiation survey meters have an PIN diode gamma ray detector for the higher doses: <https://www.ssdi-power.com/products/special-devices/radiation-detector-pin-diode/spd9441.html> <https://www.ssdi-power.com/media/pdf/RC0130B.PDF> <https://www.ssdi-power.com/media/sp_pdf/AN2011-01_Radiation_PIN_Diode.pdf> Sensitivity is marginal, but it doesn't saturate at higher doses. At those high levels, it's use is mostly as a dosimeter, not a disintegration counter. <https://www.maximintegrated.com/en/design/technical-documents/app-notes/2/2236.html> etc... -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558 |
| dplatt@coop.radagast.org (Dave Platt): Jan 20 02:50PM -0800 In article <r4kjuglg5hcoq6d508b969h1bk8rq5id5h@4ax.com>, >geiger counter is for fairly low radiation levels. The ionization >chamber is for fairly high levels. I've been told that if I need to >use the ionization chamber device, I'm already dead. Yup... or, at the very least, that you're likely to be radiation-sick for some time. >If I see some flux left on the PCB from a previous repair, I clean it >off with water and alcohol separately, and then coat the area with >some manner of conformal coating or high-voltage corona dope. Even though the chamber itself is sealed, there can be leakage problems if condensation builds up on the area where the probe wire comes out through the glass seal. That insulator, and the high-megohm resistors and the ceramic switch assembly are (according to the manual) all part of the high-impedance circuit. Any contamination here causes problems, and I've seen condensation have that effect as well. I think your approach of an alcohol cleaning, and then good high-Z conformal coating is probably just the ticket. And, yeah, phenolic- paper PCBs are rather on the loathsome side, for a bunch of reasons :-) I've got an old one of these sitting around in a closet. I've been thinking of turning it into something more useful by gutting it, and replacing the ion-chamber system with a small PMT and a plastic scintillation crystal. It still wouldn't be of any real use in a high-fallout zone but it could make a nice, sensitive survey meter for looking for NORM of one sort or another. |
| Jeff Liebermann <jeffl@cruzio.com>: Jan 20 03:07PM -0800 On Thu, 20 Jan 2022 14:02:31 -0800, Jeff Liebermann <jeffl@cruzio.com> wrote: >disintegration counter. ><https://www.maximintegrated.com/en/design/technical-documents/app-notes/2/2236.html> >etc... Also, you use the CMOS sensor in a smartphone as a radiation detector: "The suitability of smartphone camera sensors for detecting radiation" <https://www.nature.com/articles/s41598-021-92195-y> Sensitivity is worse than the PIN diode, but either will work in a high radiation environment. You can also obtain organic plastic scintillating slabs: <https://www.crystals.saint-gobain.com/radiation-detection-scintillators/plastic-scintillators#> Just add a photomultiplier tube. <https://www.hamamatsu.com/us/en/product/optical-sensors/pmt/index.html> -- 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>: Jan 20 01:12PM -0800 On Wed, 19 Jan 2022 17:57:44 +0000 (GMT), mjb@signal11.invalid (Mike) wrote: >He also links a lot of the specific tools needed to open/service >Macbooks etc. on most of his board-repair related YouTube videos :- >https://www.youtube.com/user/rossmanngroup/videos Thanks. I found that MacBook A1989 link at: <https://repair.wiki/w/A1989_2018_13%E2%80%9D_Touchbar_MacBook_Pro> However, no disassembly instructions or tool specs. Still, quite useful for troubleshooting and component level repairs. -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558 |
| David Farber <farberbear.unspam@aol.com>: Jan 20 02:08PM -0800 On 1/20/2022 1:12 PM, Jeff Liebermann wrote: > <https://repair.wiki/w/A1989_2018_13%E2%80%9D_Touchbar_MacBook_Pro> > However, no disassembly instructions or tool specs. Still, quite > useful for troubleshooting and component level repairs. From this detailed disassembly video, https://www.youtube.com/watch?v=_l5SFWA69I0 The tools needed in order of disassembly are: 1)Pentalobe tool of unknown size for bottom panel screws 2)T4 3)T5 4)T6 5)Pentalobe 2 The problem here is that the video does not explicitly say which size pentalobe tool is used to remove the bottom panel screws. When it comes to removing the Wi-Fi screws, the video again says the screws are pentalobe 2. Does that mean P2 or PL2? Another video gives more specific information when the size in millimeters is given along with the P(L) size. That is very helpful. https://www.youtube.com/watch?v=dsYsCrOreHo Wikipedia has a good chart which explains how the same sized screw can have *four* different names for one specific size. https://en.wikipedia.org/wiki/Pentalobe_screw After reading all the information about these disjointed standards for these pentalobe screws (and explained previously by whit3rd further back in this thread), what makes the most sense to me is to make sure you confirm the correct screw size with the measurement in millimeters of the screw. For example say, "Pentalobe screw size 1.2mm," not, "Pentalobe 5." On a side note, there seems to have been a successful lawsuit against Apple for their faulty displays. https://www.ifixit.com/News/16943/macbook-pro-flexgate-repair-program Thanks for your replies. -- David Farber Los Osos, CA |
| mjb@signal11.invalid (Mike): Jan 20 10:15PM In article <drjjuglu39iac5cm3pgiep760c3ork98lo@4ax.com>, ><https://repair.wiki/w/A1989_2018_13%E2%80%9D_Touchbar_MacBook_Pro> >However, no disassembly instructions or tool specs. Still, quite >useful for troubleshooting and component level repairs. Tools :- If it wasn't linked on the description of the YT "board repair" video you looked at, some clues here -- lots of Torx and Triwing and Pentalobe to keep people out. https://store.rossmanngroup.com/soldering-diy/helpful-tools-extras/screwdrivers.html Looks like Pentalobe PL4 for MacBooks ... They've been doing this crap since the days of the Apple Mac, needing a "special" long, thin Torx to reach the ridiculously deep-buried screws! Of course, a standard 1/4" "bit set" won't work, because it's down a deep recess that is too narrow to get a "bit set" down. Real screwdriver, or go home! :( -- --------------------------------------+------------------------------------ Mike Brown: mjb[-at-]signal11.org.uk | http://www.signal11.org.uk |
| Juan S <none@anytime.net>: Jan 20 12:34PM -0500 I have a small transmitter that I use for monitoring my property. It has a sensitive electret mic that feeds the transmitter, but the problem was that it does not have AGC, which is desired due to loud sudden disturbances that sometimes occur. The system has 26 dB gain already, so anything loud coming over the receiver blasts me out of my chair. I recently came across these: shorturl.at/jwCZ0 I came across a video where the module was installed into the microphone of a transmitter to allow increased audio gain and thought it might be perfect for my situation too. In the video, he mentions the tremendous gain increase, but uses a variable resistor on the output to reduce it which is what I would do as well. I do have a question though: since I am replacing an existing electret which already has voltage for its bias, what would I need in the audio line going from transmitter to the now module, a bypass capacitor in the positive line leading from transmitter to module? Assuming so, what value and type? Thank you. |
| "Peter W." <peterwieck33@gmail.com>: Jan 20 11:09AM -0800 Link is broken. |
| Juan S <none@anytime.net>: Jan 20 02:20PM -0500 On 1/20/22 2:09 PM, Peter W. wrote: > Link is broken. Try this one: https://tinyurl.com/39xhut3k |
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