Application Notes
AN1003
2002 Teccor Electronics
Thyristor Product Catalog
AN1003 - 5
http://www.teccor.com
+1 972-580-7777
Figure AN1003.13
Precision Proportional Temperature Control
Several speed control and light dimming (phase) control circuits
have been presented that give details for a complete 120 V appli-
cation circuit but none for 240 V. Figure AN1003.14 and Figure
AN1003.15 show some standard phase control circuits for 240 V,
60 Hz/50 Hz operation along with 120 V values for comparison.
Even though there is very little difference, there are a few key
things that must be remembered. First, capacitors and triacs con-
nected across the 240 V line must be rated at 400 V. Secondly,
the potentiometer (variable resistor) value must change consider-
ably to obtain the proper timing or triggering for 180° in each half-
cycle.
Figure AN1003.14 shows a simple single-time-constant light dim-
mer (phase control) circuit, giving values for both 120 V and
240 V operation.
Figure AN1003.14
Single-time-constant Circuit for Incandescent Light
Dimming, Heat Control, and Motor Speed Control
The circuit shown in Figure AN1003.15 is a double-time-constant
circuit which has improved performance compared to the circuit
shown in Figure AN1003.14. This circuit uses an additional RC
network to extend the phase angle so that the triac can be trig-
gered at small conduction angles. The additional RC network
also minimizes any hysteresis effect explained and illustrated in
Figure AN1003.10 and
Figure AN1003.11.
Figure AN1003.15
Double-time-constant Circuit for Incandescent Light
Dimming, Heat Control, and Motor Speed Control
Load
120 V
(60 Hz)
R2
R6
R7
R3
R4
R8
D2
D1
D6
D3
R1
D5
TR5
T
T1
C1
Q1
D4
Q2
Triac
"Gain"
0
Ramp
Time
Cool
Hot
UJT Triggering Level
Pedestal
UJT Emitter Voltage
R1, R2 = 2.2 k, 2 W
R3 = 2.2 k, 1/2 W
R4 = Thermistor, approx. 5 k
at operating temperature
R5 = 10 k Potentiometer
R6 = 5 M Potentiometer
R7 = 100 k, 1/2 W
R8 = 1 k, 1/2 W
Q1 = 2N2646
Q2 = Q2010L5
T1 = Dale PT 10-101
or equivalent
D1-4 = 200 V Diode
D5 = 20 V Zener
D6 = 100 V Diode
C1 = 0.1
μ
F, 30 V
0.1 μF 200 V
0.1 μF 400 V
AC
Input
Voltage
120 V ac
60 Hz
240 V ac
50/60 Hz
12 A
3 A
250 k
500 k
Q2015L9
Q4004L4
100 μH
200 μH
R1
Q1
L1
C1, C3
R1
R2
3.3 k
C1
HT-32
AC
Input
C2
D1
Q1
L1
R3 *
100
C3 *
Load
Note: L1 and C1 form an
RFI filter that may be eliminated
* dv/dt snubber network
when required
0.1 μF
100 V
AC
Load
Current
0.1 μF 200 V
0.1 μF 400 V
0.1 μF 400 V
AC
Input
Voltage
120 V ac
60 Hz
240 V ac
50 Hz
240 V ac
60 Hz
8 A
6 A
6 A
250 k
500 k
500 k
Q2010L5
Q4008L4
Q4008L4
100 μH
200 μH
200 μH
R2
Q1
L1
C1, C2, C4
R2
R1
3.3 k
C1
HT-32
AC
Input
C2
D1
Q1
L1
R4 *
100
C4 *
Note: L1 and C1 form an
* dv/dt snubber network
when required
R3
0.1 μF
100 V
15 k
1/2 W
C3
Load
AC
Load
Current