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stealth17

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Posts posted by stealth17

  4. Eclipse Head Unit Help

    in Electronic Projects Design/Ideas

    Posted


    Hi Jordan,

    There are two possibilities here; one is that this is a crappy player (I have seen others also struggling with diverse problems with this model). Second; the installation is poorly done (unless the car harness has some flaw)!



    Well I think the first is more of the issue. I thought it would possibly be the installation myself too. I Thought about how unclean power is in a car and how much the voltage varies. I mean you will see 12.2v and then 14.4v with ranges in between. So I removed the head unit from the car and hooked it up to a clean, stable bench top power supply and it was the same or worse. That's also when it went into the security mode for the second time. I'm not paying eclipse to unlock it either, it's my cd player and they made it so I can't use it? wtf is that?

    So, are my options really limited here or what?

    Thanks,
    Jordan

  5. Eclipse Head Unit Help

    in Electronic Projects Design/Ideas

    Posted

    I have an Eclipse CD-8455 head unit that I'm having all kinds of trouble with. Sometimes when you turn the car off it will stay on but is frooze. Sometimes it will shutoff and you can't turn it on, it's like it's unplugged, and this is the second time it has gone into security mode and I can't unlock it without paying $25 each time.

    It's out of warranty so Eclipse won't help at all without money for every little thing. They said to send it in at a flat rate or $200 and they will call back if it will cost more. SCREW THAT.

    So, I have it all torn apart and down the the pcb. Shouldn't it come out of Security Mode if I clear the cmos? What should I do with this thing? It's a $400 head unit and I've barely used it. So frustrating, like putting $400 through the shredder.

    Any help is greatly appreciated.

    Thanks,
    Jordan

  6. Need a 5amp 1.25v-2.25v switching schematic

    in Electronic Projects Design/Ideas

    Posted

    Well I talked to the guy that made the DDR circuit and got this response:


    Yeah the MOSFET can sustain 55A in certain conditions of temperature/heat disipation and continuous signal, but i wouldn't get that close to the limit in this application. Anyway, it's current handling capabilities are exceeeding by a large margin the necessary in this situation, and you should be more concerned by the limitations imposed by the wires and connectors (and even the PSU's 5V rail) rather than the transistor.
    Referring to the idea you've proposed, first of all you'll need two power transistors, one for sourcing and one for sinking, with separate buffer circuits for each. The other problem is that a Darlington setup means a base-emitter voltage drop of at least 1.2V, wich is simply unacceptable cosidering your output voltage must have a minimum of 1.25V. You must use MOSFET transistors wich don't have such limitations, but a problem with the control circuit appears, as these need a high gate voltage to completely open.


    I was thinking I could just make a whole new circuit that was adjusted by a pot so I can run it at any voltage I want. Then I dont have to go exactly half, maybe even run it a bit more than half...

    Thanks!

  10. 5v to 1.25-2v

    in Electronic Projects Design/Ideas

    Posted


    Hi Jordan,

    Why do you call the attached design “switching”?



    I thought it was becuase of the switching mosfet  ???

    Told you Im a noob lol.

    Now that you mention that, your right, its definatly linear. The guy said the mosfet gets very hot, and there arent any op amps. Do you think thats a good circuit for like 15amps of clean, stable power? Or, should I add a couple more caps and an inductor?

  11. 5v to 1.25-2v

    in Electronic Projects Design/Ideas

    Posted

    I need a linear 5amp design that has ULTRA clean and stable power that is highly adjustable from 1.25-2v. I need the least droopage possible.

    Ive got a design for 5v to 2.5-4.1v now. Its a switching design. I also need this 1.25-2v design though.

    If someone could help me that woudl be SUPERB!

    Ive attached a schematic of the switching design and the parts are quoted below. If you all see a mistake or see somewhere that needs improving, please tell me.

    Thanks!!!
    -Jordan

    T = STP55NF03L
    IC = TL431
    C1, C3 = 3300uF/6.3V low-ESR
    C2 = 100-470uF/16V low-ESR
    R1 = 390ohm
    R2 = 1.5Kohm
    P = 1Kohm multiturn

    post-9686-14279142446684_thumb.jpg

  12. Capacitor Size Matter?

    in Theory articles

    Posted


    A larger new capacitor has a better ripple-current rating.
    If the capacitor is used as the rectifier filter in a high current power supply, It will have a high ripple voltage across it because its charging and discharging currents are high. A small capacitor will overheat and fail. You might need to use a large capacitor with a higher voltage rating to find one with a high ripple-current rating.
    Large old capacitors have about the same ripple-current ratings as small new ones, so don't just select a larger size.


    cool, thanks. Ive read that its not a real good idea in most cases to go over 150% original capacitance. The voltage doesn seem to matter either. Like I can use a 25v cap in place of a 10v cap without problems. Also Ive read that the low-ESR caps are the ones rated for 105c (usually).

    Sound all up to par?

  15. Buying an O-Scope. Need help.

    in Microelectronics

    Posted

    I want to buy an o-scope. I see ebay is probly my best bet since I dont wanna break myself on a o-scope I'll only use a few times.

    If someone could help me out that would be great. Just need something that works, DC, and is under like $150. I dont want some old peice of crap either.

    Thanks,
    -Jordan

  16. Need help building off this schematic.

    in Electronic Projects Design/Ideas

    Posted

    What about something like this? I know it doesn have VTT, but I think that would be easy to impliment...



