Automatic level controlling circuit
AssigneeSanyo Electric Co., Ltd.
InventorKatsumi Imai
Life of this patent
Estimating the term…
Abstract
In an automatic level controlling circuit, an output from a full-wave rectifying circuit 12 is supplied to a first and a second time constant circuit. The first time constant circuit includes a first amplifier 22 and a capacitor 15. The second time constant circuit includes a second amplifier 23 and the capacitor 15. The first amplifier 22 operates when the output V1 from the full-wave rectifying circuit 12 is larger than a DC level VDC. In this configuration, the attack times when an input signal is switched from no signal into a middle level signal and when the input signal is switched from the middle signal into a high level signal can be set at optimum values, respectively.
Claims8
An automatic level controlling circuit for controlling an output from an amplifying circuit to a stable level when an input signal exceeding a prescribed level is received, comprising:
- first and second time constant circuits for setting an attack time for said automatic level controlling circuit;
- a comparing circuit for comparing an output from said first and said second time constant circuits or from said second time constant circuit alone with a reference voltage;
- and
- an amplifying circuit for controlling an output signal level according to a control voltage produced from said comparing circuit,
- wherein said first time constant circuit has a smaller time constant than that of said second time constant and is activated when an output of said amplifying circuit is larger than a predetermined level to vary the attack time.
An automatic level controlling circuit comprising:
- an amplifying circuit for amplifying an input signal to produce an amplified output;
- a full-wave rectifying circuit for full-wave rectifying the amplified output from said amplifying circuit;
- a first and a second amplifiers to which an output from said full-wave rectifying circuit is applied;
- a capacitor which is charged when an output from said first or said second amplifier is supplied;
- and
- a comparing circuit for comparing a detected voltage charged in said capacitor with a reference voltage to produce a control voltage for regulating an output level from said amplifying circuit,
- wherein said first amplifier has a smaller output impedance than that of said second amplifier and is operated according to an input signal level so that an attack time is variably set.
Dependencies are inferred from the claim text.