Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. geekEE

    How the heck do you solder SMD's that have pads underneath?

    Try adding a bunch of liquid flux and reheating until the solder reflows. That stuff works wonders
  2. geekEE

    Exponential linear equations

    Unfortunately it seems like the Lambert W function is not something for which you can easily solve. The Wikipedia page shows that it's only defined as an inverse relation. I think you're still going to need to solve this numerically.
  3. geekEE

    switch off motor with limit switches

    Unfortunately I don't have such direct control over the motor. It's already installed, and it's a closed system where I can only send serial commands to it to tell it the direction and speed. I just want to add a fail-safe way to kill power in case of computer bugs, crashes, etc. I'll have to...
  4. geekEE

    switch off motor with limit switches

    Hi all, I have a low-speed motorized turntable that I would like to modify by adding a couple of limit switches (maybe reed switches?) that will kill power (120VAC) to the turntable if it hits either switch. Additionally, I would like to have a push button that will let me override the system...
  5. geekEE

    Audio through a transformer.

    I don't think a power transformer, meant to handle 50/60Hz would be a good choice for telephone audio, which can be almost two orders of magnitude higher in frequency. Also, I would suspect that a power transformer doesn't need to be shielded for noise the way that a good audio transformer would...
  6. geekEE

    What is a "Humming Window" (Digital Image or Speach Processing ?)

    Sounds like they meant Hamming Window
  7. geekEE

    Creating block diagrams for systems

    It looks like you are considering low-cost or no-cost block diagram solutions, so I might suggest the open-source program LibreOffice Draw or maybe Dia. Glenn
  8. geekEE

    sine wave dimmers

    Are there any sine-wave dimmers that will be a replacement for those noisy triac-based dimmers? The load consists of incandescent lamps of maybe 1500-2000W (120VAC 60Hz). I would like to eliminate some electrical and audible noise for an audio listening room. I suppose I could use variable...
  9. geekEE

    Which DMM can you recommend?

    I have used BK Precision for a good meter with a lower price than a Fluke.
  10. geekEE

    voltage modification

    Glad to hear you got it working. I had a couple comments though. First of all, make sure that the rated temperature range of your op amp is not exceeded. If you have this circuit under the hood, the temperatures can be very high. Secondly, you said that your supply rails are +6V and -6V. How...
  11. geekEE

    High-side PMOSFET failing (can't turn it off after a few days)

    Do the large capacitors have to be on the drain of the MOSFET? Couldn't you put them on the source of MOSFET instead? You can put some smaller, faster caps on the drain. Glenn
  12. geekEE

    Looking for ideas on electronically switching resistors.

    When you say a "specific operating point," do you mean a particular current? i.e. is the voltage fixed? If so, then how about a current source (or sink) circuit with feedback to set a specific current? Glenn
  13. geekEE

    Secondary batteries with wider temperature range?

    Wow, Saft has a Lithium cell that charges at a temperature of 125C? That sounds terrifying! I'll check them out. Thanks! Apparently my Google-Fu is weak.
  14. geekEE

    Secondary batteries with wider temperature range?

    I've been looking at small (something like 18650 size) lithium-ion batteries for a portable application. However, these batteries typically don't want to be charged above a temperature of 45C or discharged above 60C. Does anyone know of a source of other types of batteries that can safely...
  15. geekEE

    Lithium Polymer Batteries

    That battery is designed to be charged to 4.2V for the rated capacity, so you will have a lower capacity at 4.1V, but it will only be slightly less, depending on your discharge rate. Take a look at the graph on this page. http://learn.adafruit.com/li-ion-and-lipoly-batteries/voltages Glenn
  16. geekEE

    0.2-2uF cap with lowest ESR, concrete ESR values?

    If you're using ceramic caps in an audio circuit, watch out for microphonic effects. I've built amps that ended up amplifying the sound of me tapping on the PCB with a screwdriver. This effect is much worse if the source of your audio is a relatively high impedance. If size is not important...
  17. geekEE

    need regulator circuit that is efficient at both low and high currents

    Update: I found that Linear Technology has PowerPath controllers that will work like dual ideal diodes. Glenn
  18. geekEE

    need regulator circuit that is efficient at both low and high currents

    VE1BLL, unfortunately I'm using a CPU module that doesn't allow me to separate the low-current and high-current circuits. IRstuff, that chip seems to change the behavior of the switching reg by putting it into a "burst" mode, but it still uses milliamps of quiescent current. I think there are...
  19. geekEE

    need regulator circuit that is efficient at both low and high currents

    I'm designing a battery-operated device that needs a 5V supply that draws microamps when asleep, but about 2Amps when it's awake. If I use a switching regulator, it will be much more efficient when awake, but the current draw when asleep will be higher. If I use a linear regulator, it will be...
  20. geekEE

    Determine Vout

    Maybe I'm being picky, but you can't get four significant digits on the answer when the resistors all have one significant digit. Glenn

Part and Inventory Search

Back
Top