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V. Automatic Turn-Off After Short Time Delay
It is sometimes desirable for the EL lamp to turn off automatically after a few seconds of operation. Typically,
a mechanical switch pulls E’ low to initially turn on the device. When the switch is released, Cdelay keeps
the D355B operating for a short period before turning off. The following table shows typical delay on-
times.
VI. Automatic Turn-Off After Long Time Delay
Longer on-times can be achieved with the addition of an external transistor. Typically, a mechanical switch
pulls E’ low to initially turn on the device. When the switch is released, Cdelay keeps the D355B operating
for a period before turning off. The following table shows typical delay on-times using the following circuit
with smaller capacitor values.
Vbat
C
delay (µF)
1.5V
3.0V
5.0V
5
2.4 s
4.0 s
6.0 s
7
3.3 s
5.5 s
7.8 s
10
5.1 s
8.6 s
12.5 s
15
7.2 s
12.7 s
19.3 s
20
9.9 s
17.2 s
27.0 s
Vbat
C
delay (µF)
1.5V
3.0V
5.0V
1
9.5 s
13.0 s
15.6 s
2
17.8 s
24.0 s
29.0 s
3
26.5 s
36.0 s
42.0 s
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E’
CLF2
CLF1
V+
EL Lamp
L
Vbat
CLF
D355
1M
Ω
1.0
µF
Cdelay
1
2
3
4
8
7
6
5
GND
L-
VOUT
L+
E’
CLF2
CLF1
V+
EL Lamp
L
Vbat
CLF
D355
3.3M
Ω
470k
Ω
Vbat
1.0
µF
Cdelay
2N3904