(C) Mr.Linker
Attachment for measuring the temperature
DMMs
Easy attachment containing six
resistor allows the use of a digital voltmeter to measure the
temperature with a resolution of 0.1 degrees and
thermal inertia of 10 ... 15 seconds. When
such a speed it can be applied
and to measure body temperature. In the measuring device to
make changes not required, and production consoles available
for beginners and amateurs.
As the sensor is applied Semiconductor thermistor ST3-19 with
a nominal resistance of 10K at T = 20 degrees.
Together with an additional resistor R3
He forms one half of the measuring
bridge. Second half - a voltage divider of resistors R4 and R5,
the last calibration sets the initial
the output voltage. Multimeter is used in the measurement mode
constant voltage on the 200
or 2000 mV. Appropriate choice
resistor R2 change
sensitivity of the measuring bridge.
Immediately before measuring the temperature variable
resistor R1 sets the supply voltage measuring circuit equal to
that at MDM performed the initial calibration.
Include the prefix for the reference temperature measured by
push-button switch SB1, and the translation of the measurement
mode, setting mode voltage - switch SB2. Calibration consoles
produced in two points:
TM TK1 = +0.707 (T2-T1) / 2
Tk2 = Tm-0.707 (T2-T1) / 2
where: TM = (T1 + T2) / 2
T1 - the beginning of the temperature range
T2 - The End of the temperature range
During the initial calibration
with a fresh power cell resistance of the variable resistor R1
sets the maximum, to the extent of loss capacitance and voltage
reduction element it was possible to maintain tension on the
bridge unchanged.
Adjustment trimmer potentiometers
R2 and R5 achieve compliance in three
Signs reading digital display
meter values of the temperature of the thermistor TK1 and
TR2-controlled accurate thermometer. In its absence can be used
for medical temperature control in predelazh its scale and
stable temperature of melting ice - 0 degrees.
(C) radio, N3, 1999.
B. Ratnovsky
Samara
Click to view <V> scheme, in view ss +4 - screen recording;
edit, break - to exit the viewer.
PS: Now about copyright'ov,
arranged in my articles.
So, I'm not in any way do not pretend
the title of the author of these developments, and
this case only to emphasize that
I dug up this stuff and gave dany
it to you. I think that the authors of these materials, and our
dear readers will understand my actions and will not be more to
claim.
Sincerely Mr.Linker
28.04.99 IS-EDITOR
