Search results

Search Forums New Posts
  1. AnalogKid

    Please help me to run 4 LED's in series from 12v.

    The problem is the "spec" for the LED. While all LED's have a forward voltage drop, it is not a reliable way to regulate the power in the device. High power LEDs have an optimum operating current. When you drive them with a constant current source at the appropriate value, you will see the...
  2. AnalogKid

    Creating own usb to rs422 cable adapter

    The USB and RS-422 protocols and data formats are completely different. The 4 RS-422 connections are transmit+, transmit-, receive+, and receive-. The 4 USB pins are +5V power, data out, data in, and Ground. You are describing a simple connector adapter, but an RS-422 USB device has a...
  3. AnalogKid

    AV audio video red yellow white application

    Decent video is flat down to 30 Hz. ak
  4. AnalogKid

    Driver circuit

    In post #8 I said that the circuit could be "adapted to a +/- 24V output by changing the zener diode ratings." and included a link to a thread on another forum where I explained its function. I was surprised by your questions in post #11, and said so in post #12. Your response in post #13 was...
  5. AnalogKid

    Driver circuit

    To me, 3,294 posts indicated an awareness of transistors and zener diodes sufficient for this circuit. Sorry for the assumption. An important aspect of any bipolar or totem pole output stage is the management of cross-conduction current, the current that flows through both output devices when...
  6. AnalogKid

    Driver circuit

    I am surprised by your questions, given that the circuit is so simple and is explained in the original thread. Thanks to the brilliance of the capacitor (which those *other* people never quite got), the rest of it is so simple even Colin can do it. ak
  7. AnalogKid

    Driver circuit

    What is the output current? What is the output impedance? What is the output for? Better information = better answers. This is something I did for another thread. It can be adapted to a +/- 24V output by changing the zener diode ratings. Because of the coupling capacitor this circuit...
  8. AnalogKid

    AV audio video red yellow white application

    An analog signal that usually is asymmetrical about ground. The yellow input might have a DC clamp trying to figure out where the back porch is. ak
  9. AnalogKid

    Miniture power supplies ?

    Digi-Key, Mouser, Newark, All electronics, Marlin P. Jones, Surplus Traders, Electronics Goldmine, Electronic Surplus, MCM, Timeline, ebay, amazon. 12 volt charger, 12 volt battery charger, 12 volt supply, etc. ak
  10. AnalogKid

    Unknown Farnell Power Supply Questions

    This is a switching power supply, which means that the power transformer is designed for a specific range of current, frequency, and pulse width values. Changing the output adjust components or manipulating the remote sense input both will work up to a point, but that point is nowhere near a...
  11. AnalogKid

    USB 5V power from 12V car supply

    All true, but an inline fuse would be prudent. ak
  12. AnalogKid

    Inject sound to a phone landline

    Is the source really 0.6 mV (600 uV) or is that a typo? What is the source? What is the output voltage at normal volume levels? What is the current capability? Is it a speaker output from a small amplifier, the line output from a computer, the earphone output from an MP3 player - what? Your...
  13. AnalogKid

    sensor help

    I suggest an energy-harvesting acoustic transducer. Hang a small bell on the end of the pole. ak
  14. AnalogKid

    Inject sound to a phone landline

    Now that we finally have a drawing, we see that the original question was poorly stated, and unintentionally misleading. There are two basic types of telephone handsets, one with a carbon microphone or equivalent, and one with an electret microphone. The more modern the phone, the more likely...
  15. AnalogKid

    How do you not run outta batteries?

    Yes, I did. I also read the first four words of post #1, thought about what I would want to know within the contexts of posts #1 and #4, saw a potential for unexpected and potentially destructive results, and filled in some details missing from all previous posts. I wrote my response...
  16. AnalogKid

    Name that switch!

    Well, maybe one "much" more. After my wife went through one I did some digging and whipped up a couple of flavors. Lotsa gain but not much bandwidth for a generic circuit, and probably "much" less bandwidth for this application. Without seeing his circuit we can only guess, but my guess is...
  17. AnalogKid

    Homemade Capacitor

    Yeah, my fingers got ahead of my brain, twice. As for the amount of film, that was my point. Way too big a requirement to teach anything useful. ak
  18. AnalogKid

    Measuring distance of many targets

    "Maybe is helps to proper explain my scenario?" Yup. Also, why is laser ruled out. A laser rangefinder on a rotating platform is a cheap optical radar. ak
  19. AnalogKid

    Inject sound to a phone landline

    I've used both transformer types. The transistor amplifier output transformer can have better frequency response, but small ones saturate with the telco DC line current. This can be 100 mA or more in some situations; a lot of uncancelled flux. A 600:600 modem transformer is built to handle...
  20. AnalogKid

    Homemade Capacitor

    >1F is an enormous amount of charge, up in the trick question range. There probably is one material that is available and has the right properties, and unless you figure that out you're sunk. This kind of test is more about the superiority of the questioner than teaching. Moving on, cheap...
Top