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Thread: DSX12V: 12V in 12V out 10 AMPS!

  1. #81
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    Quote Originally Posted by ryanrs
    Oh please. 4 transistors, a coil, and a 24 pin SSOP? It's got "app note" written all over it. Of course, that's not a bad thing. But let's not ring up the patent office just yet, Mr. Cuk.

    Nobody's going to fab a board for that SSOP when they can just buy a finished unit for $70. And a real competitor just purchase one of your units anyway.

    So how 'bout it zootjeff? Will you divulge the part number or do we have to flip through this month's issue of _Power_Electronics_?

    To rushnrockt and MrPerfectionest: it's not a full bridge, it's not a SEPIC, and it's not a senior design project.
    Mmm, yeah, amazing dude, you sure you are not a friend Josh The Pilot? Anyways genius, it's obvious it is not a freaking "senior design project."
    While from personal experience I can say ZootJeff is a bit too secretive for no reason (to a point of being unpolite), but if you believe it to be so easy to make, go ahead and make one yourself.

    P.S. Yeah, good punch line there, "Mr. Cuk"
    I have found you an argument; I am not obliged to find you an understanding.

  2. #82
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    Quote Originally Posted by ryanrs
    Also, consider that the cheap, rapid-turnaround pc boards suck for fine pitch surface mount. You really want to have a solder mask.

    Even if zootjeff offered his CAD files free on his website, you'd still need to produce at least 3 units to come out ahead. That assumes you make zero mistakes and everything works the first time.
    If it's no big deal why do you want to know so bad? I guess if Pepsi published the recipe for Coke, no one would really care right? Especially Coke, thatís why it is no big secret.
    MPEGBOX - Plexiglass Computer
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  3. #83
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    Quote Originally Posted by zootjeff
    If it's no big deal why do you want to know so bad? I guess if Pepsi published the recipe for Coke, no one would really care right? Especially Coke, thatís why it is no big secret.
    It's more like the recipe for chocolate chip cookies. If someone asks, just tell them the recipe is printed on the back of the bag. You don't have to give out you super-special variation. But don't claim the whole thing is some huge secret.

    Part of the issue relates to the nature of modern power supply controller chips. By design, these chips are optimized for a very specific application. This makes the chip much less adaptable to other circuits. As a result, most circuits using the chip are very similar. For comparison, the LM723 linear controller can be used in a huge variety of circuits. It's a tradeoff between versatility and simplicity. By placing more functionality inside the chip, the final circuit becomes simpler, but less flexible. Naturally, if the simple solution solves your problem, you should use it. But don't be get upset if your competitors use a very similar circuit.

    Anyway, it appears the DSX12V uses the Linear Technologies LTC3780. Zootjeff's circuit appears to be a variation of the circuit shown on LTC3780 product page. See: http://www.linear.com/pc/productDeta...2,C1116,P10090. The inductor looks like a 2uH Coilcraft SER2009, but I'm not sure.

    BTW, the circuit in the datasheet shouldn't be connected directly to a vehicle's +12 rail without some protection circuitry. A car's power supply is a dirty, dirty thing. It would suck to have your computer destroyed the first time you start your car. Or when you get a jump start. Or 3 years down the road when your alternator fails.

    Zootjeff, you may be curious why I chose to scrutinize your product. Especially since I'm not a regular poster on this forum. About a month ago, someone posted the specs of the DSX12V to sci.electronics.design and asked if the numbers were reasonable. The general consensus was that the specs were legit, but the efficiency was probably a bit overstated. I came across that thread a couple days ago that's what brought me here.

    The guy that posted to sci.electronics.design was right to question your specs. The auto electronics industry tends to play fast-and-loose regarding product specifications. And by fast-and-loose, I mean egregoius lies. Car audio manufacturers, in particular, are notorious liars. The poster's skepticism was certainly warranted given the reputation of the industry. Zootjeff, as an engineer in the industry, I'm sure you've seen some of this. The level of bull**** can make it very hard for an honest product to noticed.

