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150v to 300v voltage indicator
Hi, as a newbie hobbyist to electronics i am having difficulty working out how to adapt a bargraph circuit using LM3194 (see attached image) the circuit is for measuring 400v. i need to make it measure the entire range from 150v to 300v. could someone shine some light on this for me please.
or is the wrong type of chip to use ?
thanks in advance
Sarah.
I would suggest using some resistors to drop the 300V down to a reasonable working voltage, say under 10 volts, depending on the input range of the LM3194 (Much like the two 470K and 12K resistors). Then using one op-amp to give you the proper gain so that varying from 150V to 300V gives you a voltage swing on the output of the op-amp the same size as the maximum input to the LM3194. Then using a second op-amp shift the voltage down so 150V will give you 0V out and 300V will give the max input of the LM3194.
thank you for the reply, i found a little program that works out the values for voltage dividers, and by using just 2 resistors i can get the 5v max required for the entire range 150v-300v :-)
I just need to find the time to try it :-)