LM4702 Plus Lateral MOSFET 120 Watt Amplifier:
   
   
   
   
   
   
 

Driver Schematic -- for clarity the connection from Sink1 to the collector of Q1 is not shown.

  

 

Output Schematic

  

Driver Board Under Test

  

Modifying the Bias Stage for Single Vbe Multiplier

To bias the output devices, the driver board can be adapted to

1. Use two transistors in a totem-configuration, or
2. Use one transistor as a conventional Vbe Multiplier, or
3. Use no transistors at all if Lateral MOSFETs are used as output devices

Option 2 is illustrated below.  Placing a jumper between the Collector and Emitter positions for  Transistors Q2 and Q3, Resistors R12 and R18 allows use of

 
   

1 Borbely, Erno "A 60W MOSFET Power Amplifier" The Audio Amateur 2/82 pp 7-15. (See correction in 3/82 as well)

2 Borbely, Erno "Two 100W MOSFET Power Amplifiers" The Audio Amateur 1/84 pp 7-18 and The Audio Amateur 2/84 pp 13-24.