Those are mini-ATX, not ATX. They will not deliver anything close to 1000 Watts. Besides, even if they did, the equipment would not take it. It wou ld have to be down-converted on every string. With strings numebering in t he 100s, that is a tall order, indeed.
Those are not full-sized ATX supplies. They are mini-ATX for ITX machines. None of them are anywhere near 1000 Watts.
I might be able to get away with sing a 1N5821G Schottky diode for D2 an d moving it back next to the input fuse. That will of course alleviate the reverse polarity vulnerability. It is awfully tight, however. Assuming t he main supply is delivering a full 12V, the current should be no more than 1.3 amps. At that current the voltage drop across the diode should be .4V or less. That leaves us with 11.6V at the charging circuit input.
I could employ an FMMT720 for Q6, in which case the CE saturation voltag e for an emitter current of 300mA or less is .1V max. The voltage at the i nput to X1 would then be no less than 11.5V.
The 1N4148 diode should reliably have a forward bias voltage of between
0.6 and 0.7V. Assuming the worst case of .7V, then the charging voltage at F2 can be as high as 10.8V. That yields a very thin headroom between the terminal voltage of a fully charged 9.6V NiMH battery and the maximum avai lable charging voltage. It may be serviceable, however. Note the power su pply must absolutely deliver no less than 11.8 volts or so.The circuit is quite serviceable with a power supply input of up to 18V. I will play with this when the prototype boards come in. They should be here in a couple of weeks.
That is certainly one way of providing reverse polarity protection.
Another would be using a FET or since X1 is already protecting Q6 you just need to protect U1 and the IRED of X1. You could use a 1N4148 type of diode in the ground lead to U1 and X1 and then to protect the inputs of U1 insert resistors in both input leads, more parts but all low power cheap ones.
piglet
BTW your schematic doesn't show a supply bypass cap for U1 - TL071 might be tame without one but op-amps can do bizarre things without.
piglet
Point well taken. I've never had any problems with a TL071 in a unity gain application, but the addition of Q6 might give it indigestion.
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