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  1. AnalogKid

    Bench Power Supply

    Post #41, Figure 26 - look at the bridge. ak
  2. AnalogKid

    Help to solve Operational amplifier

    In post #4 you said to assume the opamp was ideal. What are the characteristics of an ideal opamp?
  3. AnalogKid

    Help to solve Operational amplifier

    No. What is the maximum output before distortion?
  4. AnalogKid

    Help to solve Operational amplifier

    Task 2: The output voltage equals the input voltage times the gain of the amplifier circuit. Since you know the maximum output before distortion, you can divide that value by the gain of the amplifier to find the equivalent input voltage. ak
  5. AnalogKid

    Help to solve Operational amplifier

    Easier for me, but what about you? What work have you done to answer these questions? You used the term "ideal" to describe the opamp as a way to qualify the questions, so you must know what it means What are the essential characteristics of an ideal opamp, and how do they apply to your...
  6. AnalogKid

    Help with a simple receiver.

    There is nothing wrong with the 4.7 uF capacitor. Leave it in the circuit as shown. I have not seen this approach to an AM receiver before. Here is my first-pass opinion of its operation. The transistor is acting as a half-wave rectifier with gain. To overcome the relatively large forward...
  7. AnalogKid

    Type of wires

    Shielding a wire helps prevent the signal being corrupted by radiated interference. For RS-232, usually the cables are not shielded. When they are, eash wire is not shielded separately like audio or video cables. Instead, it is a single shield around the group of individual wires...
  8. AnalogKid

    LM3914 LED dot display

    It might work in dot mode, but it will not work in bar mode. The outputs are not simple open collector transistors, they are controlled current sinks. That is why I recommend an isolation diode for each output being combined. ak
  9. AnalogKid

    Stability of voltage regulators

    The vast majority of electronic components way outlast their ratings, life cycles, and other datasheet data. That's why a TV lasts 10 years when everything inside is rated for 1 year or less. And an amateur is free to run at the edge of the envelope with no serious consequences. But for a...
  10. AnalogKid

    LM3914 LED dot display

    With 10 diodes to a single LED. ak
  11. AnalogKid

    Simple LC Oscillator

    Not true, of course. The opamp output is a low impedance voltage source designed to provide a signal output to some other circuit or use. Connecting between the opamp output pin and the circuit ground is the best way to observe the oscillator output signal. Another way is to connect a high...
  12. AnalogKid

    Type of wires

    From two websites: The specification recommends 24AWG twisted pair cable with a shunt capacitance of 16 pF per foot and 100 ohm characteristic impedance. The standard also states that the maximum cable length is 50 feet, OR the cable length equal to a capacitance of 2500 pF. The latter rule...
  13. AnalogKid

    ultrasonic sensor at 40 KHz

    What is a GUIDE? Is this a homework problem? That is a gain-bandwidth of 3 million. That's a lot. The TL081 datasheet says this is the max value for the part, so it would be operating open loop (not god). You will get better results with a compound amplifier, basically two amps in series...
  14. AnalogKid

    Simple LC Oscillator

    As shown on the 9th image on the page you linked, the output comes from the output of the opamp. ak
  15. AnalogKid

    RFID Tag Detector

    12 inches is an enormous distance for an RFID tag. While shoplifting tags can be detected at this distance, they work on a different principle. Separate from that, I think you need to read up on how passive RFID works. It is a broadcast-powered electric field modifier, and since anything...
  16. AnalogKid

    The Day The Symbol Changed

    Raised on 60's Popular Electronics, Zenith TV, and Ampex and RCA broadcast equipment schematics, now do MIL electronics. What we use from post #1: Chassis Ground symbol = both chassis and earth ground, since they are the same in MIL systems. Earth Ground symbol = system ground, signal ground...
  17. AnalogKid

    a couple of composite video questions

    It should. The layout techniques that create a constant impedance signal path are stripline and micro-stripline. ak
  18. AnalogKid

    Boost converter with no controller

    Without feedback, *no* power converter - buck, boost, switching, linear, whatever - can maintain a constant output. All converters rely on feedback of some kind for regulation. Also for all converters, the maximum outut voltage, current, or power is determined by the power available from the...
  19. AnalogKid

    Please help me with a simple circuit

    One LED directly across the battery to show that it is installed. One LED after the safety (key) switch to show the controller is hot. One LED after an output switch to show that the output is live. Correct? ak
  20. AnalogKid

    DC-DC Buck Converter

    Don't know about burning up, but it might shut down due to an overcurrent. To answer your question, when multiple loads are connected in parallel their load currents sum, or add up. So three 2-amp loads need a 6-amp source. Depending on the nature of the loads, they might draw 2 A...
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