The Class-A Amplifier Site
This page was last updated on 7 May 2001
D C Voltages
The following tables of dc voltages are provided to assist in initial testing and any fault-finding that may be required. They have been prepared from simulations of the 1969 and 1996 versions. The 1969 version was simulated with a supply rail voltage of 27V and a quiescent current of 1.2A and the 1996 version with +/-22V supply rails and a quiescent current of 2A.
The last three columns in the tables have been included to allow calculation of nodal dc voltages at other supply rail voltages. Vs is the supply rail voltage (the value of a single rail for dual-rail supplies), Vbe is the base-emitter potential for a transistor (typically 0.7V) and Iq is the quiescent current.
1969 Version
|
Device |
Emitter |
Base |
Collector |
Emitter |
Base |
Collector |
|
Tr1 |
0V |
0.7V |
13.5V |
0 |
Vbe |
Vs / 2 |
|
Tr2 |
13.5V |
14.2V |
27.0V |
Vs / 2 |
(Vs / 2) + Vbe |
Vs |
|
Tr3 |
0.7V |
1.4V |
14.3V |
Vbe |
2.Vbe |
(Vs / 2) + Vbe |
|
Tr4 |
12.9V |
12.3V |
1.4V |
(Vs / 2) - Vbe |
(Vs / 2) - 2.Vbe |
2.Vbe |
1996 Version
|
Device |
Emitter |
Base |
Collector |
Emitter |
Base |
Collector |
|
Tr1 |
-22V |
-21.3V |
0V |
-Vs |
-Vs + Vbe |
0 |
|
Tr2 |
0V |
0.7V |
21.3V |
0 |
Vbe |
Vs - (Iq / 3) |
|
Tr3 |
-21.3V |
-20.5V |
0.7V |
-Vs + Vbe |
-Vs + 2.Vbe |
Vbe |
|
Tr4 |
0.7V |
0.1V |
-20.5V |
Vbe |
0.1 |
-Vs + 2.Vbe |
|
Tr5 |
21.3V |
20.7V |
0.7V |
Vs - (Iq / 3) |
Vs - (Iq / 3) - Vbe |
Vbe |
HISTORY: Page created 07/05/2001