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CMOS Schmitt Trigger IC Makes VCO
By changing the supply voltage fed to a classic 4584 Schmitt trigger type
oscillator, the oscillator frequency can be changed over a range of 50:1. A
74HCU04 inverter is used at the output of the 4584 to maintain a constant TTL logic
level signal...
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Low Power Oscillators
This page has two unusual two-transistor oscillators. I set the component
values for a low frequency application. Both circuits draw only about 1
microamp of current. (added 12/04)
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Micropower CMOS Oscillator, Draws
Only 0.5ua
If truly low power oscillators interest you, this circuit draws a mere 2 microwatts
(500nA) from a 6v battery. It uses a very inexpensive C-MOS IC to produce a
frequency of 2Hz. However, by changing the component values you can push it to
300Hz. The circuit draws much less current than traditional C-MOS oscillators using
a Schmitt trigger inverter. It also produces fast leading edges. However, if you
need more drive current, a C-MOS buffer should be included. Published in EDN,
September 2, 1993
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Oscillator Draws 2 Nanoamps
This page shows two low frequency oscillators that draw ultra low current....
[Designed by David A. Johnson]
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Precision Ultra Lower Power
Oscillator
This circuit works much like the classic 555 timer, but draws only about 1.5
microamps from a 3 volt battery. It is highly stable under varying temperature and
supply voltages....
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Three Volt Low Battery Voltage
Flasher
This circuit is designed to monitor two alkaline cells (3v) that form the battery
often used in portable electronic equipment. It use an inexpensive IC from
Panasonic that is connected to an efficient LED flashing circuit. When the
battery voltage drops below a certain point the circuit flashes the LED. In
the off state the circuit draws only 1uA, while in the active flashing state it
draws 20uA. Published in EDN, Jan 2, 1997
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Ultra Low Current Oscillator
Here is a challenge. Design an astable oscillator which draws only a few
nanoamps of current from a +3v supply. I gave this some thought and came up
with the circuit below. I used some pretty standard parts except for three
surface mounted 1000M resistors I had on hand. The oscillator frequency
measured a low 1Hz frequency and the average current was a very low 3 nanoamps.
If I had some higher resistors values handy, I think I could have gotten the current
down below one nanoamp....
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Ultra Low Power Astable
Multivibrator
Taking advantage of some new voltage comparators, this circuit can produce a nice
square wave signal while drawing only 1.6 microamps. With the inclusion of a
diode, the circuit can also produce short pulses instead of a square wave signal.
(added 12/04)
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