- suggestions for setting up a dosimeter charging system - 2 Updates
- Screw size for MacBook Pro - 7 Updates
- 7805 regulator source? - 1 Update
| Juan S <none@anytime.net>: Jan 17 09:34AM -0500 I am in the process of trying to set up a reliable dosimeter charger system for a relative. The type of dosimeter I'm speaking of are the pen looking devices that are zeroed after exposure to radiation so that they can be reused over and over agin. There are a couple of types of "chargers" used for this process: https://pim-resources.coleparmer.com/item/l/radiation-alert-the-charger-radiation-dosimeter-charger-8192200.jpg https://i.ebayimg.com/images/g/9X0AAOSwcm5fNxcf/s-l1600.jpg I personally own the first type above (the coleparmer unit). It doesn't need power, and uses a piezoelectric element that is pressured to produce charging, then can be bled off until the dosimeter is zeroed. However, I got mine in a trade deal with a bunch of other equipment, so it was essentially free. What I like most about it is that it doesn't need any kind of power source for charging dosimeters unlike the second yellow one above that needs a 1.5V battery. It is the type I own that I had hope to obtain for a relative too, but at the prices I see them go for, it is out of the question! So, that leaves the yellow ones that use a 1.5V battery. I do happen to own a couple of those, but find them much harder to use than the trigger charger. I was considering modifying it so that it wouldn't have to use a 1.5V battery. Only a bendix 643 (CDV 750 model 1) used a pump charger that must have been similar to the trigger charger I use, but I have yet to see one in the used marker. How would you go about modifying an existing charger so no battery would be needed? Thanks in advance for your help. |
| "Peter W." <peterwieck33@gmail.com>: Jan 17 07:50AM -0800 https://www.amazon.com/Jordan-Radiological-Dosimeter-Chargers-Bendix/dp/B076746ZG8 I actually have this set (only four pens, however). It came as a set with a geiger-counter that I snagged at a flea. If you want to make the charger stationary, it is simply a matter of delivering the proper DC voltage - which I dimly remember is supplied by one D-sized cell in the container. And as these were based on conventional Leclanche cells, that would be 1.56 volts DC. That should not be too difficult. But, of course, you would need some power from some source. That, sadly, is the nature of those beasts. Peter Wieck Melrose Park, PA |
| David Farber <farberbear.unspam@aol.com>: Jan 16 04:44PM -0800 I'm trying to disassemble a MacBook Pro, model number A1989, to remove the hard drive. The screwdrivers I have do not mach the shape or size of the bottom panel case screws. I believe the screws are pentalobe type. Does anyone know the exact size screwdriver that will fit these screws? Thanks for your reply. -- David Farber Los Osos, CA |
| Clifford Heath <no.spam@please.net>: Jan 17 12:56PM +1100 On 17/1/22 11:44 am, David Farber wrote: > the hard drive. The screwdrivers I have do not mach the shape or size of > the bottom panel case screws. I believe the screws are pentalobe type. > Does anyone know the exact size screwdriver that will fit these screws? I don't have the right pentalobe bit, but I find that a 1.4mm flat blade miniature screwdriver gets them undone ok. Ugly, but it works without mangling the screw, if you use a bit of downforce. Not kind to the driver, but those can be sharpened or replaced. Clifford Heath. |
| David Farber <farberbear.unspam@aol.com>: Jan 16 06:19PM -0800 On 1/16/2022 5:56 PM, Clifford Heath wrote: > mangling the screw, if you use a bit of downforce. Not kind to the > driver, but those can be sharpened or replaced. > Clifford Heath. Hi Clifford, I don't want to risk mangling the screw head unless it's a last resort type of thing. Thanks for your reply. -- David Farber Los Osos, CA |
| Clifford Heath <no.spam@please.net>: Jan 17 03:18PM +1100 On 17/1/22 1:19 pm, David Farber wrote: > Hi Clifford, > I don't want to risk mangling the screw head unless it's a last resort > type of thing. Try it. You'll find that the screwdriver is much more vulnerable than the screw, and even if something does yield, the pentalobe is still structurally intact. I've done it multiple times on my Macbook with no visible damage to any of the screws. CH. |
| whit3rd <whit3rd@gmail.com>: Jan 16 09:12PM -0800 On Sunday, January 16, 2022 at 4:44:40 PM UTC-8, David Farber wrote: > the hard drive. The screwdrivers I have do not mach the shape or size of > the bottom panel case screws. I believe the screws are pentalobe type. > Does anyone know the exact size screwdriver that will fit these screws? The sizes are not standard, really. So, usually pentalobe drivers are sold in sets of two or three sizes. 1.2mm pentalobe was the label on the one that fits my A1370 Air. Some come labeled "P2" "P5" "P6" or "0.8mm". "P5" and 1.2mm are the same. I'd not recommend trying non-fitting drivers, those screws are stainless and generally soft enough that a steel driver can hurt them. |
| David Farber <farberbear.unspam@aol.com>: Jan 16 09:21PM -0800 On 1/16/2022 8:18 PM, Clifford Heath wrote: > structurally intact. I've done it multiple times on my Macbook with no > visible damage to any of the screws. > CH. After some further research, this has all become moot because I found out the "hard drive" is merely a couple of chips *soldered* onto the logic board. Since this particular computer has a bad display, it could be connected to an external monitor and then data could be copied to an external drive. https://discussions.apple.com/thread/250143892 Thanks for your reply. -- David Farber Los Osos, CA |
| David Farber <farberbear.unspam@aol.com>: Jan 17 01:47AM -0800 On 1/16/2022 9:12 PM, whit3rd wrote: > "P5" and 1.2mm are the same. > I'd not recommend trying non-fitting drivers, those screws are stainless and > generally soft enough that a steel driver can hurt them. Thanks for the detailed information on the tools. As it turns out, there is no hard drive in this model. There are memory chips soldered directly onto the logic board. -- David Farber Los Osos, CA |
| whit3rd <whit3rd@gmail.com>: Jan 16 12:41PM -0800 On Thursday, January 13, 2022 at 9:47:12 AM UTC-8, Peter W. wrote: > Please don't get me wrong - I have pulled many gems 'off the curb'... And I am not above salvaging parts, either. But I will not go diving for a random bit of electronics when I know that I will be able to find a genuine part at a small cost that is both new and warranted. If the need is just a 5V regulator, an auto accessory stepdown regulator is available at my local dollar store (USB charge point); no order/deliver delay. As for 'warranted', that's a meaningless consideration for little nuts-and-bolts small change items. I'm not going to pursue a warranty, they're expendable. Instead, order/stock a few extras... |
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