Search results

Search Forums New Posts
  1. hevans1944

    Combining multiple amplified outputs to feed one speaker only

    Perhaps you could passively sum the four 8 Ω outputs by connecting each to a 27 Ω, 5 W, resistor. Connect the other end of each of the four resistors together to an 8 Ω speaker. The original output signals will each be attenuated by a factor of about 0.12 so the gain of each amplified channel...
  2. hevans1944

    12VDC to 100DC is it possible?

    This is a manifestation of a perpetual motion machine of the first kind. Your scheme purports to take energy from the battery to drive the motor, which in turn drives the alternator to replenish the energy removed from the battery. This scheme will never work because, along the way, some of the...
  3. hevans1944

    Narrowboat (Waste) Holding Tanks - LED level indicator

    The RED and ORANGE LEDs operate independently. When the corresponding switch is OPEN, its LED will be ON. If both switches are OPEN, both the RED and the ORANGE LEDs will be ON.
  4. hevans1944

    12VDC to 100DC is it possible?

    So, the electric motor shaft on one end of the motor is connected to clutch/gear box/wheels? And the electric motor shaft on the other end of the motor is connected directly, or with belt and pulleys, to the alternator? And where is the electrical output of the alternator connected? To the 72...
  5. hevans1944

    Narrowboat (Waste) Holding Tanks - LED level indicator

    It looks like you need to connect the two inputs of the third NAND gate to the outputs of the first and second NAND gates to light the GREEN LED when BOTH switches are CLOSED. As drawn, the GREEN LED lights only when both switches are OPEN.
  6. hevans1944

    12VDC to 100DC is it possible?

    Typical automobile three-phase rectifying alternator can produce way more than 14 volts at normal operating speeds by controlling the field current, but there is no guarantee the diodes won't pop if their peak inverse voltage rating is exceeded. Some folks remove the diodes and just use one or...
  7. hevans1944

    Need help with electronic circuit (Make: Electronics Experiment 8)

    The original design (with a large capacitor across the relay coil) depends on relay coil hysteresis to oscillate. Hysteresis in a relay coil means that the current (or voltage) required for the coil to actuate (move) the contacts is greater than the current (or voltage) required for the coil to...
  8. hevans1944

    Boost line voltage for LED Florescent bulbs

    Yeah, that statement gave me pause too after I wrote it. I think it is technically true because the primary and secondary, considered alone, are galvanically isolated no matter what external connections are made. Connecting one end of the secondary to one end of the primary does not, per se...
  9. hevans1944

    pre amplifier/ line in mixer chip

    Bluetooth data rates are about 2.1 megabits per second. See this link. And, yes, I would like to have a Bluetooth link to listen to audio from other electronic sources, such as television or my cell phone, without assaulting the ears of people with "normal" hearing. No problemo designing my own...
  10. hevans1944

    Boost line voltage for LED Florescent bulbs

    You are mistaken. The primary of the transformer connects between the "hot" line and "neutral". The secondary of the transformer connects between the "hot" line and the load. The other side of the load connects to neutral. Depending on how the secondary is "phased" with respect to the "hot"...
  11. hevans1944

    Schottky rectifier

    Well, there you go. One man's low power could be another man's low signal. I guess we will just have to leave it at that. @(*steve*) I was attending an Arduino class last night at the Dayton Amateur Radio Association club house when I noticed someone driving a slide with a small Superior...
  12. hevans1944

    pre amplifier/ line in mixer chip

    I would love to design a pair of Bluetooth digitally programmed hearing aids with DSP to filter out background noise and perhaps enhance response to speech to match my ears. These are available commercially of course for several thousand dollars per ear. What a rip-off! The Bluetooth interface...
  13. hevans1944

    Help with light detection keyboard

    @Gryd3 the OP only needs ten "keys" but the logic can process these any way desired, including chorded keying if that makes any sense while working underwater.
  14. hevans1944

    Boost line voltage for LED Florescent bulbs

    @CDRIVE the transformer primary is wired in parallel with the mains feed, not in series with the secondary. The secondary is wired in series with the "hot" side of the mains feed, in series with the load. The current limitation of this "boost" configuration is determined by the secondary current...
  15. hevans1944

    Help with light detection keyboard

    Please let us know how this turns out. I would like to know if you are able to exploit "total internal reflection" at the plastic-water interface by pressing a finger (under water, of course!) against the plastic. No need to submerge to great depths. The index of refraction of water does not...
  16. hevans1944

    Help with light detection keyboard

    I don't think this project is practical without some experimentation. Depending on a single sensor to detect light at 40m depth is asking a bit much. You will most likely need an emitter/sensor pair. There is one thing that might be used to advantage here: total internal reflection at the...
  17. hevans1944

    Schottky rectifier

    You could be right about the applications. The only RF work I have found (so far) relates to recent work on RF power conversion to DC using a Class-F RF power amplifier and synchronous rectification at 985 MHz. See attached PDF file. I was thinking I had seen some applications as mixers or...
  18. hevans1944

    pre amplifier/ line in mixer chip

    After years of exposure to high-volume rock and roll, my ears are no longer "golden" (if they ever were). Still, I can appreciate (to a certain extent) the audiophile's desire to approach perfection. Fortunately you are in good company with the wizards at Texas Instruments, who absorbed the...
  19. hevans1944

    Schottky rectifier

    Well, we still haven't explored synchronous rectification using MOSFET switches. I know such circuit exist, but I have no knowledge of the details. I suspect their main use might be for RF mixers and detectors rather than power rectification. Maybe someone will jump in here to enlighten us!
  20. hevans1944

    Schottky rectifier

    Oops. I sure hope the OP comes back and tells us what they are trying to accomplish. Apologies to Steve.
Top