_____________________________________________________________________ Special Amplifiers
ER1 = (voltage at point A) - (El)
ER1 = (+10 V) - (+3 V)
ER1 = +7 V
Compute the current through R1 (IR1):
ER1
IR1 =
R1
+7V
=
IR1
kΩ
= + 7 mA
IR1
IR1 = IR3
Since:
IR3 = + 7 mA
Then:
Compute the voltage developed by R3 (ER3):
ER3 = R3 x IR3
ER3 = (5 kΩ) x ( +7 mA)
ER3 = +35 V
Add this voltage to the voltage at point A to compute the output voltage (EOUT):
EOUT = (ER3) + (voltage at point A)
EOUT = (+35 V) + (+10 V)
BOUT = +45 V
This was the output desired, so the circuit works as a difference amplifier.
MAGNETIC AMPLIFIERS
7-97. You have seen various ways that electron tubes and transistors can be used to
amplify signals. There is another type of amplifier in use, the MAGNETIC AMPLIFIER
(sometimes called the MAG AMP).
7-98. The magnetic amplifier has certain advantages over other types of amplifiers.
These advantages include:
High efficiency (up to 90 percent).
Reliability (long life, freedom from maintenance, and reduction of spare parts
inventory).
23 June 2005
TC 9-62
7-35
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