8 - 3
m e a s u r i n g
Di r e c t C u r r e n t ( D C ) V o l t a g e
The o s c i l l o s c o p e ' s v e r t i c a l a m p l i f i c a t i o n I s proven by a d i r e c t c u r r e n t a m p l i f i e r c i r c u i t
c h a r a c t e r i z e d by e x c e l l e n t s t a b i 1 i t y . By s w i t c h i n g t h e AC-GND-DC c o n t r o l t o t h e DC
s e t t i n g , d i r e c t c u r r e n t v o l t a g e may be measured.
1) Apply the s i g n a l to the INPUT t e r m i n a l . Use the VOLTS/DIV and SWEEP TIME/DIV c o n t r o l s
to d i s p l a y the waveform a t an e a s y - t o - s e e s i z e . A d j u s t the TRIGGER LEVEL c o n t r o l a s
n e c e s s a r y .
2) Set the T. MODE c o n t r o l to AUTO. S e t the AC-GND-DC c o n t r o l to GND. The t r a c e l i n e i s
d i s p l a y e d on t h e CRT. T h i s t r a c e 1 i n e r e p r e s e n t s t h e ground p o t e n t i a l . Use t h e
^ P O S I T I O N c o n t r o l t o b r i n g t h e t r a c e 1 i n e i n c o n t a c t w i t h one o f t h e h o r i z o n t a l
g r a d u a t i o n l i n e s . I t i s n o r m a l l y l i n e d up on the OX g r a d u a t i o n l i n e i f t h e s i g n a l i s
p o s i t i v e . Or, i t i s 1 i n e d up on t h e
100%
1 i n e i f t h e s i g n a l i s n e g a t i v e . Once
1 i n e d up, t h e t r a c e p o s i t i o n becomes t h e r e f e r e n c e p o t e n t i a l , so do n o t t o u c h t h e
^ P O S I T I O N c o n t r o l d u r i n g measurement p r o c e s s e s .
3)
S e t the AC-GND-DC c o n t r o l to DC. The s i g n a l i s d i s p l a y e d on t h e CRT w i t h the d i r e c t
c u r r e n t components i n t a c t .
I f e i t h e r the VOLTS/DIV or r e f e r e n c e p o t e n t i a l s e t t i n g i s i n a p p r o p r i a t e , the waveform
may d i s a p p e a r from the d i s p l a y s c r e e n . Make sure the s e t t i n g s a r e c o r r e c t .
4 ) Measure the p o t e n t i a l i n the e q u i v a l e n t procedure to measuring the v o l t a g e between two
p o i n t s . T h e p o t e n t i a l s i g n i s p l u s i f above t h e r e f e r e n c e o r minus i f below t h e
r e f e r e n c e .
Ground potential adjusted by
I POSITION (reference line)
F i g u r e
12-1
DC Voltage Measurement
37
Measuring point adjusted to the center
vertical scale by ^ • POSITION
