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  • DiiK commented on Salazar2's forum topic 12V DC to 12V AC?

    This assumes someone is willing to accept the 20-30% power waste that a setup like this would create. I am personally looking for the normal 95% or better efficiency found in the small boost/buck converters made in China.

    Are dual transformers necessary? I would like a 6VAC output with a single transformer. No part number I can see here on the transformer but does a single isolation transformer exist in a 2:1 ratio with the 12VAC CT input on one side and with that ratio, then would produce a 6VAC output? I need about a 3A 6VAC source which is isolated from a 12VDC power source. It looks like the driver you have created will work but the transformer is the mystery. Again looking for an appropriate 3A 2:1 wound transformer without the requirement as here to step up to 220V and back down if possible. This of course could be addressed with a cheap 12V to 120VAC low wattage inverter which powers a standard wall transformer to reduce the 120VAC back down to 6VAC. I would estimate a 20-30% power l…

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    Are dual transformers necessary? I would like a 6VAC output with a single transformer. No part number I can see here on the transformer but does a single isolation transformer exist in a 2:1 ratio with the 12VAC CT input on one side and with that ratio, then would produce a 6VAC output? I need about a 3A 6VAC source which is isolated from a 12VDC power source. It looks like the driver you have created will work but the transformer is the mystery. Again looking for an appropriate 3A 2:1 wound transformer without the requirement as here to step up to 220V and back down if possible. This of course could be addressed with a cheap 12V to 120VAC low wattage inverter which powers a standard wall transformer to reduce the 120VAC back down to 6VAC. I would estimate a 20-30% power loss for a setup like that. I would be looking instead toward a design leaning more toward the 95% efficiency of the boost/buck converters that are being produced now in China.

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  • I think the charging current must be AC because often the phone will sit in the cradle either way with the earpiece facing in our out and thus DC power if you place the phone in the cradle backwards would not charge the phone if you have a DC source, no matter how you jerry rig the voltage because the rectifier is not a 4 way. Powering it instead with a low-voltge AC source means that you can set the phone in the cradle facing either direction. I recall some with cradles that work both ways (earpiece facing toward the wall or out into the room) so I assume this is the reason. Nevertheless no DC converter will ever work with my setup because I have a power system consisting of a single large 12VDC battery powered by a solar charging array. I use a Linksys ATA (VOIP adapter) SPA -2…

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    I think the charging current must be AC because often the phone will sit in the cradle either way with the earpiece facing in our out and thus DC power if you place the phone in the cradle backwards would not charge the phone if you have a DC source, no matter how you jerry rig the voltage because the rectifier is not a 4 way. Powering it instead with a low-voltge AC source means that you can set the phone in the cradle facing either direction. I recall some with cradles that work both ways (earpiece facing toward the wall or out into the room) so I assume this is the reason. Nevertheless no DC converter will ever work with my setup because I have a power system consisting of a single large 12VDC battery powered by a solar charging array. I use a Linksys ATA (VOIP adapter) SPA -2102 that apparently (internally) grounds one of the phone line wires to the power supply line negative terminal internally (5VDC powers the SPA-2102) and therefore if you also power the phone off for example an additional 12VDC buck converter which produces 6.5VDC, then this wreaks havoc by grounding one side of the phone electronics to your 12VDC solar battery while the SPA2102 if powered by a 12VDC to 5VDC buck converter also grounds a random other side of the phone wire. So if you attempt to power both the VOIP telephone adapter device from the LAN cable of an Internet connection and a rechargeable portable conventional "portable" telephone that plugs into the ATA (VOIP unit) and they both are powered by buck converters while attached to the same battery and 12VDC power supply, the combo will never work even if the phone would somehow work from increased DC voltage instead of the 6.5VAC it was designed for.Therefore you absolutely need some type of oscillating or actually pulsing DC source driven by the 12VDC battery that could be run into a low ratio transformer to isolate the two power sources.as well as provide a DC pulse converted to a rough AC one to supply an input to (perhaps) a 1:1 transformer that would ultimately supply that low AC voltage needed for the rechargeable phone, Indeed it would be a very messy but usable "almost" sine wave to supply the AC input demand of that portable phone. So that's the circuit I continue to look for to power the portable phone with something sent through an isolation transformer to deliver the needed 6.5VAC phone charging power supply and in the process not physically ground any of the internal circuitry of the phone.

