R(THERMISTOR) CABLE 
; ri wmw__2_& THERMISTOR 
SB ESR S,=OFF-ON SWITCH 
Came R10 : =|.3 VOLTS 
1= 1000 
eee GR SAR Ro= 100 2 
Rg = 9 
Ee paula aus r = 23002 
Colette) eieeiR4 Ro © BS SOO CAL) 
; Rio= 3582.02 (10°C CAL) 
POSS RAS R,, = 3433.42(11°C CAL) 
Pyne pie Rip = 3292.39 (12°C CAL) 
Riz = 3157.80 (13°C CAL) 
paeiarie Bil Rig = 3029.6 2 (14°C CAL) 
Pons RIG Rig= 2907.02 (15°C CAL) 
Ryg= 2790.29 (16°C CAL) 
ae R\7= 2678.50 (17°C CAL) 
Riss 25 mela (1e2c CA) 
R92 2470.90 (19°C CAL) 
Se =I2POSITION SELECTOR 
SWITCH 
=e, + 
FIG. 5b 
Figure 5. Basic temperature bridge 
H1+H#H2, adjusts the span. Thus, for zero output at temperature 
OE ae with corresponding thermistor resistance R x? 
EM ear 
In practice, the batteries are replaced by a low resistance voltage 
divider network. The zero is adjusted by the resistor, R,. Also, 
the power dissipation of the thermistor in the medium in which it 
is to be used should be considered, i.e., the maximum current 
through the thermistor should be small enough so as to produce 
negligible self-heating. In the bridge circuit discussed above, 
the maximum allowable current was held to 50 microamperes, by 
the use of resistor, FR ,- Adjustment of F, does not alter the bal- 
ance point of the bridge but only the sensitivity or span. Since it 
