im building a pulse detection type circuit where the input is ac signal consisting of a series of pulses of different amplitudes. the output should be a dc type signal that maintains the peak voltage of the pulse until the next pulse comes along upon which it switches to the peak voltage of that pulse. i had in mind to use 2 half-wave rectifiers and logic gates to turn off and on each rectifier so that while 1 capacitor is charging the other is being read. im not too sure about where it is going but i was wondering if u had any possible ideas on how i could set up a circuit to do that. cheers.
Kevin Weddle
- Feb 23, 2004
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Here is the circuit. You don't need rectifier diodes. It will give you the positve cycle on demand and the negative cycle going positive on demand.
View attachment 36378
View attachment 36378
audioguru2
- Apr 6, 2004
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Hi Wingman,
Welcome to our forum.
Do you use an amplitude modulated carrier, like an AM radio?
To quickly store the amplitude of a pulse, then quickly change its voltage to the amplitude of the next pulse, you need a sample-and-hold circuit. It is made with a low-impedance buffer that charges or discharges a capacitor. It is activated by detecting the incoming pulse with a high gain amplifier. You can "read" the cap's voltage with a very high input resistance FET or FET-input opamp.
If your signal has pulses of both polarities, you can use an input transformer like in Kevin's circuit but use a center-tap as a voltage reference. Otherwise you need a full-wave bridge rectifier. His transistors perform like half-wave rectifiers.
Welcome to our forum.
Do you use an amplitude modulated carrier, like an AM radio?
To quickly store the amplitude of a pulse, then quickly change its voltage to the amplitude of the next pulse, you need a sample-and-hold circuit. It is made with a low-impedance buffer that charges or discharges a capacitor. It is activated by detecting the incoming pulse with a high gain amplifier. You can "read" the cap's voltage with a very high input resistance FET or FET-input opamp.
If your signal has pulses of both polarities, you can use an input transformer like in Kevin's circuit but use a center-tap as a voltage reference. Otherwise you need a full-wave bridge rectifier. His transistors perform like half-wave rectifiers.
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