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  1. hevans1944

    Including header files

    Perhaps the operating manual for the compiler might offer a clue. Or check out this page of Frequently Asked Questions. And microchip has a nice forum where you can find answers to questions like yours. I'm sorry, I don't do much C (or pay money for compilers), but maybe @chopnhack will see...
  2. hevans1944

    Voltage sensor 10-15v

    From close inspection of the traces on this "product" it appears to be nothing more than two resistors connected as a 1:5 voltage divider. There does not appear to be any active components, so the +Vcc connection doesn't serve any purpose. Buy a screw-terminal 2-wire connector, a three-pin...
  3. hevans1944

    Sony reel to reel tape recorder inquiry

    This guy is an end-user and probably not well-versed in electronics. The two outputs are labeled "speaker" and "monitor" not "connect your CD recorder here" or something similarly useful. When this tape deck was popular I don't think CDs had been invented yet. Many folks who ask questions here...
  4. hevans1944

    Loss of voltage with MOSFET

    Measure the voltage drop from drain to source at the MOSFET to make sure it isn't part of the problem. When you are ready, MOSFET H-bridges are more efficient than BJTs, and there are integrated circuits available to drive them, including high-side charge pumps for the top legs of the H-bridge...
  5. hevans1944

    Power Resistors Value

    Yeah, I think I saw Chewbacca using one of those after showering, shortly after escaping from the Death Star in the Millennium Falcon.
  6. hevans1944

    Ultrasonic Metronome, or rangefinder transmitter

    You could try this one. Inexpensive and waterproof. I would purchase two of them, one for generating ultrasonic pulses and the other to receive them. Then use a variable-frequency oscillator to find the resonant frequency of the transmitting transducer by sweeping the frequency near 40 kHz and...
  7. hevans1944

    Sony reel to reel tape recorder inquiry

    Well, it was free... and SPAM is easy to delete if that happens.
  8. hevans1944

    Sony reel to reel tape recorder inquiry

    Look closer. There is a speaker jack and a monitor jack located on the left side of the recorder. Also see page 15 of the Owner's Manual.
  9. hevans1944

    Power Resistors Value

    They probably would make decent boat anchors too. Negative buoyancy probably.:D
  10. hevans1944

    Help! Arduino based car not working when touching ground.

    It sounds like your motor shield is not providing enough current to the motor when the car is on the ground. Are you using pulse-width modulation (PWM) to control the motor? That may be the source of the sound you hear as the motor stalls when you place the car on the ground. A circuit diagram...
  11. hevans1944

    Ultrasonic Metronome, or rangefinder transmitter

    Some Polaroid cameras had ultrasonic range finders that were used to adjust the camera focus for nearby objects. If you can find one on Ebay it could be a useful reverse-engineering experience. Radio Shack sells ultrasonic range finders, and they are also available on Amazon, but distance is...
  12. hevans1944

    Bigger Arcs

    The 50 cm per 500 kV arc distance is only an approximate figure. To arc a distance of one meter (1000 cm) requires about 3.4 MV, so twenty times the distance of 50 cm (1000 cm) requires only slightly less than seven times the voltage to produce an arc in air. An arc, by definition, is a...
  13. hevans1944

    Bigger Arcs

    There is a huge potential difference between the Earth and the upper atmosphere that is responsible for world-wide lightning discharges at a rate of about fifty or sixty strikes per second. The Japanese have been using lasers to encourage these strikes for the purpose of testing the survivabilty...
  14. hevans1944

    Loss of voltage with MOSFET

    Even with the slightly larger Rds(ON) of 0.035 Ω with lower gate drive, we are still only talking 85.7 millivolts drop at 2.5 amperes. I would measure the voltage from drain to source with the MOSFET gated ON to verify it is the culprit here. As @Alec_t suggested the problem could also be in...
  15. hevans1944

    Loss of voltage with MOSFET

    I see no reason for the excessive voltage drop across the MOSFET. This is a "logic level" device according to the datasheet. Try replacing the MOSFET with a new one.
  16. hevans1944

    12v relay with time delay and reverse polarity

    I didn't find it in Circuit Help, but there is a similar discussion from the same poster (@john2k ) in Electronic Projects here on September 11, 2012... more than three years ago! Wiper blades must have worn out by now waiting for a solution.
  17. hevans1944

    12v relay with time delay and reverse polarity

    Hmmm. Maybe, but why the reversing polarity? Wiper motors run in one direction only. The oscillating wiper blades is a mechanical function.
  18. hevans1944

    RF amplification

    The capacitance (a few pico-farads) becomes important at higher frequncies, affecting both slew rate and peak-to-peak amplitude. There are also impedance mis-match considerations at higher frequencies which can cause reflections (standing waves) on the connecting coaxial cables. The biggest...
  19. hevans1944

    Capacitors

    There is no such thing as a "standard capacitor". Ceramic capacitors are useful up to about 0.1 μF capacitance and as low as a few pF. They are available with various temperature coefficients (capacitance versus temperature) that can be important if used in tuned circuits. A ceramic capacitor is...
  20. hevans1944

    Capacitors

    Depends on what you mean by "understand". There is some math associated with describing how capacitors behave. You can rote memorize the formulas and that will probably be enough to get you by, but deeper understanding would come from a good physics course. Here is an excellent web site for...
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