re adc card for computer in article qi e b e lll winken llnl gov you say i would like to digitize the output of a squid magnetometer range v to v and do digital signal processing in a computer say a macintosh ii or a pc i would like a good bit adc with good linearity and a high conversion speed at least khz preferably khz other concerns must i use an adc external to my computer to avoid digital noise feedback into my sensitive squid electronics might be a good idea the resolution you requested is about mv in order to get what you ve paid for noise level better be lower than that it is kind of hard to do it in a noisy box like you can expect inside a pc before you pay for a pc card test it out by sampling a low distortion sine wave i think there is a sine wave on a cd digital domain there are possibly other low thd sources run the digitized waveform through a fft transform and take alook at the noise floor on the spectrum that s should give you a good indication of the design that s what i am doing to test a data acquistion system i have designed i got the idea from maxim data sheet if you can live with bit resolution i would recommend looking at the max from maxim it is a high speed khz complete sampling a d with dsp interface the input range is v and it uses a serial interface which can easily be optically isolated from the computer to elinimate a major noise source the analog design guide i got from them shows a db noise level they claim a db max typ thd looks pretty good for the pieces a evaluation kit is available might want to give these nice folks a call or fax and ext for application assistance this assumes that you can build your own das and write your own software hey you can get the max as a free sample just by calling the i would appreciate discussion of your personal experience with a mac or pc based adc system i would recommend you to find out the resolution that can be gotten out of your system by looking at the noise level otherwise you might be throwing out your money charles cunningham cec imager llnl gov k c lee elec eng grad student i have no connection with maxim except i do in general recommend companies that give samples to students to others i feel they deserve that for being nice to me
