jolshefsky

Member Since: June 1, 2006

Country: United States

Profile

Websites

http://JayceLand.com http://JayceLand.com/blog http://jasondoesitall.com/ http://jasondoesitall.com/bikewith2brains

  • News - Fluke Responds to Tradema… | last month

    Browsing through the comments (but not every single one), while I despise the combination of a Draconian and moronic US Patent and Trademark Office, I do side with Fluke’s rationale of safety.

    I own a few cheap meters. And they work fine as long as you stick to low-voltage/low-power applications. But they are wholly unsuitable for mains-voltage work (e.g. when attempting to troubleshoot any plug-in piece of equipment), or for high-currents (e.g. LiPo battery packs). I’ve become a fan of Dave Jones' video blog and forums, and his teardowns of cheap meters ( http://youtu.be/gh1n_ELmpFI?t=8m56s or http://youtu.be/n3WGaiYF2sk?t=17m43s ) and his own near-death experience with a cheap meter ( https://www.youtube.com/watch?v=Ewyf9mzIfi0 ).

    Basically, you get what you pay for. I think it’s irresponsible and dangerous to hand a novice a cheap meter and let them go to town. I used to take those meters and test mains voltages, and if I happened to have the range set to anything but high-voltage AC, the meter could literally have blown up in my hand, and possibly electrocute me.

    It might be nice if all the cheap meters in were red (a la Harmer Fright), but you just have to look at each one and make sure (a) you’ve got a good brand in your hand, and/or (b) you took it apart and verified High-Rupture Capacity (HRC) fuses, high-voltage isolation slots, and other good design decisions.

    (Alternatively, +1 for a clear case!!!)

  • Product COM-12723 | about 3 months ago

    For what it’s worth, I think the SPL chart should be done in line with other commercial speakers: SPL at 1 meter driven at 1 watt. It won’t be perfect, but at least it’ll be comparable to, say, a stereo speaker. Even if you get a reading for say 2KHz so that the ratio can be calculated and extrapolated would be nice.

  • News - New Product Friday: Actob… | about 4 months ago

    Completely non-snarky: this is an awesome set of products that look to provide a LOT of utility.

    Completely snarky: now a whole new generation of engineers can suffer the indignities of the Imperial (American) system of measurement. All that work, and http://OpenStructures.net/ already defined an excellent metric standard …

  • News - September Caption Contest | about 7 months ago

    Owl your base are belong to us!

  • News - Engineering Roundtable - … | about 8 months ago

    Nice explanation, mostly, but you do need to correct a few things …

    First, car batteries are not sealed lead-acid (typically). They are usually flooded lead-acid batteries known as “starting batteries”. The difference is the lead plates in a starting battery are thinner than in deep-cycle batteries allowing them to deliver a lot of current for a short amount of time.

    Sealed lead-acid (SLA) batteries are what you find in uninterruptible power supplies and such. The difference is they are sealed so you can’t get to the electrolyte (acid) and they won’t spill unlike a flooded battery which will if you tip it on its side. It appears that all new SLA use “absorbed gas-mat” (AGM) which is some kind of fiberglass (fiberglass-like?) material that suspends the acid as opposed to the older gel-style SLA batteries which used a gel to do the same thing. AGM batteries work much more like deep-cycle batteries than gel cells which tended to die if deeply discharged. (I’m skeptical that all the batteries labeled AGM really are — it seems that in just the past few years, every single SLA says it’s AGM, but I suspect new labels for the same old gel cells made in China … so far I haven’t found a teardown test to confirm or refute that suspicion, but I digress.)

    For the same capacity in amp-hours, a flooded deep-cycle battery will weigh more and cost more than a starting battery. And for the same capacity, a SLA battery will cost more than a flooded battery. SLA batteries also come in smaller sizes (

  • Product BOB-11820 | about 10 months ago

    The link to the datasheet on this page doesn’t work, but the one on the single LED does.

  • News - According to Pete - Spect… | about 11 months ago

    If you’ll indulge me (well, if you won’t, then stop reading now, I guess), allow me to add another comment. I also have a disdain for selecting board-level connectors. If I want something substantially smaller than 100 mil headers, I turn to the Mill-Max catalog. After my eyes turn bloodshot from browsing the catalog, drawings, and datasheets for interminable hours, I finally give up and pick some barely-acceptable connector. I go to the usual sources and discover it’s not actually stocked by anybody — or that half is but the other half is not.

    I would love a source for very-small board-to-board interconnects with both mating ends in stock, an option to do SMD myself, and a break-out board that can be used with a 100 mil header or to splice to wires. I mean, the JST-SH is a pretty good start — I may just start making projects with those — but an addition (hint) would be a selection of connector-to-connector cables.

  • News - According to Pete - Spect… | about 11 months ago

    I agree that wire (like rigid circuit boards) is almost always the right answer. But, for example, I think flex-circuit interconnects would have worked with a custom LED strip I was working on with someone else. The idea was a set of 3 boards that would let me drive RGB LED’s using a couple PCA9922 shift registers, but the number of wires we’d need between boards (8 I think) made it too big. (You could nearly indefinitely chain sets of 3 boards together and use it as a big shift register.) Thin wire was fragile and labor-intensive; multi-conductor wire was too big. The goal was to make something wearable without having to worry about failing electrical connections, or without having to hand-wire 8 threads between each board.

    I guess I find that 8-10 conductors would cover 95% of my needs for low-current, flexible connections. When wire isn’t the answer, I don’t have an alternative.

  • News - According to Pete - Spect… | about 11 months ago

    As I keep thinking up possible ideas (and as I keep reading others), the same question pops into my head: “could this be done with rigid boards?” and the answer is always “yeah, pretty much.” (The other theme is flexible sensors, of which, the flexible sensor already is flexible.) Alas, it seems industry has answered the question: flexible circuits are really only useful as interconnects.

    So, okay, that’s my suggestion: interconnects. It would be nice to have an extremely compact interconnect with, say, 2 20-mil “power” traces and 6 or 8 minimum-sized signal traces packed as tight as possible. Get hold of the appropriate terminating connectors and strain reliefs too then make some break-out boards (perhaps the boards could physically integrate a mechanical strain relief). (Oh, and make a way to note “pin-1”!)

    The idea is to offer something that is superior to running wire or using conductive thread. Lengths could be a really short one for just putting two boards back-to-back, like 4 cm, a medium length of 10 cm for connecting between boards inside a project, and maybe 80 cm or so so you could run a cable down the sleeve of a wearable project to a control panel. If double-sided boards are possible, running the signal wires as pseudo-twisted pairs to improve signal integrity would be a cool twist.

    But aside from that, my favorite is the “slap bracelet watch” (or other device) in another comment: it’s the only one where it seems valid to put circuitry on the flexible part due to space constraints. But even then, it could be a regular device with a slap-bracelet as a band.

  • Product PRT-11496 | about 2 years ago

    … and that’s why the girl in the picture has her head down, presumably from lack of water and food for nearly 9 days while she waits for just the internal battery to recharge.

No public wish lists :(