
AN1003
Application Notes
http://www.teccor.com
+1 972-580-7777 
AN1003 - 2
2002 Teccor Electronics
Thyristor Product Catalog
Figure AN1003.3
Half-Wave Phase Control (Sinusoidal)
Figure AN1003.4
Symmetrical Full-Wave Phase Control (Sinusoidal)
Figure AN1003.3 and Figure AN1003.4 also show the relative 
power curve for constant impedance loads such as heaters. 
Because the relative impedance of incandescent lamps and 
motors change with applied voltage, they do not follow this curve 
precisely. To use the curves, find the full-wave rated power of the 
load, and then multiply by the ratio associated with the specific 
phase angle. Thus, a 180° conduction angle in a half-wave circuit 
provides 0.5 x full-wave conduction power.
In a full-wave circuit, a conduction angle of 150° provides 97% 
full power while a conduction angle of 30° provides only 3% of full 
power control. Therefore, it is usually pointless to obtain conduc-
tion angles less than 30° or greater than 150°
.
Figure AN1003.5 and Figure AN1003.6 give convenient direct 
output voltage readings for 115 V/230 V input voltage. These 
curves also apply to current in a resistive circuit.
Figure AN1003.5
Output Voltage of Half-wave Phase
Figure AN1003.6
Output Voltage of Full-wave Phase Control
Peak Voltage
RMS
AVG
Power
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0 
20 
40 
60 
80 100 120 140 160 180 
Conduction Angle (
θ
)
N
a
HALF WAVE
θ
Peak Voltage
RMS
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0 
20 
40 
60 
Conduction Angle (
θ
)
80 100 120 140 160 180 
N
a
FULL WAVE
Power
AVG
θ
θ
Peak Voltage
180
160
140
120
100
80
60
40
20
00 
20 
40 
60 
Conduction Angle (
θ)
80 100 120 140 160 180 
RMS
AVG
O
360
320
280
240
200
160
120
80
40
0
Input
Voltage
230 V 115 V
HALF WAVE
θ
Peak Voltage
RMS
0 
20 
40 
60 
80 100 120 140 160 180 
Conduction Angle (
θ
)
AVG
O
360
320
280
240
200
160
120
80
40
0
Input
Voltage
230 V 115 V
180
160
140
120
100
80
60
40
20
0
FULL WAVE
θ
θ