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  1. S

    Multi-channel RMS-DC converter???

    Hmm, guess not... maybe ill use an analog multiplexer into a single RMS-DC converter instead. Will this work OK? Sam
  2. S

    Multi-channel RMS-DC converter???

    Hi, I'm just wondering if anybody has ever come across an RMS-DC converter IC that has multiple inputs. I need to convert 7 AC inputs to an RMS equivelent. Thanks, Sam
  3. S

    How to measure the voltage between earth and neutral ?

    Re: Need 3-phase help quick The problem is that I have to measure Neutral-Phase voltages using the same ADC. so the ADC's ground reference will be neutral for the other voltages. Can I connect the 3-phase Earth straight to the circuit ground? wont this mess with the measurement's accuracy...
  4. S

    How to measure the voltage between earth and neutral ?

    Re: Need 3-phase help quick The ADE7754 looks great, but its a bit of an overkill for what i need to to, and it still seems to only support up to 4 wire 'wye' configuration. I need to measure between earth and neutral too. All I need is voltage and current measurements, and my main concern is...
  5. S

    How to measure the voltage between earth and neutral ?

    Need 3-phase help quick Hi, I've already posted a similar question to this recently, but I need to get this sorted pretty quick because i have a uni report due in a couple of weeks. I'm working on a 3-phase power monitoring system. the power to be monitored is wye connected with an earth and...
  6. S

    How to measure AC voltages using ADC on an AVR micro?

    Re: AC voltage - ADC Thanks for the replies. I checked out the chips, and they look perfect for the job. My only concern is that the cost might start to add up once ive installed one for each voltage and current measurement in a 3 phase system. but i guess thats life... Sam
  7. S

    How to measure AC voltages using ADC on an AVR micro?

    Hi, I'm wanting to measure AC voltages using the ADC on an AVR micro. Should I rectify the voltages, then feed the DC voltage into the ADC, or is there a better way? The calculation time has to be pretty quick, so I'm guessing it would be unreasonable to sample the AC voltage and calculate...
  8. S

    3-Phase Earth-Neutral measurement

    How would I go about measuring the earth-neutral voltage? how would I configure the transformers, and what will be fed to the ADC? The non-linearity of the rectifier shouldn't be too much of a problem, as the voltages I'm measuring will not vary that much. Also, before the voltages are...
  9. S

    3-Phase Earth-Neutral measurement

    Hi, I need to measure the voltages and currents of a 5 wire 'Y' connected 3 phase system. Professional energy meters have turned out to be too expensive, so I'm thinking of just using stepdown transformers, rectifying the signal, then feeding it to an ADC. My problem is, how do I measure the...
  10. S

    Modbus code written in C for AVR chips

    modbus codevision thanks for the link, but I've only just started learning C in codevision and AVR are the first chips ive used. I had a read through the code, and I can see how it works but I'd still like to see an example for AVR. Does anyone know where to find some example code? even...
  11. S

    Modbus code written in C for AVR chips

    Hi, I'm working on a project at uni where I want to implement the Modbus protocol in Atmega16's. I'm pretty new to microcontrollers so I'm using codevision to write the code instead of assembler. I've got as far as getting a voltage reading from the ADC in a slave and transmitting it via...
  12. S

    Can I implement modbus using AVR microcontrollers?

    modbus avr I'm just wondering if its possible to implement modbus using AVR microcontrollers? does anyone know where i can get some good info on this stuff? It would be great to hear from anyone who has done this before. Thanks a lot, Sam
  13. S

    Help me use AVR ATmega16 for displaying decimal no on a LCD

    Re: AVR A/D question I'm already sort of familiar with C, so at the moment ive got codevision and AVR studio 4. Is there any example code around for doing this kind of thing? I cant seem to find any examples that are easy enough to understand. Thanks, Sam
  14. S

    Help me use AVR ATmega16 for displaying decimal no on a LCD

    AVR A/D question Hi, I need to measure voltages between about 200 and 260V and display them on an LCD. I will be using a voltage transducer that outputs a relative DC voltage between 0V and 5V. Im new to microcontrollers, and i have just bought an STK500 board and a couple of ATmega16's. Can...
  15. S

    RS-485 - Laptop interfacing

    laptop rs 485 So once ive got the required adapters and its all hooked up, how do i access the data from within the software? I read about some serial - USB converters that create a virtual com port. So how do i actually get the data from that port when writing a program in C++? will it be...
  16. S

    RS-485 - Laptop interfacing

    read 485 on you latop Hi, I need some basic info on how to get data from an RS-485 network into windows. Its for a monitoring network that we are putting together, and the computer being used will usually be a latop (no serial port). Can someone give me a basic explaination of how I should...
  17. S

    three phase voltage measurements

    If i was to use current transformers, would there be any possiblity of the transormer failing and causing a short or open circuit? It's absolutely essential that my circuit doesn't effect the power distrobution, even if any components fail.. Thanks, Sam
  18. S

    three phase voltage measurements

    Thanks heaps for all that. I should be able to get started now. It's good to know i can cut my number of measurements back to 7. I was thinking of using hall effect current transducers to measure the line currents, as i wont have break the circuit to take the measurements. Is there any...
  19. S

    three phase voltage measurements

    Actually dont worry about it, i figured it out. had to go back to high school maths.. is this method accurate and reliable though? can we count on the phase difference always being 120 degrees? even from a generator? thanks,
  20. S

    three phase voltage measurements

    Can you give me a quick example of calculating the phase to phase voltage using the cosine theorem? or a reference to good info on it? Will that method give an acurate phase to phase measurement even if the neutral-phase voltages differ by 10-20V? Also, I'm not sure I quite get what you mean...

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