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Posts posted by Um...Me123

  1. I'm new to SMPs but see that is definitely my way to go.  For benefit of learning, what would be wrong with just PWMing a mosfet and putting a cap across the output?  I can see that there could be fluctuations in output when the input changes but besides that is there any reason one couldn't do such a thing?

  2. I know this is getting a little off topic but while I have you all here...
    An led I'm considering is the Luminus Devices CST-90.  It seems to be the best balance between $s and lumens.  $45@2700lm with a perk of having a thermistor.
    Question:  It runs at 3.2-3.7V @ 1-13A
    With a car as the source what is the best method of power supply which has the following qualities:  cheap, easy, full dimming, and doesn't destroy led in 2 days?

  3. Some very good things to think about on the last posts.  Thanks   My reasoning for the peltier is because I don't think a fan would be reliable enough because of dust/rain and I know peltier use a ton of power but I don't see too much of a problem there as long as the car is running, right?  Some of the leds have a thermistor built right in so that would help and I could PWM the peltiers accordingly to save power as well.   I just have no general idea of how big the heat sink needs to be so my vision is that heat sink only is out of the question.  The fogs are mounted in what would be better called the bumper cover so there isn't much to work with except plastic but it's been a few months since I had it apart.

    Found something very helpful: "http://www.luminus.com/stuff/contentmgr/files/0/0179ad38a075ca3c31f708ed19392fa3/miscdocs/960031_rev_a_dk_414n_and_dk314n_development_kit_manual.pdf
    User manual for the dev kit for the RGBW led...it can approach 120W!!!  $850 though :(
    Sink = 82 mm x 65 mm x 38mm plus fan

  4. I did notice that Phlatlight had a RGBW (perfect for my app) that is brighter than the 40W but its $200.  yaouch

    My idea is to use these on my car as fog lights.  Already have regular halogen ones so it would replace the bulb only, using the stock reflector.  I would be able to precisely color match my HIDs and have a bazillion other options to fit whatever situation.  My only worry is cooling.  The brightest led I've worked with is a 1watt so I'm not sure how to approach it.  All application notes have all these equations and junk but I need to see practical examples.   My space and availability to mount and secure a giant heat sink is limited so I was thinking of using a peltier and maybe a small fan on the hot sink but I have zero experience with those as well.  Tinkering is out of the question because of part cost so planning is vital.  Has anyone ever worked with these super leds?  If anyone knows of links to projects (videos/pictures/instructs) using 15+ watt leds that shows the cooling process that would be great.  
    I'm still in the "is this possible?" stage of this one.

  5. Im really dumb and all so maybe I can provided some simpler input that's more than likely useless.  The experienced guys confuse me a lot.  Use a LED maybe?  If it needs to be hooked to a comp then use a relay and have a high pin connect to a low pin through the switch.  What ever your interface is, I dont know but theres a program called ParPort that will allow you to tun on pins and detect a high signal on the inputs.

    Be as cautious as possible when hooking stuff to a comp.  When I was a little younger I hooked a phone line directly to my headphone jack (bad idea).  50V + soundcard = boom!

  6. Any ideas on what methods to use to check various lengths (max of at least 100') of audio cable for things that may cause line noise or cutting in and out?  I have some ideas but need help.

    What specifically causes line noise?

    Another question I have that may play a part in this is how do devices detect different things using different voltages...Um how does a panel of buttons work that only have two wires going to it (with diff resistors).  (How does the receiving end differentiate between the voltages??)  Do transistor have a "cutoff point" or something or how does this work?

    Thanks for your help.

    Edit--- comparators--is that the thing in my last question?  What are they?  Also use for progress bar type thing.

  7. I went back to re-challenge these IR deals with a project that would make lights go on when you enter a room and off when you exit.  The IR leds can communicate now but for only about 4-5 inches at a 1ms on / 5ms off pulse.  (in low light conditions)  I'm just learning but I want to know how to make the IR beam work at a farther length (across a doorway)  without increasing the off time.  I have 5V from the PIC board or could get 9V from the PS (then using a transistor) if that helps.
    Looking through a video camera these IR leds seem to be significantly dimmer than a remote control.  How do they make them work so far away?

