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  1. hevans1944

    LED Driver Wattage Question

    I would opt for the larger unit. The main difference seems to be the compliance voltage range since both are rated to deliver the same constant current. For a couple bux more and the same wait time, why chance having to purchase another one if the smaller one doesn't deliver the power you need...
  2. hevans1944

    Step Down DC Buck Capacitor Blow up

    That says it all. The product is defective because the maximum output should have been only 36 V. You measured 50 V. Clearly, the input polarity was correct, because the product did produce a DC output, albeit too much output. Demand a refund! Then buy a different replacement from a different...
  3. hevans1944

    Time to start building grow lights!

    No matter what laws the "sovereign states" put on their books, the Feds are adamant about treating marijuana as a "dangerous drug" with all sorts of penalties for use, possession, growing it, selling it... yada, yada, yada. NORML needs to get Congress to pass a law (or laws) that permanently...
  4. hevans1944

    LTSPICE Help needed to make transformer coupled amplifier & push pull amplifier

    Your LTSpice schematic doesn't look anything like the schematic you posted earlier. Edit the LTSpice schematic and try again. You might want to visit some of the links at this Google result page. As Harald has already asked (twice now): is this a school assignment, homework, or are you just...
  5. hevans1944

    Soldering wire to metal

    Flux is always necessary when soldering, but it must be the right kind. Never use plumbers flux or 50/50 tin/lead solder. You should use a tin/lead alloy solder with a built-in non-corrosive rosin flux core, 60% tin and 40% lead. You can also use a eutectic alloy of 63% tin and 37% lead, again...
  6. hevans1944

    Overkill LEDs and PWMing with electric switch

    Holy cow, @Bluejets! That's one nice little MOSFET! Time to buy a ten-pack of these with free Prime shipping from Amazon to supplement my stock of 2N7000 puppies. You adventurous types can look on eBay for better prices. Here is a link to the Fairchild Semiconductor datasheet. Impressively low...
  7. hevans1944

    Low power distance detection

    Yep. Without a co-operative signal returning to the transmitter (think RADAR), distance measurement is very difficult. Heck, GPS is basically just a distance measurement between a very accurate clock in three (or more) transmitters and a passive but intelligent receiver.
  8. hevans1944

    Low power distance detection

    Lots of problems. First one is this: how do you maintain synchronism between the transmitter oscillator and the receiver oscillator that is doing the counting? Others have made reference to an atomic clock (rubidium or cesium or whatever) and that would work for awhile until the two clocks...
  9. hevans1944

    Resistor colour code

    0.62 ohms might be hard to measure with a multi-meter. You could connect it to a constant-current source and measure the voltage drop to verify the resistance. No constant current source handy? Just wire it in series with a 100 ohm resistor and connect the series pair to a constant voltage...
  10. hevans1944

    Temperature sensor

    Yes, that is why the input radiation field must be optically modulated (chopped) for comparison against a reference field. As long as the object whose temperature is being measured is not at the same temperature as the chopper blades, a signal will be observed at the modulation frequency. A...
  11. hevans1944

    Temperature sensor

    Not yet! Got the 26-foot Penske truck loaded, but we still have stuff left over that we want to take to Florida. Gotta pack some more cardboard boxes and see if we can (somehow) fit them on top of what's already in the truck. So, I took a break last night to see what's going on here... hard to...
  12. hevans1944

    Resistor colour code

    Or, if it really IS a resistor: 0.62 ohms. 62 is the two significant figures from blue and red bands, silver band means multiply significant figures by 0.01, gold band means 5% tolerance; ignore the black band. If it IS an inductor, as Harald mentioned, 0.62 μH is a quite small value. You may...
  13. hevans1944

    Temperature sensor

    The problem with monitoring a specific area (3 feet by 3 feet) from a specific distance away (1 foot) is field-of-view (FOV) of the sensor. The FOV must be large enough to capture the entire area, yet not too large lest the sensor also "sees" the surrounding area or the background behind the...
  14. hevans1944

    Need Hardware list for 5-Dot-Matrix printing with Wifi-Modules

    You might be able to get the WiFi to work with the "command car" but I think it should then communicate over a low-power Bluetooth link with the other four cars. You can purchase Arduino shields with Bluetooth modules ready-to-install. Program all five of them as a mesh network and use another...
  15. hevans1944

    DVD

    Not even close. Try perusing the links at this Google result page.
  16. hevans1944

    Shift Register circuit validity

    That helps. The only possible change I would recommend is connecting OE to one of the RPi output pins and activate it after all the segment data has been shifted in and a strobe pulse has been issued to update the 7-segment display. You can also use OE as a pulse-width modulated intensity...
  17. hevans1944

    Why don't I get a Sine wave?

    And yet another testimonial to "simulating" with real components. Bob Pease still lives in the analog community!
  18. hevans1944

    help me pick out the right type of diode

    Thanks, Bob. For some reason (senility?) I didn't even think about using isolation diodes in series with each battery. That's a pretty good solution if you don't mind the power waste under load. As you said, the OP needs to know the full load current, and should probably use a Schottky power...
  19. hevans1944

    Shift Register circuit validity

    You should create a real schematic with standard symbols and standard drawing conventions. Most of us here won't take the time to reverse engineer a Fritzing wiring diagram to create a schematic. Fritzing is, IMHO, for "monkey see, monkey do" efforts only.
  20. hevans1944

    help me pick out the right type of diode

    I cannot imagine any diode circuit that would prevent a bank of paralleled SLA batteries from discharging into one with lower than the average terminal voltages of the remaining batteries. Show us a schematic of what you have in mind before going off on a quest to find "the right diode (type and...
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