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  1. hevans1944

    What the latch?

    A flip-flop (NOT a flip flip, whatever that is) retains either of two stable output states and thus exhibits memory. A (hex) inverter responds in real time to an input logic state by inverting that state without any memory of previous states: Thus if input = 1, output = 0; if input = 0, output...
  2. hevans1944

    TTL logic based Question

    Well, the TI datasheet says the emitter inputs sink 0.4 mA when low. Does that help with your circuit analysis? Why would an exam care about the internals of an ancient and obsolete logic integrated circuit? What is the exam for? Just curious. I am afraid I can't be of more help.
  3. hevans1944

    TTL logic based Question

    Read this article and then apply circuit analysis techniques. Is this a homework problem?
  4. hevans1944

    What's this ?

    Looks like it has been applied to a soldered connection of solid wire, so it may have been applied as a "strain relief" coating to prevent the wire from breaking as a result of vibrations.
  5. hevans1944

    Circuit design help for blind dog

    I think you would be better off putting a receiver in the ball, along with a small piezo-electric speaker transducer. Something on the order of those talking greeting cards but without the recording, substituting instead a small FM receiver. This would allow you to play the audible "hints" at...
  6. hevans1944

    What the latch?

    I think perhaps they were thinking of wiring pairs of them as RS latches. See @Pyramid's post #11. I've done this many times, usually for de-bouncing SPDT switches... and you don't need the resistors shown in the schematic.
  7. hevans1944

    New to electronics, have a basic build

    I can see where a kitchen scale that talks to my cellphone would be a hot ticket item at Bed, Bath, & Beyond. For example, I recently purchased this one on sale at a local upscale grocery store for around fifty bux or so. It has all the features I need to measure out portion-controlled servings...
  8. hevans1944

    New to electronics, have a basic build

    I bought two Arduno Uno and two XBee modules to test a point-to-point communications application. Upside is there is plenty of support on the web for this. Downside is it won't talk to cell phones or PC Bluetooth transceivers. Make Google your friend and do a search on Xbee versus Bluetooth for...
  9. hevans1944

    Fixing an HP3455A multimeter

    Or, as they say in the McChicken business: parts is parts.:eek:
  10. hevans1944

    What the latch?

    I like this thread... brings back fond memories of mid-20th Century technology. Of course you could implement this with a handful of PICs. There might be some fun in that.
  11. hevans1944

    Howdy all.

    We have quite a few jokers that lurk here and chime in once in awhile. Welcome to Electronics Point wannabe submariner!
  12. hevans1944

    sensor help?

    How do you use an RFID tag to determine that the ball crosses the goal line? Put the interrogating transceiver at the back of the cage? Could work if there were never any false positives. Maybe embed the transceiver antenna in the cage framework? RFID is worth a try.
  13. hevans1944

    dimmer circuit problem

    In your original "circuit diagram" you have the source voltage on the left connected directly to the load on the right. The triac, if it conducts at all, shorts the input supply voltage. Poof! Why are you messin' around with 220 V AC mains current when you apparently lack the knowledge to...
  14. hevans1944

    sensor help?

    The cheapest way to sense when a soccer ball crosses the entrance plane of the goal cage would be to photograph the goal in real time with one or more video camera(s) having a sufficiently high frame rate. Then use real-time digital image processing of sequential frames to determine when the...
  15. hevans1944

    Advice on becoming an engineer?

    I was advised by a fellow technician and mentor early in my career to pursue an engineering degree. Both of us were well-paid technicians performing engineering work, but he said I would earn more respect and have better job opportunities later on if I had that "paper ticket" that said, "Golly...
  16. hevans1944

    very basic (general) microcontroller programming question

    Sorry for the confusion. Perhaps you could explain what the following statement means. Many of us here have been programming microprocessors for many years with various languages and application development interfaces. I learned the rudiments of programming in the 1960s and jumped on the...
  17. hevans1944

    very basic (general) microcontroller programming question

    Yes, if you want to program at the register level. No, if you want to program in a higher-level language such as C or even BASIC. As for portability... that depends on how wedded your peripheral circuits are to a particular microprocessor's internal hardware capabilities. But that's why drivers...
  18. hevans1944

    Nixie tube clock: display flickering, buzzer crackling

    A schematic diagram, if you have one, could also be helpful. I agree with Harald: suspect ALL the solder joints since you were a newbie with shaky hands when you assembled this kit. Now that you hopefully have more experience with soldering, suck off the old solder with solder wick (one joint...
  19. hevans1944

    LED IR

    Photo diodes work best when reverse-biased and connected to the summing junction (inverting input) of an op-amp. With the non-inverting input connected to circuit common, the summing junction becomes a "virtual" ground. You connect a feedback resistor from the output to the summing junction to...
  20. hevans1944

    Looking for an appropriate RF IC

    Perhaps you should read this article taken from a link on this Google results page. Oh, and welcome to Electronics Point!
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