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  1. BobK

    Need some help about this edge meter

    So that would be 150uA full scale. Quite sensitive. Bob
  2. BobK

    Decoupling a cmos based 555?

    Decoupling has nothing to do with the stability of the power supply. Decoupling is needed when a chip might change it's current draw rapidly. When this is the case, inductance in the wiring can cause a glitch in the power, whether it is a battery or a regulated or unregulated mains fed supply...
  3. BobK

    voice module help please

    In the OP he states that the recorder module and amp have different batteries. Bob
  4. BobK

    How to control 80 relays using ardrino

    I would highly recommend using solid state relays for this. They will use far less current, switch faster, and not make annoying clicks every time they switch. Bob
  5. BobK

    voice module help please

    If the sound module itself is very low volume, I don't think there would be any problem with putting it's speaker output to an AUX input of another amplifier. The signal is likely in the 1V range, which is perfectly OK for an AUX input. The problem might be that the sound module does not work...
  6. BobK

    Electric skateboard battery

    No, not hydrocarbons, carbohydrates are the best fuel for a skate board. Bob
  7. BobK

    Can You Look at This and Tell Me Why It Doesn't Work?

    I hate to ask this, but do you have the thermostat set for heat or cool? If you have it set for heat, as shown in the picture, then it will come on when the temp is below the setting. I think you want it on cool. Bob
  8. BobK

    help to a beginner

    If the commands are nothing more complicated than turning devices on or off, a device like the one linked in post #2 does everything you need. If not, you need to give us more information about what you are trying to do. Bob
  9. BobK

    Wiring 100 speakers together, help!

    If you want 50 speakers on each channel the arrangement is different. You could put 10 strings of 5 in series and the resulting impedance will be 4Ω which is still OK with our amp. You could also put 7 strings of 7 for 49 speakers with 8Ω impedance. 20W is enough to overpower 100 0.15W...
  10. BobK

    Very Basic circuit but I am struggling

    Yep, I was only 55 when I picked up microcontrollers. I am now 63 and plan on taking the next step with FPGAs. Bob
  11. BobK

    Very Basic circuit but I am struggling

    As is your point. I was just trying to give another option. Not all of the info in the forum is for the OP, either, there are many readers who might like to see alternatives. But the real reason that I posted the uController idea is that I cannot think of a way to do exactly what the OP...
  12. BobK

    Help calculating the resistors

    Yes. Edit: BTW, if you used high brightness LEDs you could probably run them at 5mA or less and have the battery last 4 times as long. Bob
  13. BobK

    Wiring 100 speakers together, help!

    Wire 10 speakers in series. Do this 10 times so you have 10 strings of 10 speakers each. Now connect each string to the amplifier in parallel. I.e. connect one end of each string to the + output of the amp and the other end of the string to the - output of the amp. This will give you 8Ω...
  14. BobK

    Homemade Capacitor

    If he is going to do that why just buy a 1F capacitor? Bob
  15. BobK

    Very Basic circuit but I am struggling

    Simple is in the eyes of the designer. Someone with knowledge of microcontrollers would find using one for this project the simplest way to do it. And the OP gave no indication of their level of knowledge. How do you know that s/he is not experienced with microcontrollers? Bob
  16. BobK

    Resistor value

    Yes, the question is self contradictory. If It is 4A, and V is 160, then R3 has to be 40Ω. Bob
  17. BobK

    Very Basic circuit but I am struggling

    An 8 pin PIC could easily do this. You would have the three inputs connected to 3 GPIO pins (one of them being the MCLR pin which can only be an input. You would have the other 3 GIPOs connected through a resistor to the 3 LEDs. A slightly lower component count than Adams solution: 1...
  18. BobK

    AC circuit (120v single phase) smooth to a10 sec. average voltage sine wave

    I think you are trying to get a signal that is the variation of the line voltage from the ideal sine wave. What Hop suggested in post #28 is the way to do this. Another possibility is that you know the input is not a perfect sine wave, even without the glitches, and you want to isolate the...
  19. BobK

    Reduce amperage without reducing voltage. Diodes? [Noob]

    You probably have electrical outlets in your home. You can plug in a room heater which will probably take 10A or more. You can also plug in a night light which will take < 100mA. Does this tell you anything? Bob
  20. BobK

    Crossover circuit for a hybrid speaker I'm building

    Why do you think the speakers have to be in series? When you use a crossover, the impedances will not obey the rules for parallel resistors because the crossover will make them high impedance outside of the range that they are handling. The impedance of two 4Ω speakers with a correct crossover...
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