negative voltage to adc

hi

i am designing a temperature measuring project in which i am using j ,k,r,s,e, t type thermocouples. j ,k,r,s provide me 0- 5 volts (after opamp stage), but e and t type thermocouples provide me negative voltage (when they measure from -200C to 0 Celcisus). if i amplify i ll get a negative value .then how will i feed this to adc.wht circuitry should i use to make this negative voltage on positive scale, i.e how to shift for example for t type

-200c to 400C i get ouput voltage -5.603mV to 20.872mV .i need to convert this to 0- 5 volts to feed it to adc.

i cant seperate j,k ,r ,s and e, t thermocouple inputs. so i need one general circuit so that if i apply any input(j,k,r,s,t,e) i should get the resulting ouput from 0-5 volts be the input negative or positive.

thanx

Take a look at the picture below ..
It is general purpose amplifier which can be used to amplify signals as well as level shifting ..
What you need to do is to use two-section 8-way (or whatever is required) rotary switch:
- section one - connected to the reference circuit can be used to shift levels from negative to positive, positive to "higher" positive etc ..
- section two - connected to the second amplifier between its (-) input - through adjustable resistors and GND (0V) will set the gain of the whole circuit to ensure 0-5V output ..

Regards,
IanP

ok good but what about the values of the resistors?????
thanks

Assuming that R1->∞, R4=R5=R6=R7 (for example 10kΩ):
Vout(IC1A) ≈ V(input)-V(between R1 and R2)

Gain of the second stage:
Gv = (R8+R9)/R9

Regards,
IanP