| ??? 06/25/04 11:54 Read: times |
#73155 - RE: Current & Voltage Monitor with RS232 Responding to: ???'s previous message |
Asok Sankar Rudra wrote:
------------------------------- To I am not expecting Nobel by asking this to FORUM that should we weigh
U7 74LS174 and U9 74LS08 + U10 CD4061+ U12 CD4066 versus 2x2051 Factor in also the software complications, compared to the analytic behaviour of the two logic parts. 3) Your current probe probably better known as tong tester in my part of the world and sure it is isolated from mains.But have you touched across the meter coil movement standing barefoot on ground? Unless the shunting impedance is very high, the voltage across the terminals will be negligible. 5) I note you prefer 1N4001 to 1N4007 although price and size are same but rating….. For a low voltage DC supply ? 6) You have written” If I were to use a Bridge rectifier I would require a center Tap transformer. “ Are you sure ?I think on the contrary. You're quite right. 8) “50 milli Volts Full Scale Deflection “: Thank you.Perhaps Andy can help in finding a more standard form than ‘50MVFS’. I offer mV FSD. The microcontroller measures the time required for the volt-age
on the capacitor to match the unknown voltage applied to the inverting input of the internal comparator (pin 13). The unknown voltage is a function of the measured time.”: I question is on the word ‘approximately’.What are values?Do you think it’s worth a thread? The technique is not unlike that employed in a dual-slope integrating A/D like the marvellous old ICL 7109, and with great care with components delivers very high precision, and good noise immunity. There is an old app note on the Intel site AFAIK. Steve |
