Yep - great explanation! On Sun, Sep 20, 2020 at 4:55 PM Chuck McCown <ch...@wbmfg.com> wrote:
> You have a power supply, say a 6 volt car battery. You connect a pair of > headlights to it with two wires. All is well. > > Now you start building cars. And you are going to wire up the > headlights. Someone points out that you can save some money on wiring by > using the car chassis instead if one of the wires. > > You decide to run the positive connection from the battery to the > headlights with wire and return the current via the car’s chassis. > > Now you have turned a 6 volt electrical system into a +6 volt system. If > you reverse the battery and connect the + side to the chassis and run the > wire from the negative post to the headlights , it will still work fine. > The headlights don’t care. Now you have a -6 volt electrical system. > > The headlights don’t care but the radio does. Most radios expect the > chassis to be negative and their power wire to be positive. You can > “float” the radio by mounting it on an insulator and connecting its power > wire to the car’s chases and the chassis of the radio to the negative wire > going to the battery. A bit dangerous but I have had to do this at times. > > Oh, and the car is an early VW. > > Sent from my iPhone > > On Sep 20, 2020, at 2:19 PM, Steve Jones <thatoneguyst...@gmail.com> > wrote: > > > I still cant comprehend any of this. I'm just dumb when it comes to it > > On Sat, Sep 19, 2020, 2:51 PM <ch...@wbmfg.com> wrote: > >> Yes. >> >> *From:* TJ Trout >> *Sent:* Saturday, September 19, 2020 1:48 PM >> *To:* AnimalFarm Microwave Users Group >> *Subject:* Re: [AFMUG] -48 noob questions (mikrotik) >> >> It's just a simple 48 to 12v converter to feed the mikrotik. I tested >> with a ict +48 supply and the 12v comes out fine, I'm 99% sure it will work >> on the wood bench, and about 90% sure it will work in a rack. >> >> If it was true -48 I would assume the + terminal would be bonded with >> chassis ground? >> >> On Sat, Sep 19, 2020, 12:45 PM TJ Trout <t...@voltbb.com> wrote: >> >>> I think some of my devices have the chassis ground bonded with the >>> negative input terminals, I discovered this >>> because I am running a telecom rectifier shelf designed for -48 on a +48 >>> system because it's floating, but this >>> causes the + output to not be fused, so I practiced arc welding once. >>> >>> Strange, didn't know the 1100 had dc input, but it looks floating though >>> (per specs -48, 12-57 V) >>> >>> >>> >>> >>> On Sat, Sep 19, 2020 at 12:40 PM <ch...@wbmfg.com> wrote: >>> >>>> I don’t think I have ever seen a true +48 load. >>>> >>>> *From:* Ken Hohhof >>>> *Sent:* Saturday, September 19, 2020 1:29 PM >>>> *To:* 'AnimalFarm Microwave Users Group' >>>> *Subject:* Re: [AFMUG] -48 noob questions (mikrotik) >>>> >>>> >>>> Different situation, but I have several sites with 1100ahx4 powered >>>> with +48, even though Mikrotik says they take -48. I suspect you will find >>>> the same to be true on the CCR. >>>> >>>> >>>> >>>> Connect the – terminal to ground and the + terminal to +48, obviously >>>> you don’t want to apply reverse polarity by trying to connect +48 to the >>>> -48 terminal. >>>> >>>> >>>> >>>> I have some ccr1009 and ccr1036 but they are all AC powered, and I have >>>> no ccr1072, so I can’t answer your exact question. >>>> >>>> >>>> >>>> >>>> >>>> *From:* AF <af-boun...@af.afmug.com> *On Behalf Of *TJ Trout >>>> *Sent:* Saturday, September 19, 2020 2:19 PM >>>> *To:* AnimalFarm Microwave Users Group <af@af.afmug.com> >>>> *Subject:* [AFMUG] -48 noob questions (mikrotik) >>>> >>>> >>>> >>>> So I have a handful of ccr1072's that I want to run on our +48v plant, >>>> mikrotik sells a '-48v telecom' power supply and they insist it's not >>>> compatible with +48v. I ordered one for testing and both +/- input >>>> terminals have no reference to chassis ground. I went ahead and applied >>>> +48v and the power supply fired up (no smoke) and when measuring from >>>> chassis ground to the input terminals I see no difference in potential. >>>> >>>> >>>> >>>> Before I shove this into a $3,000 router I wanted to see what I may be >>>> missing here? >>>> ------------------------------ >>>> -- >>>> AF mailing list >>>> AF@af.afmug.com >>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>> -- >>>> AF mailing list >>>> AF@af.afmug.com >>>> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >>>> >>> ------------------------------ >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> >> -- >> AF mailing list >> AF@af.afmug.com >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com >
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