Tandy 1000 SL Technical Reference Manual page 308

S T 0
I N
1
I N 2
I N 3
I N 4
I N 5
I N
6
G N O
-
O U T 1
O U T 2
O U T
3
-
-
-
O U T
4
O U T 5
O U T 6
COM
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(Fig.208) Construction of d r i v e r I C , U 3
For t h e i n i t i a l 24msec of t h e s o l e n o i d a c t i v a t i o n , i t maintains t h e
HOD
o u t p u t a t H I G H l e v e l .
( 4 ) Overdrive c i r c u i t 1
The HOD o u t p u t s i g n a l
i s s u p p l i e d t o t h e o v e r d r i v e c i r c u i t 1 c o n s t r u c t e d
by t r a n s i s t o r s
42
(NPN) and Q1 (PNP) and it makes
Ql
t u r n on while t h e
HOD s i g n a l
i s
H I G H l e v e l . + 1 2 V power
i s
a p p l i e d t o t h e s o l e n o i d a t t h a t
t i m e t o execute t h e drawing-in a c t i o n of t h e s o l e n o i d s e c u r e l y .
A f t e r t h e o v e r d r i v e p e r i o d , t h e s o l e n o i d m a i n t a i n s i t s s i t u a t i o n with
+5V power through t h e diode C R 1 t o save t h e power.
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229
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