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Converters: Period to Voltage
Converters -- Main Page
Last Updated on:
Friday, July 18, 2008 11:32 AM
| Circuits Designed by Dave Johnson, P.E. : |
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PULSE PERIOD TO VOLTAGE CONVERTER
This is a test circuit converts a square wave input signal into a voltage. But, the voltage produced is proportional to the time between edges (period) of the signal, not the frequency. The
range is from 100uS to to 10mS, which produces a voltage from 100mV to 10 volts. Other scale factors are also possible. The circuit is powered from single 15v supply and uses inexpensive parts.
It is great when a signal's period instead of its frequency needs to be monitored.
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| 555 Makes handy Voltage to time Converter: 02/01/01 EDN-Design Ideas / (added 05/03) The circuit in Figure 1 is a simple, low-cost voltage-to-time converter using the ubiquitous 555 timer chip. You can use
the IC's monostable multivibrator as a voltage-to-time converter by connecting the analog-voltage input to the charging resistor, R, instead of connecting R to VCC. With this modification, the
timer chip's output-timing cycle, tP, is proportional to the input voltage, VIN. When you apply an input voltage, the voltage across capacitor C charges exponentially according to the formula
VC=VIN(1–et/RC), where RC is the time constant of the circuit, with C in farads and R in ohms. During one time constant, the voltage across the capacitor changes by approximately 63% of VIN.
The output timing of the monostable multivibrator is tP=1.1 RC. By keeping RC constant with fixed R and C values and varying the input voltage, VIN, you obtain variable output timing. The
output pulse width in this circuit is inversely proportional to the input voltage.... |
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Circuit Converts Pulse Width
to Voltage #2: 10/28/99 EDN-Design Ideas / (added 1/04) -- PDF contains multiple circuits - scroll to find this circuit. --- The circuit is optimized for a positive-going pulse width of1
to2 msec, repeating at intervals of approximately17 msec. The output produces a voltage of0.95V for a1-msec pulse to2.25V for a2-msec pulse. |
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Circuit Converts Pulse Width
to Voltage: 10/25/01 EDN-Design Ideas / (added 1/04) The circuit converts pulse information to a clean dc voltage by the end of a single incoming pulse. In another technique, an RC filter
can convert a PWM signal to an averaged dc voltage, but this method is slow in responding. Converting low-duty-cycle pulse information is slower yet. |
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