Metaxas & Sins solitaire, Manual

Page: 34 / 45

If we monitor the V+ point of the transistor circuit using an oscilloscope, we would notice this 0.1 Volts, 1.0 kHz signal. If we were to increase
the frequency to 10,000 Hz and up to 1.0 MegaHertz the speed of dynamic behaviour of the power supply becomes critical. Using a normal
I.C. regulator would result in the signal at V+ actually increasing in amplitude as the frequency increases so that at 1.0 MegaHertz the 1.0 Volt
sine wave is now over 1.0 Volt!
To fully understand this interaction between the ampli
fi er an power supply,it is necessary to understand how a voltage regulated power supply
works. A voltage regulated power supply is essentially a D.C. ampli fi er (not unlike a normal power ampli fi er) which instead of having an audio
signal at the input which is then ampli fi ed to become a larger audio signal at the output, has a fi xed D.C. voltage reference at the input which
is then ampli fi ed and becomes a larger DC voltage of at the output. The output impedance of the regulator, not unlike the output impedance
(or “Damping Factor’) of a power ampli fi er is less than one ohm at D.C. If we use a 2.0 Volt zener diode as our fi xed DC voltage reference at
the input of the D.C. ampli fi er which has a gain of 10, the resulting output voltage is 20 Volts D.C.The negative feedback loop of the ampli fi er
which fi xes the gain of 10 times the 2.0 Volt zener reference is very important because it maintains the output voltage irrespective of an
increase or decrease in the power supply voltage to the ampli fi er as long as there is a minimum voltage for the regulator circuit to operate (for
a 12 Volt regulator, the minimum voltage is 15 Volts).