  8. I bought some infrared leds and phototransistors on ebay.  Hooked them up to a microcontroller board and  put them right face to face and no sound.  I looked with a video camera and the infrared was blinking.  Tried with a sterio remote and it did beep.  I know the emmiter can do 940nm and I really don't understand this.  If the phototransistor can only do a lower ammount 800 something? will it not work?  Can I lower the wavelength of the emmitter somehow if this is the case?  I just need help in understanding infrared.  I checked the code and am pretty sure the "IF IN15 = 1" part isn't just during the off stages of the LED.

  9. OK So I bought this LCD panel meter to measure VDC (20Max) and I hooked a 9V battery to the power leads and it said 0.00.  Great so I hook it up again 5 minutes later it didn't work and has never worked again.  Bought another one finally several months later (has to be ordered) and I just hooked it up (said 0.00) and I hooked it up again (after going up the stairs) when I was about to put it into the panel to make sure I new the polarity and it didn't work!!!!!!! I can't get it to work at all now!!!!  What is going on!!!!  I'm really mad at this point because it's not cheap.

  10. Just Installed a car alarm for my friend and saw that the basic way in which is works is very simple.  I want to build a simple system for my own car, which happens to be wayyyyyyy more prone to a break in than his anyway, using some shock sensors and possibly door detection (using dome light wiring and a hood pin)  Has engine imobilizer (sp?) so I don't know if it's worth the trouble.  I just don't want kids at school to be messin around with my car.

    Below is where I'm at in my basic concept of transistors.  Please let me know if in the instance either button is pushed the light (marked alarm) will illuminate.

    The program gave me an error with the PNP and I just attempted to grasp their concept today so I don't know.

    Thanks all!


  11. OK-------Back to the car thing...
    I got my lighted switches yesterday and just installed into the dash (was a little scary to think my new car could have a big hole in it if the switch didn't fit.

    The switch is a NKK pushbutton (on-off) that SPDT with isolated led leads/pins whatever you call 'em.

    The fog light button is in the same panel I removed and I tested the wires


  12. Working on another project dealing with the electricity choosing the path of less resistance thing.
    In the circuit a car deck has an auto antenna wire that goes 12V pos when the deck is turn on.  This in turn connects to a spot on the amp that signals it to turn on.  I have a (LED) lighted DPDT that I want to use to switch it.  Conditions for the switch being lighted are when the deck is on (because the supply is from the amp signal wire) and when the switch is on.  Here's the circuit but once its all wired up will the LED even light?
    Thanks-fast responce would be very helpful.


  13. The LED is an unknown sourse of light

    maybe its a led
    maybe its some sort of electroluminence (sp?)

    I just threw in an led to show that (resistor is there then)

    Yes I forgot the reverse diode.

    You always need a resistor on the base side of a transistor?

    Another question:
    in the case of the transistor or a led and the supply voltage is equal to the spec. voltage what sort of resistor so you use?  1 ohm?

  14. Um...you may have a good point in the first 3 lines.

    I always get stuck on the idea that electricity chooses it's path...sort of.
    Like say you have a 12V supply and you hook the leds and buzzer and the led is 3V and buzzer is 12V- You obviousely have a resistor for the led (in the assembly) so the electricity will go almost completely through the buzzer because it's "the path of less resistance".  This always hangs me up and if there is a short way to explain it feel free but if its long and complicated don't waste your time.  I'll either spend a looonnnnggggg time sifting through all the articles out there for one simple enough for me or just wait untill my properties of electricity class.  Again, I don't want to waiste your time if its a long explanaition.  My question was pretty much answered in your first 3 lines.  If that for some reason doesn't work then I'll post a schematic.

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