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  1. BobK

    Time to start building grow lights!

    I have seen much more of that kind of behavior related to alcohol. Bob
  2. BobK

    Book for radio data transmission

    If it is very low data rate, you might want to look at power line communication instead of wireless. Bob
  3. BobK

    Air actuated switches

    How fast a response would a thermistor give? If he want to turn on the heater only when you inhale, the response has to be pretty quick, not seconds. Bob
  4. BobK

    8-channel audio player

    If you need the tracks to be synchronized, I don't think you will find one easily. Bob
  5. BobK

    Cons of using large transistors?

    You would have a hard time finding at transistor with a max Vce of less than 24V. But if you mean using power transistors where a small signal transistor is called for yes, there are disadvantages. The power transistor will have lower gain lower frequency response and higher junction...
  6. BobK

    Time to start building grow lights!

    I see you are in Arizona. Your resolution just missed. Bummer. Bob
  7. BobK

    Time to start building grow lights!

    Today, in my state of Massachusetts, it became legal to grow pot (indoors only) for personal consumption. I think the market for grow lights is about to explode! Bob
  8. BobK

    Cant get a voltage reading off an working AC/AC Adaptor with a multi meter ?

    The 12V is likely just the output of a transformer and isolated from earth ground. You can measure the 12V AC on the ac scale by using either lead on the barrel and the other on the inside. But we are way past that anyway. The device works on the 12V AC adapater. And I already explained in...
  9. BobK

    40 Hz LED

    Hey, if you look at some of the research that gets funded... I'm just sayin' Bob
  10. BobK

    USB Wifi Dongle Issue

    You've got more patience than I over a $10 dongle. But perhaps that is because the lovely wife Morticia would have definitely returned it for a refund. Bob
  11. BobK

    40 Hz LED

    That would be interesting to see. It will probably work for quite a long time. Steve's research just showed that the beta deteriorated when exposed to repeated breakdowns, but that might not matter for the relaxation oscillator. Bob
  12. BobK

    Signal amplifier

    An audio amp should do the trick. One that is designed to run a speaker from a headphone jack. Bob
  13. BobK

    Blinking lights with RF from nearby cell phone antenna

    Why would you expect the LED to blink? If that circuit works at all, it would simply light the LED whenever a sufficiently strong radio signal was detected. Bob
  14. BobK

    Low power distance detection

    If both objects have a transceiver, you could send a signal from one and have the other respond with a known built in delay. When the original transmitter receives that response signal, it has a time difference that is that known delay + twice the distance x the speed of light. No...
  15. BobK

    40 Hz LED

    Oh, maybe you are talking about using the Vbe breakdown voltage to make a relaxation oscillator? As Steve showed in a major research project, this will destroy the transistor eventually. Bob
  16. BobK

    40 Hz LED

    I'd like to see that circuit. Bob
  17. BobK

    Headphones from amp speaker wires

    The speakers are polarized so that when you use more than one (like in stereo) they move in the same direction at the same time. The signal to the speaker goes both negative and positive, one makes the cone move out and the other makes the cone move in. If you have a stereo, try reversing...
  18. BobK

    LCD display on EST2 Fire Alarm Panel only display black boxs ... how to fix

    This is what that type LCD display does if it does not get the initialization code. I suspect that the problem is not with the display, but with whatever is trying to communicate with it. Edited to add: Actually it can also look that way if the contrast setting is too high. Is there a...
  19. BobK

    Cant get a voltage reading off an working AC/AC Adaptor with a multi meter ?

    There is actually a big difference between powering it with 12V AC and DC. After going through the bridge rectifier, the AC supply nearly 16V DC, whereas the 12V DC input will result in less than 11V DC. I suspect that difference is why it is flaky. Bob
  20. BobK

    Cant get a voltage reading off an working AC/AC Adaptor with a multi meter ?

    If the unit operates off AC or DC it has a bridge rectifier inside and it can take AC or DC with either polarity. Did you check the output of the 12V DC adapter with your multimeter? If the voltage is right, I don't see why it would not work. Bob
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