Star Tech Journal

STAR*TECH JOURNAL/JANUARY 1983
17
You can see that Vl and V2 both have . different voltage gains by just
changing resistor values. The output, V3, is now fed into A2.
Voltage gain for A2:
Av = -RF2 = 3.3K = -1
R3
3.3K
PRICE
CONVERSION
BREAKTHROUGH!
The Aud 1 output is the same in magnitude as V3, only inverted.
Voltage gain for A3:
A3 is a voltage follower covered in a following section. In this arrangement
the voltage gain is 1.
FOR ROWE
CIGARETTE
MACHINES
NON-INVERTING OP-AMP
RF
Rin
Vout
>-----
Vin
Vo= Vin (1 + RF )
Rin
AV=Vo =l+RF
-
Vin
Rin
Example 1: "Triple Hunt" 10 volt power supply
-
• Will vend up to $1.75 in
increments of 5¢.
~ - - +18v (unreg.)
+
I
06
C62
1000
25v
2N5190
• Accepts any combination of
nickels, dimes and quarters.
IN4001
CR12
I N4001
I
• Same mechanical
dependability using your
present totalizer. No
electronic components.
10K
+ CS3-
4700
25v
R80
10K
+
_
I
C53
100
25v
Vo= Vin (1 + RF )
Rin
= 5 (1 + lOK) = 5 (1 + 1) = 5 (2)
lOK
Vo= 10 volts
Example 2: If Rin = 4.7K, what would Vo be equal to then?
Vo= Vin (1 + RF )
Rin
= 5 ( 1 + lOK ) = 5 ( 1 + 2.1)
4.7K
= 5 (3.1)
= 15.5 Volts
Note: Both examples above ignore the . 7 volt drop between the base and
emitter of the transistor. If they were taken into account, Vo would be about
.7 volts lower.
• 4-minute installation on
location OR
• Send us your totalizer - we
will convert it ($5.00 service
charge).
LOTS OF:
1-10 ........ $49.95
11-50 ......... 48.00
51-100 ......... 4.6.00
101-1,000 ......... 44.00
Over 1,000 ......... 40.00
All orders shipped UPS/COD.
TELEPHONE:
516-928-6868
COIN UP-DATE
INDUSTRIES, INC.
14 Hulse Road
E. Setauket, NY 11733