    So I took a look at the DSX12V design and determined what controller was used. I also determined Rsense, L, and Cout. Plugging these values into the equations on the LTC3780 datasheet, I feel the specs Zootjeff quoted are completely reasonable. Contrary to the consensus on sci.electronics.design, I don't think Zootjeff inflated his specs at all. In particular, the following specs are very reasonable: For Vin=8..16v and Iout=0.5..10A, 100mV ripple and 95+% efficiency. For Vin=13..14v and Pout=85W, 97.5% efficiency. These figures assume Zootjeff didn't use crappy mosfets or output capacitors. I suppose omitting the two schottky diodes will reduce efficiency 1-2% but it's hard to know precisely.

    One of the sci.electronics.design posters speculated that measurement errors likely inflated the efficiency figures. However, Zootjeff's Tektronics TDS3000 series 'scope is a really nice instrument and would have no problems measuring RMS power. Use math mode to calculate the instantaneous power waveform, then use the measurement utility to calculate the RMS power. (Can you tell I have the same 'scope?)

    I hope no one thinks I've been ****ting on design of the DSX12V. It appears to be a great product and I don't doubt the specs. I just think Zootjeff's secrecy isn't appropriate, given the nature of the design.

  4. #84
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    Quote Originally Posted by rushnrockt
    Anyways genius, it's obvious it is not a freaking "senior design project." .... P.S. Yeah, good punch line there, "Mr. Cuk"
    Sorry about that. I was trying to be funny, but I missed the mark. I didn't intend to be that snarky when I wrote it. I put the Cuk bit in because I thought it'd be funny. I cited _Power_Electronics_ because this month's issue includes a blurb about the LTC3780. Sorry for being an ***, I hope you don't take offense.

  5. #85
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    Quote Originally Posted by ryanrs
    Sorry about that. I was trying to be funny, but I missed the mark. I didn't intend to be that snarky when I wrote it. I put the Cuk bit in because I thought it'd be funny. I cited _Power_Electronics_ because this month's issue includes a blurb about the LTC3780. Sorry for being an ***, I hope you don't take offense.
    Alright, this makes more sense now. It would've helped if you explained everything at the beginning.
    I was actually looking at the LTC3780 for the purposes of what I am doing, and came to a conclusion that:
    a) hmmm, it does look like zootjeff's setup (not like I am planning on competing)
    b) my senior project advisor is a dumbass and i might need to reconsider what i am doing for senior project (i didn't know what I was getting into at the beginning)

    So yeah, thanks for clarifying everything, Mr. Cuk.

    P.S. You must realize that you are now in danger of being bugged by a desperate EE student (namely me). That's what you get for showing up j/p
    I have found you an argument; I am not obliged to find you an understanding.

  6. #86
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    Shipping Pre-Orders

    Those of you who pre-ordered the DSX12V for $80 with paypal will be recieving your units shortly. They will ship on Tuesday May 10th.

    Thanks,

    -Jeff
    MPEGBOX - Plexiglass Computer
    www.mpegbox.com

  7. #87
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    I recieved my unit Friday and tested it this weekend.

    It works wonderfully. My PC (which draws about 8 AMPs when POSTing, and then 4-5 while running) has no issues at all, even under torture loads like cranking. Combined with the micro shutdown controller, my electrical needs have been met. Now to finish the case, run the wires permanatly, and install the LCD.

    Thanks a lot Jeff!

    Scott

  8. #88
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    Quote Originally Posted by foltster
    I recieved my unit Friday and tested it this weekend.

    It works wonderfully. My PC (which draws about 8 AMPs when POSTing, and then 4-5 while running) has no issues at all, even under torture loads like cranking. Combined with the micro shutdown controller, my electrical needs have been met. Now to finish the case, run the wires permanatly, and install the LCD.

    Thanks a lot Jeff!

    Scott
    What kind of system are you running?

    Glad it's working for you!

    -Jeff
    MPEGBOX - Plexiglass Computer
    www.mpegbox.com

  9. #89
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    I think we got a testimonial

  10. #90
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    Quote Originally Posted by foltster
    I recieved my unit Friday and tested it this weekend.

    It works wonderfully. My PC (which draws about 8 AMPs when POSTing, and then 4-5 while running) has no issues at all, even under torture loads like cranking. Combined with the micro shutdown controller, my electrical needs have been met. Now to finish the case, run the wires permanatly, and install the LCD.

    Thanks a lot Jeff!

    Scott
    What are your PC Specs? Details!
    -Jesus- King of Kings Lord of Lords

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