Thermistor amplifier

  • Thread starter Thread starter Greg Denehy
  • Start date Start date
G

Greg Denehy

Hi there,
I am trying to measure a voltage using a picaxe chip from a simple
thermistor.
The picaxe measures from 0 to 5 volts, but in only about 16 steps, so I need
to amplify my thermistor so my range of interest to this voltage range.

The resistance will range from 15k (where I want the output from the
transisitor to be 0v) to 7k (Where I want the output to be 5V)

The supply voltage is 5V

Can someone show me the easy way to do this with an NPN transitor and a few
resistors. How to work out the resistor values would be appreciated too.

Thanks in advance for the help.

Greg
 
Greg Denehy said:
Hi there,
I am trying to measure a voltage using a picaxe chip from a simple
thermistor.
The picaxe measures from 0 to 5 volts, but in only about 16 steps, so I need
to amplify my thermistor so my range of interest to this voltage range.
Click to expand...

You would probably have better luck asking in sci.electronics.basics or
sci.electronics.design. You also might have better results using one of the
integrated temperature IC's such as the DS 1821.

Regards,
Bob Headrick
 
Hi there,
I am trying to measure a voltage using a picaxe chip from a simple
thermistor.
The picaxe measures from 0 to 5 volts, but in only about 16 steps, so I need
to amplify my thermistor so my range of interest to this voltage range.

The resistance will range from 15k (where I want the output from the
transisitor to be 0v) to 7k (Where I want the output to be 5V)

The supply voltage is 5V

Can someone show me the easy way to do this with an NPN transitor and a few
resistors. How to work out the resistor values would be appreciated too.

Thanks in advance for the help.

Greg
Click to expand...
I'd favor using a precision DC current probe like the Tek 6042 &
calculate the voltage from that.
 
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