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  1. MrBananas

    how to save in binary format, without mat extension

    Use fwrite. type "help fwrite" at the command line to see how to use it. Should be able to read the file with a simple C program. Also, you can export csv and excel files with csvwrite and xlswrite.
  2. MrBananas

    Help with MOSFETs

    Ditto with the above comments on drive circuitry. FETs need to establish an electric field to control current flow. As you may remember from physics, the voltage on a capacitor doesn't change instantly, you have to transfer charge for the voltage to change. The more current your driver...
  3. MrBananas

    Audio noise with op-amp. Need recommendations.

    Is the input AC coupled to the cable to block DC? DC bias from the previous stage if present could cause some hum in the output. Also, are you using two supplies (pos and neg)? Opamps don't operate rail-to-rail so that could be messing up the signal if it is AC coupled or goes within about...
  4. MrBananas

    Convert binary code to analog signlal

    What type of analog signal? If you are trying to convert the bitstream to something that you would see over a communications channel, you may need to consider quite a few things such as modulation type, encoding, etc. There is no "direct" conversion between digital and analog signals in the...
  5. MrBananas

    How do I measure bit error rate?

    Make sure to note that the noise power is often more important than the noise amplitude in most comm systems.
  6. MrBananas

    ttl output to cmos input

    Why not put a 2.9V signal zener across the CMOS input and just feed it with the TTL output through a series resistor to limit the current through the zener? Another possibility might be to use a voltage divider network with maybe a 3.1V zener for protection only. The input impedance on CMOS...
  7. MrBananas

    Free Energy from Motionless Electromagnetic Generator

    The first post above said the device outputs 100 times more energy than is input...that makes it over-unity, not perpetual motion. An amplifier also produces more power than is input from the signal source. It gets power from the supply. From what I understand about the theory behind these...
  8. MrBananas

    Voltage drifting

    Differential Amplifiers are your friends... If you use coax cable you can use both the signal and shield as inputs to a differential amplifier. The "noise," whether coupled in AC, RF, etc. will then likely show up as "common mode" (present on both inputs). The differential amplifier will give...
  9. MrBananas

    Broken Agilent Function Generator

    We have an Agilent 33120 function/arbitrary waveform generator that someone applied -15V to the AM modulation input on. We are trying to repair it, but the repairs haven't been going too well. We have schematics, but when the generator turns on, the display comes on with every symbol...
  10. MrBananas

    Anechoic chambers, fire suppression, insurance, etc.

    Anechoic chamber foam is basically carbon dust embedded in polyurethane foam. The funny thing about polyurethane foam is that it releases cyanide gas when it burns. Halon is the agent of choice, but of course that can't be obtained anymore, but there are some other choices as well, such as...
  11. MrBananas

    Non-uniform noise distribution ruins filter attempt

    I recommend looking into a technique called "Multirate Filtering." It is a DSP technique and it sounds like you are oversampling already, which is necessary for Multirate. It is a very common technique used in these sorts of situations where you have some wild data and you need to extract the...
  12. MrBananas

    Encryption - Password Sofware

    Encryption does not necessarily make the file size significantly larger. The reason for size increase is due to the fact that encryption algorithms are typically block encryption algorithms. RSA (asymmetric key-sender and recipient have different keys) and AES (symmetric key-same key used both...
  13. MrBananas

    AC/AC Converter Design

    This would be a one-time build item, and will serve as a laboratory power supply. That's why we need the large frequency range of operation. Thanks for the AC drive suggestion itsmoked. Unfortunately we don't use a lot of motors so we don't have any AC drives laying around. I'm still...
  14. MrBananas

    AC/AC Converter Design

    I am trying to generate 1000Hz, 3-phase, 36Volt RMS, 200W total power system from 60Hz single phase line. Motor-generator or commercial solution not practical (expense). We would like this power supply to operate over the range from 60Hz-1000Hz, so transformer designs are probably out as...
  15. MrBananas

    Unbalanced Sinking/Sourcing of PICs

    The reason for the voltage rise on the output pin is due to the drain-source on-resistance of the PIC output transistors. You will have the same problem with external transistors as well unless you either get logic level FETs with low on-resistance or perhaps put some BJTs in saturation...
  16. MrBananas

    protecting analog input of microcontroller

    A cap will help with high frequency transient spikes, but in the case of (relatively) low frequency transients you would be wise to have some zener diodes of the appropriate zener voltage there as well. When the voltage on the input pin exceeds the zener voltage they "clamp" the pin voltage...
  17. MrBananas

    Breaker size

    I would guess that for some reason whoever designed the system wanted any problem to trip the breaker in the main MCC. Typically the circuit breakers on the destination side of branches are rated less than the source so that the breaker closest to the problem blows first.
  18. MrBananas

    Motor Controller Fundamentals

    Your motor controller probably utilizes some type of switching power converter (PWM buck, etc.) to alter the output voltage, otherwise the system would be terribly inefficient. As a result, the current at 12V is not the same as the current that flows throught the batteries. Assuming perfect...

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