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  1. hevans1944

    Advice needed: Name that part ?

    I saw that, too, but also saw R103 and below that R105 with no clear indication of what those labels referred to. It could very well have been a chip inductor. I am not very familiar with what those look like, but IIRC Coilcraft sells them and some do look like inductors... and some look like...
  2. hevans1944

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    @Xeno Xenox, I am gonna take a wild-ass guess and say you are probably really good with topology, too. Thanks for the explanation. It has never occurred to me that everything can be looked at from all sorts of different perspectives and projections, although during every-day life, I think I at...
  3. hevans1944

    Building a homemade LCR meter

    The explanation of "how this circuit works" can be found here. It is basically an LC oscillator whose frequency is measured with a microprocessor and converted to an inductance or capacitance value that is then displayed on the LCD. When measuring capacitance, a fixed inductor is switched in to...
  4. hevans1944

    Location devices

    You need to be more specific about the separation distance and the accuracy and resolution required to sound an alert or an alarm. For example: devices must be battery operated, 3 V coin cell preferred; range must be programmable from 10 feet to 30 feet with a resolution of one inch and an...
  5. hevans1944

    Advice needed: Name that part ?

    Looks like it could be a 22 ohm resistor surface-mount device (SMD). See if you can measure the resistance. It probably overheated and melted the solder from too much current flowing through it. It may not be bad, You may be able to re-flow solder this, or a replacement, back onto the pads it...
  6. hevans1944

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    I thought a hyper-cube rendered in 2D looked like a cube nested inside a larger cube with lines connecting the eight corners of each cube. Most of the time I have seen this done with wire frames and soap bubbles. Still, digitally generated Lissajous figures are fun to play with. Good job, and...
  7. hevans1944

    My Modified Router

    I think modifying an FCC type-approved product is "risky business" unless you are licensed to do this sort of thing. Oh, wait! No FCC in Australia, so I guess anything goes... perhaps @davenn (our resident microwave expert) can chime in with an opinion on this. Welcome to EP, Christian! I like...
  8. hevans1944

    Complete electronic virgin!

    When I can purchase an after-market add-on (which is what the OP is proposing) I will believe it is "well beyond experimentation". For now it is just a marketing gimmick with lots of warts that advertising tries to cosmetically cover up. They are prepping us for "driver-less" automobiles with...
  9. hevans1944

    Convert 15v turntable to 12v

    Oh, please do explain why you want to run your turntable on 12 V DC. Let us be the judge of what is irrelevant. Also please explain why you think the turntable motor operates on 9vdc when the manufacturer's literature says the turntable motor is a synchronous AC motor that gets its power from...
  10. hevans1944

    Convert 15v turntable to 12v

    Nope, it already runs on 15 V and OP wants it to run on 12 V. I like the idea of hooking it up to a 12 V DC power source to see if it still works at the reduced voltage. But, as you noted, more information on the turntable would be necessary for a definitive answer.
  11. hevans1944

    Help needed on simple short circuit protection

    Without knowing anything about CE/FCC certification, and the testing protocols for compliance with same, it is impossible to recommend a solution. However I am sure there are laboratories you can hire who will do just that and explain why your product passes or fails. I would take my fishing...
  12. hevans1944

    Mixed voltages at negative common connection?

    I see nothing wrong with that. What is the battery used for? Are you going to charge it from the PV panel with a buck converter between the PV panel and the battery? That will work.
  13. hevans1944

    Getting value of ADRESH out of a pic μcu?

    Some more observations on "shifting" to obtain a multiplication result: In the decimal or base 10 number system, we "shift" the decimal point to the right to multiply a number by powers of 10. So 1234. becomes 12340. Similarly, "shift" the decimal point to the left to divide a number by powers...
  14. hevans1944

    Need help with android app for Bluetooth device

    All I know about it is what I read on the Internet. Looks like it uses a Bosch BMI160 inertial navigation sensor providing linear acceleration as well as rotation rate (rate gyro) on three mutually perpendicular axes. That's way more than you need to instrument a spinning top, which only needs a...
  15. hevans1944

    Getting value of ADRESH out of a pic μcu?

    Close, but no cigar! 0000 0001 multiplied by 256 is 1 0000 0000. Or regrouping the digits for base eight, 100 000 000 which I suppose you could read aloud as one hundred million. But nobody I know does that. And base eight notation died a deserved death in the twentieth century. You have to...
  16. hevans1944

    Getting value of ADRESH out of a pic μcu?

    I watched it on TV. You guys made the national news. Are you still dry? The PCB arrived in the afternoon mail! Yes, the regulator holes need to be enlarged. Will work on getting parts mounted in the coming week. The board looks great! Wish I could still do this kind of work. <sigh> The two bits...
  17. hevans1944

    How to control the speed of a 24vdc pump from circulating water temperature?

    Here is a similar, somewhat less expensive PWM controller. The photos do not all appear to be from same product. Note the absence of the metal mounting ferrules at the corners on two of the images. There is also some sort of power semiconductor device mounted near the 3-pin potentiometer...
  18. hevans1944

    LM318N comparator circuit

    The problem is op-amps are designed to be used in closed-loop, negative feed-back circuits where the differential voltage between the two inputs stays small (because of the negative feedback). When used as a voltage comparator, the op-amp operates open loop and differential inputs can be several...
  19. hevans1944

    how do i drop voltage of a power supply

    The forward voltage drop across each diode will be approximately 0.6 V to 0.7 V at 5 A current. So to drop 29 V to 25 V you need to drop 4 V across the series-connected string of diodes. Do the math: 4 / 0.7 = 5.7 ==> six diodes, or maybe seven diodes if 4 / 0.6 = 6.6. This is a "quick and...
  20. hevans1944

    LM318N comparator circuit

    Pretty easy to blow up a zener if (1) you apply reverse bias far in excess of the zener voltage and (2) fail to provide a sufficiently large value of series current-limiting resistor. Good call telling him to use the output of LM318 directly. Although I sometimes use op-amps as comparators, I...
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