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  1. AnalogKid

    Voltage Follower Doesn't Work

    As AG said, the *circuit* for most amplifiers has a ground. That is not the same as an individual component like an opamp having an explicit ground *pin*. Most don't. However, some opamp circuits have one of the inputs connected directly to the circuit ground node. Note that while one of the...
  2. AnalogKid

    NPN circuit isn't switching after power change

    When battery-powered, the ground references for the sensor and the keyboard are different. What is the sensor? manufacturer? Data sheet? What are the two rectangles within the USB rectangle? ak
  3. AnalogKid

    Problems with composite video generation!

    The 4040 is a ripple counter. There can be a significant delay between the time of a clock edge and the time when all outputs are stable. Of course, this is worse when two 4040's are cascaded. ak
  4. AnalogKid

    Build a 120 vac to 18vdc Power Supply for DC Tool

    A 360 W linear power supply probably is what you were thinking about when you asked. It would need a 500 W power transformer. Think 5 pounds of iron and copper, larger than a softball. After that it is big diodes and big capacitors. The circuit is relatively simple, but the scale of the...
  5. AnalogKid

    Modifying AGC circuit

    That was ADI's way of competing with dbx, SSM (acquired by ADI and copied by Burr-Brown), and THAT. THAT makes the gold standard parts. ak
  6. AnalogKid

    Modifying AGC circuit

    Chris - One of my favorite surface mount caps is a 10 uF 50 V XR7 ceramic in a 1206 package. That little puppy could decouple *anything*. Now you get all of that in an 0805 or smaller, but 15 years ago it saved ma a lot of grief. We also used big flat 400 volt SMT ceramics in a MIL power...
  7. AnalogKid

    Problems with composite video generation!

    That is not a TTL, CMOS, or ECL logic part number. Is the counter referred to pin post #1 a physical part or is it implemented in firmware? ak
  8. AnalogKid

    Problems with composite video generation!

    The data sheets are correct. What is the counter part number? ak
  9. AnalogKid

    Modifying AGC circuit

    Ceramics will work fine. But for the average hobbyist, a 10 uF ceramic is much more expensive than an equivalent aluminum electrolytic. This circuit has fast attack and slow release. That is, it responds very rapidly when the signal is too high, but takes much longer to turn up the signal if...
  10. AnalogKid

    Modifying AGC circuit

    A classic old circuit from the wayback machine. If you really want to build something from scratch, this will work. FYI, adafruit, ebay, et al have low cost AGC modules. Some are based on a single-chip AGC part made by Maxim. 1. A transformer will work, but you don't need one. Each of the...
  11. AnalogKid

    Voltage Follower Doesn't Work

    Start with the data sheet. It will tell you the max and min power supply voltage range. The minimum is more than 1.5 V, so that is a lot of your problem right there. Separate from that is the fact that powering an opamp is a bit more complex than you think. Most "normal" opamps expect to see...
  12. AnalogKid

    What is the name of this mechanism?

    Packetizer, Ser-Des (serializer-deserializer), lotsa recently-developed names. But the original name is a multiplexer. Originally developed to push multiple independent telephone conversations down a single pair of wires, you can use either analog or digital signal techniques. For simple...
  13. AnalogKid

    LED timer circuit

    There is a CMOS counter chip called a CD4060 that will do this with minimal parts and no programming. However, it will not have great accuracy. The problem is that electronic circuits can time seconds, milliseconds, and microseconds with outstanding accuracy. But for longer time periods (24...
  14. AnalogKid

    I am looking if anyone can help me make a timer circuit with an input and output switch

    If you already have the timer module/device/whatever, please tell us what it is, or post a link to where you bought it, or post a photo. Two LED / photo transistor light beam detectors can capture a falling object, but there are a zillion different timers in the world. ak
  15. AnalogKid

    What the latch?

    The 7414 is not a flipflop, it is a hex inverter, and is available in a ton of different technologies (LS, HC, AC (my fav), etc.) ak
  16. AnalogKid

    Novice project, help needed

    From your question, it sounds like you don't have the experience needed to build *safely* a mains-powered power supply from scratch. So I recommend getting a generic USB charger/adapter with a 5 V output. Once you have a safe source of low voltage power, there are lots of things you can do...
  17. AnalogKid

    New to electronics, have a basic build

    If your weighing platform has only one load cell, then the uC needs only one A/D input if it has an internal reference. That narrows the field to just under i gazillion parts. The real question is what are your programming skills? ak
  18. AnalogKid

    Need audio preamp/buffer constant current (power) for bussing

    The basic concept of a virtual ground summing amplifier has been around since the 30's. Here are a few variations on the theme...
  19. AnalogKid

    Need audio preamp/buffer constant current (power) for bussing

    Yes, please post some of the schemes, at least so we don't suggest something you've already tried. There are several ways to create a summing buss, some (like constant current drivers) more complex than others. With the most simple, as each note is added the output volume increases...
  20. AnalogKid

    What the latch?

    Re-reading post #5, yes - the master reset button needs an isolation diode. Nice catch. ak
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