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Sensors / Detectors: Frequency Monitors
Sensors / Detectors -- Main Page
Last Updated on:
Friday, October 16, 2009 03:42 AM |
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Links to electronic circuits, electronic schematics, designs for engineers, hobbyists,
students & inventors:
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Frequency Comparator Draws 8 µA - 03/03/97 EDN-Design Ideas / (Electronic
Circuit diagram added 03/03) |
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Frequency Comparator has Status Output - 12/26/02 EDN-Design Ideas /
(Electronic Circuit diagram added 03/03) The original application for the circuit
was to check the number of revolutions of an engine with only one LED as an
indicator... |
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Frequency Divider Adapts to I / O Conditions - 09/29/94 EDN-Design Ideas /
(Electronic Circuit diagram added 03/03) CanadaThe circuit in Figure 1 accepts an
input clock signal, such as from a crystal oscillator, and divides the frequency
according to the input divisor word. You can easily modify the basicdesign of this
versatile PLD-based ... |
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Frequency Window Comparator has hysteresis - 11/07/96 EDN-Design Ideas: The frequency
comparator in Figure 1 uses two VCOs. C1, R1+R2, and the voltage at pin 9 determine the
frequency of IC1 (900 Hz). C3, R5+R6, and the voltage at pin 9 determine the frequency of
IC2 (1580 Hz). If fIN is lower than 900 Hz, then the output P2 of phase-comparator 2 in
IC1 is high and drives.....(design idea added 5/02) |
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Make a simple PC based frequency meter - 04/29/99 EDN-Design Ideas: A simple, low
cost, and precision frequency meter uses only two pins of a pc parallel port (Figure 1).
The TTL-level periodic input signal with frequency fIN connects to the ACK pin of LPT1.
This input produces an IRQ7 hardware interrupt on every rising edge (Figure 2). The
software counts the number of IRQ7 interrupts in the time unit of.....(design idea added
11/05) |
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Frequency Window Comparator has hysteresis: 11/07/96 EDN-Design Ideas
/ (Electronic circuit added 5/02) The frequency comparator in Figure 1 uses two VCOs.
C1, R1+R2, and the voltage at pin 9 determine the frequency of IC1 (900 Hz). C3,
R5+R6, and the voltage at pin 9 determine the frequency of IC2 (1580 Hz). If fIN is
lower than 900 Hz, then the output P2 of phase-comparator 2 in IC1 is high and drives
the inhibit input of IC2 high via the R4-C2 lowpass filter. Consequently, the VCO in
IC2 turns off. fIN is therefore higher than IC2's frequency (0 Hz), so the output P2
of phase-comparator 2 in IC2 goes low, pulling the output low via the R8-C4 lowpass
filter. If fIN is higher than 900 Hz and lower than 1580 Hz, then the
output P2 of IC1 goes low and enables the VCO in IC2. IC2's frequency is higher than
fIN, so the P2 output of IC2 goes high. Simultaneously, Q1 removes the short circuit
across R2, and the frequency of the VCO in IC1 decreases to 870 Hz. The ratio of R2 to
R1+R2 determines the hysteresis of the first comparator.... |
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Make a simple PC based frequency meter: 04/29/99 EDN-Design Ideas / (added
11/05) A simple, low cost, and precision frequency meter uses only two pins of a pc
parallel port (Figure 1). The TTL-level periodic input signal with frequency fIN
connects to the ACK pin of LPT1. This input produces an IRQ7 hardware in- terrupt on
every rising edge (Figure 2). The software counts the number of IRQ7 interrupts in the
time unit of timebase T. If this timebase is 1 sec, the frequency of the input signal
equals the number of IRQ7 interrupts in 1 sec.... |
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