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  1. AnalogKid

    High Efficiency USB Car Charger

    The 34063 is the darling of the car charger universe and is in every one I've taken apart, one port, two ports, whatever. If you don't need the packaging, most car chargers open up by unscrewing the collar around the sprint-tip. ak
  2. AnalogKid

    Current Limiting Inputs Into Microcontroller

    Yes, you need the LED current limiting resistors no matter how they are driven. But you don't need base current resistors for the 2003 (as opposed to individual driver transistors), and you can easily run 50 mA or more per LED if you want. Even if the micro is rated to handle 5 mA per output...
  3. AnalogKid

    Energy Monitoring (Formulas and methods help)

    For a buck fifty that's disgusting. I notice the datasheet has 0.0 interface guidance. BTW, Analog Devices also is big in power meter ICs. ak
  4. AnalogKid

    Energy Monitoring (Formulas and methods help)

    For AC voltage and current monitoring you have two options, not counting the manual way with a zillion readings and a ton of calcultions. One, if you are sure the waveforms are all going to be sine waves, use a rectifier and filter to get a DC voltage that is related to the sinewave peak...
  5. AnalogKid

    Can any body help me in making dual 24 Volt 5 amp Regulator??

    Attached is the LM7824 datasheet. Page 20 figure 13 has a high current booster ircuit that will do what you want. Figure 14 is the same circuit with added short circuit protection. Also attached is an expanded circuit for much higher output currents. All of these will work with the 7924 and...
  6. AnalogKid

    Pulse transformer

    Colin. I was responding to his post. I should have trimmed more. ak
  7. AnalogKid

    Pulse transformer

    I've been reading your posts for a while now, often wondering the same thing. Your command of semiconductor history is very interesting. How old are you? ak
  8. AnalogKid

    Electronics Project Help!

    Yeah, about that inverter - using a circuit to turn low voltage DC into true sinewave power so that another circuit can turn it back into low voltage DC to run the amplifier electronics seems just a tad inefficient. OK, make that very inefficient. If the TS wants to build something, open up...
  9. AnalogKid

    Can any body help me in making dual 24 Volt 5 amp Regulator??

    I agree with Dave. The circuit using a PNP power transistor to boost the output current of a fixed output positive voltage regulator is decades old and very well understood. If yours did not work, that is the place to start. Please post a schematic that includes the power transformer...
  10. AnalogKid

    Electronic supply, help.

    That's exactly my point. Correction: $3.42, not $2.00: http://www.ebay.com/itm/USB-White-Emergency-Portable-2-AA-Battery-Power-Charger-for-Android-Cell-Phone-/301194676175?pt=LH_DefaultDomain_0&hash=item46209a07cf ak
  11. AnalogKid

    Electronic supply, help.

    I think Colin is actually Kanye West. ak
  12. AnalogKid

    Electronic supply, help.

    There is no manufacturing process available in the US that can produce battery chargers competitive with offshore products. I can buy a single unit for $2, packaged for sale and including international safety agency approvals. Your bare pc board will cost more than that in hundreds. Like chop...
  13. AnalogKid

    Electronics Project Help!

    Adding on - nothing will get you longer battery life than an amplifier designed from the ground up to be battery powered. I don't know if you know the differences between traditional, linear audio amps and newer, switching (Class D) amps, but there are many and this application is why. I know...
  14. AnalogKid

    How to best simply invert a 110v ac current w/minimum change to the voltage

    For noise already on your input powerline signal, invert and add will cancel the noise voltage as well as the power line voltage. Balanced noise suppression techniques work only when the noise is added *after* the balanced signals are created. To measure the noise on a single powerline phase...
  15. AnalogKid

    How to best simply invert a 110v ac current w/minimum change to the voltage

    I also have no clue what he is trying to do, but I understand the question. Yes. If you do a very good job of inverting a non-DC signal, you can sum the two signals to get zero, the definition of perfect invert-and-add. In the real world there is no such thing as *perfect* inversion, but in...
  16. AnalogKid

    cheap mains stepdown 240-120

    The above ideas work only for items with linear power supplies. OTOH, items with switching power supplies probably have universal inputs, but you won't know unless you check. ak
  17. AnalogKid

    How to best simply invert a 110v ac current w/minimum change to the voltage

    This might be a simple as one small transformer, but your question doesn't have nearly enough information to work with. "simply inverted" is not a good description of anything. Traditionally, an inverter is a DC-input, AC-output power supply, and there is nothing simple about them. Please...
  18. AnalogKid

    Power supply return path question

    Your generalizations of the characteristics of return paths vs. frequency are too broad. Yes, inductive reactance increases with frequency, but it always is a performance factor. Also, area and thickness are factors that contribute to the effectiveness of a return path design as much as...
  19. AnalogKid

    Wireless charging and audio playback from cellphone?

    The Boost is an inductive receiver, not a transmitter. Very different circuits, very different inductor designs. You can't push audio backwards through an amplifier. ak
  20. AnalogKid

    Electric Calculations

    LED's are current-mode devices. Putting two diodes in series with a 5 V output will not provide any current limiting, and could damage the LEDs. The best way to size a series resistor is to determine what current you want through the LED, look up the corresponding forward voltage on the...
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