When the input signal is ½ wave (+) then transistor 1 is on because the base gets bias (+) and transistor 2 is off because it gets bias (-) then, the current that occurs flows from the battery source (+) through the collector and emitter of transistor 1, to LS and back to GND. If the incoming signal is ½ wave input (-) then transistor 2 will be (on) because, the base gets bias (-) and transistor 1 is off because the base gets bias (+), so that the current will flow from GND (where (+) > GND > (-)) through the collector and emitter of transistor 2 and to (-) the battery source, and so on both transistors work alternately.
Complementary OCL Push Pull Amplifier
1. Tone Control
Divided into 2:
- Passive: that is, the high and low tone settings do not provide a strengthening effect.
- Active: this is the setting for high and low tones while simultaneously amplifying them.
2. Tone Control Section
- Filter
- Amplifier
- Feedback
3. Single Amplifier
Single Amplifier
Profit:
- Can provide sinus signal amplification with only 1 transistor
- Has a simple and easy circuit
Weakness:
- Have limited power
- Poor power efficiency (less current can be maximized)
- There is noise
Overcome Cross Defects in Push Pull Amplifiers
NPN transistor will be on if it gets base bias voltage (+) and PNP transistor will be on if it gets base bias voltage (-). When the signal is ½ wave (+), transistor 1 (T1) is on while transistor 2 (T2) is off, then there will be a current flow from the battery (+) through (T1) >> capacitor >> LS >> and back to the battery (-) this current also charges the capacitor (C) according to its polarity.
At ½ wave signal (-) T2 will be on and T1 off, then the current flows from C(+) through T2 >> LS >> and back to C (-). This condition makes C function as T2 power supply.
Definition of Cross Defect
In order for the transistors to be on, a bias voltage is needed. If both transistors are not given their own bias voltage, they will experience cross-fault characteristics.
By selecting the base emitter bias voltage we set a small quiescent current. So that defects originating from the curve curvature area can be avoided.
What is meant by cross defects is the occurrence of a shift at ½ wave (-) or (+) so that the reinforcement is defective and is known as a cross defect.
Push Pull Amplifier Has Cross Defect
How to Remove Cross Defects
Cross defects as in the image above can be eliminated by providing a base-emitter bias voltage to both amplifier transistors, namely by installing them in parallel with diodes made of the same material as the transistors (silicon/germanium) so that both transistors do not take part of the input signal (used as VBE) which causes cross defects.
Perfect Push Pull Booster