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Power-on sequencing using TL431 in comparator mode - TL431 as a
comparator. Delay timers. Power-on sequencers. TL431 without feedback can be
considered as an NPN or N-MOS device with high transconductance and precise 2.5V
turn-on voltage. Tube heads beware: the upper (+supply) pin on TL431 is cathode,
lower (-supply), anode.....it's another world. ….(design added 07/07) |
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Power-On Time Delay Relay - Here's a power-on time delay relay circuit
that takes advantage of the emitter/base breakdown voltage of an ordinary bi-polar
transistor. The reverse connected emitter/base junction of a 2N3904 transistor is
used as an 8 volt zener diode which creates a higher turn-on voltage for the
Darlington connected transistor pair. Most any bi-polar transistor may be used,
but the zener voltage will vary from about 6 to 9 volts depending on the
particular transistor used. Time delay is roughly 7 seconds using a 47K resistor
and 100uF capacitor and can be reduced by reducing the R or C values. Longer....
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Relay Delay - This circuit waits for a set time and then activates a
relay. With the cap that is in the schematic you will get about a 6 sec delay till
power on. You can change the cap in this circuit to 470uF for about a 20 sec
delay..... |
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Relays: Delayed Turn-On - This circuit is a delayed turn-on relay driver
and can produce time delays for up to several minutes with reasonable accuracy.
The 14001 (or 4001) CMOS gate here is configured as a simple digital inverter. Its
output is fed to the base of a regular 2N3906 (PNP) transistor, Q1, at the
junction …. [Tony van Roon's circuit] |
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Smooth Tone Clickless CW SideTone Generator - This circuit is about as
good as it gets for generating morse code tones. It may be used as a code practice
oscillator, a tone generator for a keyer, a sidetone oscillator for a CW
transmitter or an audio Modulated CW (MCW) generator for an FM transmitter or
repeater..... [G. Forrest Cook] |
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Soft-Start Circuit For Power Amps - Although the soft start circuit can
be added to any sized transformer, the winding resistance of 300VA and smaller
transformers is generally sufficient to prevent a massive surge current. Use of a
soft start circuit is definitely recommended for 500VA and larger
transformers..... [Rod Elliott (ESP)] |
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Switch on delay circuit - Schematic only, no circuit description
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time delay circuit - Schematic only, no circuit description |
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Time Delay Generator - Circuit Ideas for Designers Application Notes
Advanced Linear Devices, Inc.....[App Note] |
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Time Delay Relay - A time delay relay is a relay that stays on for a
certain amount of time once activated. This time delay relay is made up of a
simple adjustable timer circuit which controls the actual relay. The time is
adjustable from 0 to about 20 seconds with the parts specified. The current
capacity of the circuit is only limited by what kind of relay you decide to
use..... [Aaron Cake] |
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Time Delay Relay II - When activated by pressing a button, this time
delay relay will activate a load after a specified amount of time. This time
is adjustable to whatever you want simply by changing the value of a resistor
and/or capacitor. The current capacity of the circuit is only limited by what kind
of relay you decide to use.... [Author: jawaharlal@excite.com] |
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Time-delay relay reduces inrush current - 7-Mar-02 Issue of EDN A
transformer switching onto a line can sometimes cause a circuit breaker to trip or
a fuse to blow. This phenomenon occurs even if the transformer presents no
load, such as when the secondary is open. The problem arises because of the heavy
magnetizing inrush current in the transformer. The amplitude of the current
depends on the instant on the ac waveform at which the transformer become.....
[Design Idea by P Seshanna, Assumption University, Bangkok, Thailand] |
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Timer Circuits for Very Long Delays Using a CD4541B - Very Useful
Timers.....(design added 12/08) |
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Transistors offer overload delay - 16-Sep-04 Issue of EDN Although
an SMPS (switch-mode power supply] can protect itself against permanent short
circuits, it sometimes has problems when dealing with transient overloads.
Transient overloads are not short circuits but can push the power supply above its
nominal load value. This scenario occurs with typical loads such as printer
heads and small motors..... [Design Idea by Christophe Basso, On Semiconductor,
Toulouse, France] |
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Windshield Wiper Delay - The intermittent wiper circuit shown above
causes the auto's windshield wipers to wipe once every several seconds instead of
constantly wiping. The circuit may be added to older cars to provide the
intermittent function or it.....(electronic circuit added 08/08/08) |