    T = STP55NF03L
    IC = TL431
    C1, C3 = 3300uF/6.3V low-ESR
    C2 = 100-470uF/16V low-ESR
    R1 = 390ohm
    R2 = 1.5Kohm
    P = 1Kohm multiturn

    Try to get high-quality parts, so the voltage stays as clean and stable as
    possible. The mosfet (T) gets very hot, so you need to mount it on a
    heatspreader; watch the isolation, it's metallic part of the case is
    connected to the D pin and therefore directly to the PSU's +5V line. The
    output wire should be as thick as possible, because that's the only thing
    it can cause voltage drop. If well built, this circuit should provide zero
    voltage drop and extremely clean power.

  18. Need help building off this schematic.

    in Electronic Projects Design/Ideas

    Posted

    Ive got another guy giving some input now.

    I dont like linear, maybe just me  ;D Switching with good filtering would be the way to go in my opinion...

    What about using the PWM from a PIC to implement a full single phase PWM?

    Feed a N-channel enhancement mode MOSFET as the upper FET with an invertor feeding the lower N ench FET. Feedback referenced against a LM336, output fed through a potential divider to scale it the the ref diode range before going into a ADC channel to compentsate PWM duty cycle to desired voltage. Ouput to basic LC...

    You could also have LCD voltage display (or even temp. with a LM335?), RS232 communication, whatever. The whole thing in one package with a minimal amount of extra components...

    Ive got a shed load of LM336's, low ESR caps, ceramics, inductors, N-channel ench MOSFETS rated from 10A - 48A. I've been planning to build one of these for a while, im planning on using a 16F877, but you have 2 PWM and 8 ADC -why not do Vtt too?

    Only problem i can think of is the ADC being 10-bit, resoloution of 4 mV. Nasty thoughts of it going unstable...

    Maybe just use one of the buck regulator IC's instead and add extra control?


    We have decided to implement a vTT circuit too. That is just another output that will be exactly half of the vDDR voltage. So, if the main voltage was 3.0v, the vTT would need to be exactly 1.5v. I've found out that I will need 3amps on the vTT circuit, but I say call it 5amps to be safe and future proof.

    Now, all we need is a schematic of this idea ^^^^^^^^

    Thats where I ask for help from the pros, here  ;D

    THANKS!!!

    -Jordan

  19. Need help building off this schematic.

    in Electronic Projects Design/Ideas

    Posted

    okay definatly not the second schematic...

    the guy that wrote the first one told me:


    If you can wait until next week, I'll have a go at drawing up a switched mode design, but its likely to be a lot more complicated than a linear supply (at a rough estimate I think I can probably do it with 4 opamps and a few resistors and capacitors and a MOSFET/transistor, unless you can find a dedicated chip to do it all for you)
    IMO, a switching supply will be a bit overkill for the purpose. A simple linear regulator should provide similar performance, but with more heat output.


    this circuit will be used not to power a cpu (close) but to power DDR Memory.

    Ultimately what I want is this:
    http://xtremesystems.org/forums/showthread.php?t=42220

    but they guy wount give me a schematic :(

    sooo, could someone help me with a switching design with lots of caps and chokes to keep the power nice and stable, clean, and cool?

    thanks guys!

    Ive been learning a lot already, been reading and reading and reading on the site. very informative! I already printed out a 50 page pdf book from here too! keep up the good work site admins!

    -Jordan

  20. Need help building off this schematic.

    in Electronic Projects Design/Ideas

    Posted


    Hi

    If you want a clean supply, it is probably a good idea to avoid switching regulators, despite the amount of heath the circuit will generate.
    Capacitors are OK for improving the noise performance, but chokes risk destabilising the circuit; I'd avoid them.
    An improvement to your circuit would be the addition of a ~1K resistor in series with the the gate of the mosfet; although not strictly necessary, it will help in reducing potential parasitic oscillations.

    Lou


    could you possibly show me where and how to add it?

    I have another design that I could use, would this be better maybe?

    http://www.xtremesystems.org/forums/attachment.php?attachmentid=31748

    -Jordan

  21. Need help building off this schematic.

    in Electronic Projects Design/Ideas

    Posted

    I am sorta a noob at this stuff so I need a bit of assistance. I do know how to solder and stuff so thats not the problem.

    What I am building is a power circuit that will convert 12v and 5v to 2.5v-4.3v variable with .01v fluct or less. I will be needing around 15amps, and this schematic is supposed to be enough.

    Ive need as clean and stable power as possible for this project, and I've been told "design seems OK if you follow it..........Also ADD some electrolytic caps to the input and the output of that circuit plus chokes.........." If someone could help me inplement that stuff in that would be GREAT!

    I just need to know what I need to get (parts not tools) and where to get them. I usually get my stuff from Jameco.com

    Here is the scematic:



    Thanks for all the help in advance!!!
    -Jordan

  24. Building a ddr booster

    in Electronic Projects Design/Ideas

    Posted

    is there anyone that would have the knowledge to help me build a ddr booster?

    what im looking for is Xtreme Clean power, and something that can adjust and display the voltage in thousandths.

    i dont need vtt tracking or any of that stuff just a something basic to supply stable and clean power to my ram. i can solder it to the boards vdimm mosfet if possible to eliminate needing a pcd card in a memory slot.

    if this all works nicely im considering making one for the vcore

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