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  1. BobK

    wind turbine project

    Surely you are joking? $785? Bob
  2. BobK

    problem programming pics

    Almost, retiring at the end of April. And despite our quite reasonable income, my wife shops mostly at consignment stores. Though she does have a weakness for 5-star hotels when we vacation.:) Bob
  3. BobK

    Ultrasonic Sensor Help

    Your 40KHz centered transducer is probably capable of receiving signals quite a bit wider than that, but at reduced response. But then you put a 40KHz bandpass filter that will attenuate anything other than 40KHz. Lose the bandpass filter and you will get a wider response. Not sure if it will...
  4. BobK

    Problem with Interrupts - PIC18F1220

    volatile serves a couple of purposes and is very important in microcontroller programming. What it means is either of 2 things: 1. Changing this variable has side effects which are not obvious via analysis of the program. As an example, many hardware registers are used on PICs. Say...
  5. BobK

    Control stepper motor with PIC, maximum output frequency of PIC

    Actually, if you use the PWM module, you can probably put out a square wave at the 1/2 of the clock frequency. But it would probably be impossible to control the number of steps accurately since you could not use interrupts at that rate. I would say that a PIC could reliably put controlled...
  6. BobK

    Can i Send gps (nmea) data down a AUX plug?

    It is certainly possible. The only question is at what bit rate and accuracy. Back in the bad old days, working from home meant using an acoustic coupler on the telephone line at 1200Baud. I would think that you could achieve that rate. Bob
  7. BobK

    Control stepper motor with PIC, maximum output frequency of PIC

    The motor datasheet does not include a max RPM, but the graph shows step rates only up to 1000 per second. The PIC can do that rate without even breaking a sweat. In fact, I can do that while having nearly it's full compute power for doing other things. Bob
  8. BobK

    problem programming pics

    You need to set various configuration options in any PIC project. As Adam hinted, the oscillator selection is often external RC for PICs. You need to select the internal oscillator. Also you need to turn off the watchdog timer in configuration settings. I am at work now and do not have...
  9. BobK

    Science Fair Project

    WIFI would be overkill an use too much power. Bluetooth would be a better fit. Oh, and to make it small and cheap, I hope you are planning on production in the 10s of thousands or more. Bob
  10. BobK

    wind turbine project

    That is an interesting choice. Can you link to the motor you bought? Bob
  11. BobK

    Moving electronic part/switch/relay - does this exist?

    I think what would be needed would be a solenoid coupled with some mechanics that would give the latching of two states. Something like in a click-type ball point pen. However that is very small. (particularly since it is a square, which is two dimensional :D.) Bob
  12. BobK

    Which battery is suitable?

    I would look for a module that is specified as an RF remote. A transmitter / receiver alone will not have much noise immunity, and being next to a brushed motor is a very noisy environment. Also, higher frequencies are better noise-wise. I would look for 1.2GHz ones. Bob
  13. BobK

    A little question on audio amplifiers..

    You design the circuit such that it can handle the max output, but saturates at a lower output, maybe half the voltage. Or, you add a sensitivity control that allows one to adjust to the current listening level. Bob
  14. BobK

    Problem with Interrupts - PIC18F1220

    I work with PICs enough that it is automatic to turn off analog first thing. There is a good reason why they do it. If an input pin is connected to an analog signal which happens to be around Vdd/2 when the PIC comes up, it could cause shoot through it the pin were set to digital. Bob
  15. BobK

    Problem with Interrupts - PIC18F1220

    Any of the pins that can be analog inputs are configured as analog on reset. You need to make B0 a digital input by turning off the analog feature. Try: ADCON1 = 0x70; In your PORT setups. (See example 10-2 in your datasheet) Bob
  16. BobK

    Hold 5v Line

    This circuit is basically what I was suggesting, substituting a Schmitt trigger for the comparator. Bob
  17. BobK

    Which battery is suitable?

    At any given voltage your motor is going to spin at a certain speed. Batteries in series: the voltage adds but the capacity in maH does not. Batteries in parallel: The capacity in maH adds but the voltage does not. If you use 3 batteries in parallel, the motor will run at the same speed...
  18. BobK

    Stage Line 500W amp repair project

    So the short is not caused by Q46. It is either R118 or something on the circuit board traces. With all due respect to Kris, I would still suggest that you pull one leg of R118 and see if it is shorted. But first maybe inspect the other side of the PCB to make sure there is no solder bridge...
  19. BobK

    Android Mirror on PC Using MicroController

    How is the data to be sent from the Android device to your adapter? Bob
  20. BobK

    A little question on audio amplifiers..

    P = V^2 / R V = SQRT(R * P) So a 100W amp driving an 8 Ohm speaker, the RMS voltage is SQRT(800) = 28V. But that voltage will only be attained when the amp is putting out max power. Typical voltage is likely < 10V. Bob
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