Im curious about the cellular solution I have municipal traffic cams that I can see finding a cellular solution for that wouldnt generate high usage bills or deprioritization for 24x7 streams
On Thu, Jun 5, 2025 at 12:54 PM Adam Moffett <[email protected]> wrote: > You guys would know better than me on the specifics. > > I’m assessing bringing fiber to a bunch of police camera sites which are > currently on cellular. I was looking through their enclosure to assess > putting an ONT in it. They have a Meanwell 48V PSU connected to a terminal > bus. The terminal bus feeds an industrial POE (802.3af) switch, and also > the NO relay which passes power to a single port POE+ injector (802.3at) > which powers the cellular router (Peplink). Finally they have a poe port > from the switch going to a poe extractor/splitter, and the dc output from > that goes to the control terminals on the relay. > > So a poe port on the switch is dedicated to keeping the relay closed so > that the POE+ adapter stays on. And I assume they did that so they could > use the auto-ping reboot. > > I met the customer today and said I thought there was a design issue in > the camera box which would be effectively a time bomb causing sites to go > down. I asked how long it had been running and if they’d had any problems, > and that’s when I learned it only been two months and two sites have > already gone offline. > > Now here’s another possible dumbness: the router says 802.3at on the spec > sheet, but it only needs 11-13 Watts. I think it would have worked on the > regular 802.3af poe ports without all the extra pieces. I thought they > were backwards compatible as long as you didn’t need the extra power. > > > > Get Outlook for iOS <https://aka.ms/o0ukef> > ------------------------------ > *From:* AF <[email protected]> on behalf of Ken Hohhof < > [email protected]> > *Sent:* Thursday, June 5, 2025 11:54:25 AM > *To:* 'AnimalFarm Microwave Users Group' <[email protected]> > *Subject:* Re: [AFMUG] SSR control circuit over voltage > > > Oh, good point, optical isolation. > > I guess double the LED current could burn it out over time. > > > > *From:* AF <[email protected]> *On Behalf Of *Bill Prince > *Sent:* Thursday, June 5, 2025 10:46 AM > *To:* [email protected] > *Subject:* Re: [AFMUG] SSR control circuit over voltage > > > > This going back into my fuzzy memory, but I was on a project where we used > a bunch of SSRs back in ~~ 1990 or thereabouts. My recollection is that > they used an LED internally. That may have just been the brand we were > using at the time. > > bp > > <part15sbs{at}gmail{dot}com> > > On 6/5/2025 7:52 AM, Ken Hohhof wrote: > > So if it’s a solid state relay, there’s probably a silicon controlled > rectifier or triac and no actual relay coil? The control voltage probably > goes through a resistor to the gate of an SCR. > > > > I’m no expert, but I’m guessing they’re fine, especially if it’s been > working all this time. They may even have checked with the component > manufacturer and verified it will work with the higher voltage. The 30VDC > spec might just be a UL thing. > > > > Perhaps it’s like 1N400x series rectifier diodes. Do we really think they > manufacture or test them differently to get 50, 100, 200, 400 volt > ratings? They’re probably all the same diodes just with different markings. > > > > If I were designing something for mass production, I wouldn’t do it. I’ve > certainly seen problems caused by designs that worked but the components > specs were inadequate. Like a manufacturer does a die shrink on a logic > chip and it gets faster and now there’s a race condition. Or a different > manufacturer with an equivalent part gets substituted and now 48VDC is too > much. > > > > *From:* AF <[email protected]> <[email protected]> *On Behalf > Of *Adam Moffett > *Sent:* Thursday, June 5, 2025 7:59 AM > *To:* 'AnimalFarm Microwave Users Group' <[email protected]> > <[email protected]> > *Subject:* [AFMUG] SSR control circuit over voltage > > > > I was looking at pictures of someone else’s enclosure (a camera company). > They have a router powered through a NO solid state relay and they’re > keeping the coil circuit energized continuously. The specs on the relay > say the control voltage is 10-30VDC, but these folks have a 48V power > supply. > > > > I’m not sure how long it’s been in service (finding out today), but I’m > wondering if this is a time bomb. Is that relay going to fail? What’s the > likely mode of failure? One article I saw while googling suggested the > relay might get stuck on….not the worst thing, but it would defeat the > purpose if that’s what happens. > > > > -Adam > > > > > > Get Outlook for iOS <https://aka.ms/o0ukef> > > > > -- > AF mailing list > [email protected] > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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