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  • The web has certainly exposed a lot of things to us, hasn'tit?. It really freaks you out sometimes when you discover that youmay be the only one on this earth to have curiosity about a particular area ortopic. Talking about a strange feeling, now that is one!So I say don't feel too lonely. I have also searched for a solutionto this issue for a couple of decades now and thus I found your query todayafter again dragging out the idea of using a portable phone running off 12VDCand a buck converter . I see we’re bothestill waiting for someone to “crack thenut”. Reason no one has every divedinto resolving this is a) the technology is quite stale and b) until the adventof solar, not that many people had a desire to power things directly ofbatteries or some DC source. During the firstit…

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    The web has certainly exposed a lot of things to us, hasn'tit?. It really freaks you out sometimes when you discover that youmay be the only one on this earth to have curiosity about a particular area ortopic. Talking about a strange feeling, now that is one!So I say don't feel too lonely. I have also searched for a solutionto this issue for a couple of decades now and thus I found your query todayafter again dragging out the idea of using a portable phone running off 12VDCand a buck converter . I see we’re bothestill waiting for someone to “crack thenut”. Reason no one has every divedinto resolving this is a) the technology is quite stale and b) until the adventof solar, not that many people had a desire to power things directly ofbatteries or some DC source. During the firstiterations of portable phones, changers were often rated at 6VAC to 9VAC. Today many cordlessphones run on power supplies stamped as 6VDC but where these differ from traditionalsupplies is a) often printed on the chargeris a pulsing DC graphic symbol (as an oscilloscope will also demonstrate) and b)apparently in order to keep costs down and thus provide the pulse , the filter capacitor is removed to best providea cheap solution. AC or pulsed, thephone circuitry somehow sorts it out so that the handset will still charge withit sitting in the cradle facing either the front or back of the room. Still this design really doesn’t make sensesince in our “DC only component world” a bridge rectifier could be added to thehandset and the diode drop in voltage would still not significant to haltcharging of a standard 3.7VDC handset battery. So my guess is here that the mfgs. simplymake them this way because they always have done it this way and it’s easier tostrive for a minimum act of plagiarism of past accomplishments rather thancoming up with something entirely new.My own situation? I am retired and travel crosscountry extensively in my RV where I am trying to also design a “no inverterneeded for portable phone” setup. I need to remain with a VOIP service that’s transparent all across the continent,cell carrier to carrier and country to country. So what I elected to do is use a LinksysSPA2102 ATA (VOIP device) attached to a conventional wired wall phone and use aservice which gives me a single US number with both voice and text. The VOIP frees me up for elevated antennasetups for data only connections as well. Problem is that each time I again comb the retailers to see if theportable phone technicality has changed enough escape the “AC source needed” , I always discover the same thing, that theyare still locked into this 20 year old technology. A few years after extended experimentation I somehow got oneof the 6VAC portable phones charging of 12VDC with various iterations of buckconverters. But I soon had to curb myexcitement when I made the sad discovery that both my modified portable phoneand the Linksys ATA both had opposite polarities of the 12V supply source tiedinto the actual phone line and at that point I started blowing fuses. So atthat point I just gave up.

    Just a quick net and summary followup of my longer full story - basically the isolation of the power supply transformer is often a positive in keeping any voltage potential (particularly grounding one side of the phone line) out of your circuit so don't spend too much effort on a design only to discover you've also managed to ground (or positive!) one side of the phone line. The regular POTS land line will go nuts as well as VOIP ATAs with either the telephone ring or tip grounded. In many ways it seems you can't get there from here. In short be prepared to add an isolation transformer to any circuit you design as a DC to AC power supply if the objective is to power an recent-technology cordless phone from DC and attach to PTS. You don't want to be disappointed at the end.

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  • Direction of positive electrons? All electrons are negative. Positive atomic particles are called protons but only electrons (negative particles of atoms) flow in an electric circuit. Realizing that our culture is to accentuate the positive, eliminate the negative and don't mess with mister in-between, we must all relinquish our prejudices and realize that all of electricity consists of only the negative portion of the atom being pulled and tugged down the entire path of connectivity, while each electron knocks other negative particles of other atoms in, around and about in a forceful manner. Incidentally, the proton and the neutron form the atom's nucleus and the electron spins around the outer edge of that cluster. Electrons in diodes flow the direction from the arrow point into…

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    Direction of positive electrons? All electrons are negative. Positive atomic particles are called protons but only electrons (negative particles of atoms) flow in an electric circuit. Realizing that our culture is to accentuate the positive, eliminate the negative and don't mess with mister in-between, we must all relinquish our prejudices and realize that all of electricity consists of only the negative portion of the atom being pulled and tugged down the entire path of connectivity, while each electron knocks other negative particles of other atoms in, around and about in a forceful manner. Incidentally, the proton and the neutron form the atom's nucleus and the electron spins around the outer edge of that cluster. Electrons in diodes flow the direction from the arrow point into the wider part of the arrow, or for the banded diode they flow into the band and come out the other (bandless) end. The diode is a one way electron valve. The battery (-) is the source of electrons and the battery (+) is the absence of electrons, so therefore electrons flow toward the positive terminal via the external (to the battery) circuit. Negative (always) electrons flow from a battery minus to the battery plus. They flow into the diode symbolic arrow tips and bands and come out the other end of the diode, and only flowing one way.

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