Signal Scaling using analog circuit

[narithota]

hi

I have to convert the 0v to 5v signal to 0.8v to 3.6v using analog circuit.Input 0v means output should be 0.8V & Input 5v means output should be 3.6V.How to do the scaling with out using micro controller.

Regards
nari

 

[keith1200rs]

See here:

https://www.edaboard.com/threads/189649/

Keith.

 

[WimRFP]

When source impedance is relatively low and load impedance is relatively high, you can use a voltage divider with a division ratio of 1.786 ( 5/(3.6-0.8 ) ), for example 5.6 kOhms (to ground) and 4.4 kOhms (from the source). This provides the division ratio.

Next step is to add the offset (as you require 0.8V output with 0V input). The offset you can create by lifting the ground connection of the divider to 1.82V (0.8*(1/0.44).

If you have a stable source (for example 5V), you can convert the 1.82V source with the 5.6 kOhm resistor to a new voltage divider fed from 5V. This two resistors should provide 5.6 kOhms in parallel.

The result will be three resistors. For example: 15.38 kOhms to the 5V reference, 8.80 kOhms to ground, 4.4 kOhms to output (0...5V). all other terminals go the the input (0.8..3.6V).



You may have to include output/input impedances of source/load.

 

[enjunear]

Try this out. Initially, you set up the top voltage divider to give you 3.6V when the PNP transistor is turned off (Vin @ 5V). When your input signal goes low (Vin @ 0V), the transistor pulls the output node closer to ground (0.8V, ideally).

You'll need to expirement with the values, but this should give you a place to start.