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  1. hevans1944

    complex number

    Complex numbers are a mathematical construct, used to represent two orthogonal sets of numbers named "real" and "imaginary". There are many orthogonal sets possible. For example, the sine and cosine functions are orthogonal to each other. This is useful because there are many situations in the...
  2. hevans1944

    Need to find a way to do different functions basedon incoming voltage

    Connect a relay with a 24 V DC coil and SPDT contacts to your circuit that supplies either 12 V DC or 24 V DC to the relay coil. Also connect the common contact of the SPDT contacts to this source of power. Now, if 12 V DC is applied to the relay coil it will be insufficient to energize the...
  3. hevans1944

    Sanyo Clock radio repair

    The alcohol will de-lubricate the slider interface to the potentiometer as it dissolves and washes away whatever junk has accumulated. That's why you should follow up with a little bit of CAIG DeoxIT Fader F5S-H6 Spray after cleaning. This will add a small amount of lubricant, but hopefully not...
  4. hevans1944

    Sanyo Clock radio repair

    I have never used the product, but it looks like a typical electronics solvent. My favorite is a 50-50 mixture (by volume) of 99% isopropanol and trichlorethylene (TCE). Unfortunately TCE is banned from use for electronics cleaning now. In the Air Force we would soak 20mm Gatling gun barrels in...
  5. hevans1944

    Choice of Op-Amps

    If you have ever had the opportunity to observe industrial robots in action, the servo motor noise is incredible. Of course the noise in most factories that employ them is even louder. In the Air Force everything we used was powered from 400 Hz AC. This was bad enough, but add in two-phase AC...
  6. hevans1944

    Sanyo Clock radio repair

    You can get by with 91% isopropyl alcohol. Cost is a few dollars a quart. Just be aware that as soon as you open the bottle it starts to absorb moisture from the air. That means an open bottle doesn't remain 91% for very long! Anhydrous 99% isopropyl alcohol is not normally available...
  7. hevans1944

    Choice of Op-Amps

    Apparently PWM causes motor hum. Hmmm. I wonder if the PWM frequency is too low... isn't it supposed to be in the multi-kilohertz range, above human hearing? I know stepper motors push out a terrific scream, PWM or not, but that's because their stepping rates are in the audible frequency range...
  8. hevans1944

    Choice of Op-Amps

    The FAN3100CSX is a digital device, a gate driver for N-channel MOSFETs operating in switching mode. It will not work for your application which requires a continuously variable DC output. If the non-inverting gain of the TL071 is 2.4 and the input from the RC filter is 1 to 5 V DC, then the...
  9. hevans1944

    Control 24v stepper with motor shield

    Good luck with that. Can you post a picture of whatever circuit you come up with that works? I have a Superior Electric Slo-Syn DC/Synchronous stepper, model MO61-FD08, that I would like to drive. It is rated 1.25 V @ 3.8 A so I think I will need a PWM modulator and maybe 12 to 15 VDC to drive...
  10. hevans1944

    Velocity/Accelerometer w/Digital OP??

    Perhaps a GPS receiver will work, if you can get a good signal. Takes a few minutes to lock-in but after that most GPS receivers will report changes in position on a regular basis with a sensitivity of a few feet. More accurate position tracking is possible with mind-blowing data-signal...
  11. hevans1944

    Control 24v stepper with motor shield

    If you have the technical acumen, you might consider hacking the seeed motor shield. It uses a L298 dual H-bridge driver that is specified to run with motor supply voltages up to 40 VDC. I can't find any schematics for the seeed motor shield, and I don't care to reverse engineer their Eagle...
  12. hevans1944

    Power Source Advice/Help

    The current rating of the wall-wart will undoubtedly be larger than 0.02 A (20 mA). Doesn't matter. The wall-wart current rating is what it could supply to a maximum load. The actual current the wall-wart does supply to any load can be anything from zero up to its maximum rated current. So just...
  13. hevans1944

    solonoid controler

    Well, actually you did, in the first sentence at the top of your first post: "You can use a capacitor and a single pole dual throw (changeover) switch." Sorry, I missed that.
  14. hevans1944

    Power Source Advice/Help

    The power requirements are modest: 4 to 25 VDC at 0.02 A. Just about any wall-wart providing 6 to 12 VDC should work. You will have to cut off the "computer power plug(s)" and connect the red and black wires from the digital display to the wall-wart cable. The wall wart will have a barrel plug...
  15. hevans1944

    solonoid controler

    Well, it confused me too, until @BobK pointed out the model parameters. Now all we need is a Digi-Key part number for S1 and S2. Well, actually all you need is one SPDT relay with coil operated by V2. Connect common contact to L1, NC contact to "ground" or common, NO contact to V1. Apply V2 and...
  16. hevans1944

    12VDC to 100DC is it possible?

    My oldest daughter has a Prius. She seems to like it, but it does depend on its tiny internal combustion engine to keep the battery charged. AFAIK, there is no successful electrical car that depends solely on an external electrical charging source. Takes too long to recharge (even with a 220 VAC...
  17. hevans1944

    Combining multiple amplified outputs to feed one speaker only

    Well, they're your radio and your acoustic variometers aren't they? Gliding is sooo personal! Have you ever been to Albuquerque NM to see them hang gliding off a Sandia mountain top? There is a aerial tram that takes the gliders to the top from whence they jump off and ride the thermals coming...
  18. hevans1944

    Collect and export data using blue tooth

    Are you sure you want to "re-invent" this particular wheel? Have you visited this link? Google is your friend.
  19. hevans1944

    Combining multiple amplified outputs to feed one speaker only

    You didn't mention in your original post that this was an avionics application! I wouldn't touch that with the proverbial ten-foot pole. Only a qualified, perhaps licensed, avionics technician should work on avionics (aviation electronics). It's not like you can pull an airplane in flight over...
  20. hevans1944

    Help with transmit and receive sending

    The transmitter/receiver combination you anticipate using has a operating frequency (315/433 Mhz ) that is NOT authorized for Region 2, which includes the Americas (North and South), the USA and Canada. See the Wikipedia article. A better choice, IMO, would be an XBee Series 1 transceiver...
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