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Simple audio limiter circuit

Return to Homebrew Radios and Equipment. Ads are not permitted. I use an mp3 player on random as the source, and some of my mp3s are at different levels. I'd like to add a little bit of compression to maintain a more even volume on a radio, and be able to keep it from overmodulating in the process. Any thoughts? Solid state limiters are easier to build, but not always that easy to make sound good.


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Simple audio limiter circuit

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WATCH RELATED VIDEO: Audio Limiter and Squelch

TRUE AGC AUDIO LIMITER


Sept- L. The invention relates to circuit arrangements for producingelectric waves in response to desired acoustic waves, and it particularly pertains. Although the basic concept of limiting the amplitude of an audio frequency electrical wave useful for example in preventing overmodulation of a modulated R. Furthermore, the known arrangements are relatively complex and are'prone to allow microphonic disturbances to be set up due to the complexity of the circuits.

To overcome the latter disadvan tage, even more complex circu try hasbeen suggested, which of course entails considerable exn e in construction. I lt is an object of the invention to.

It is another object of the invention to provide a circuit arrangement preventing overmodulation ofthe carrier wave by maintaining a constant audio input volume level to the modulating c cuit of a radio transmitter. It is still another ob ect of provide a modulation circuit, arrangement contributing negligible distortion to the.

H wave while permitting the utilization, of an acoustical input volume varying over a wide range oi'intens ties. It is a. I Theseand further objects of i the invent on w ll appear as the specification progresses. In accordance with the invention there is provided acircuit arrangementfor coupling aca-rbon microphone to the amplifying stages of a utility device, for example a public address-system or especially those employedv the. The invention will be described with reference to the accompanying drawing forming a part of the specification and in which: 7.

While the basic principles of the carbon microphone are well known to the artisan, a concise explanation of the operation of the same will not be amiss at this point inasmuch as the invention is based thereon.

Carbon microphones usually comprise one or two members, termed buttons by those familiar with the 'art, having small carbon granules lightly held therein so that they may be compressed and released by actuation of acoustical waves impinging on a collector which is usually provided in the form of a flat mechanical diaphragm.

Each button is'connected in series with a source of direct potential and an output device which, in nearly every'practical case, is a voltage step-up transformer. As the acoustical waves efi'ect compression and release.

Since the current remains substantially constant, the potential across the button varies proportionally in accordance with ohms law to, produce an electric wave of audio frequency whichis applied to any tion as a control of the amplitudelevel of the first voltage. The above mentioned audio frequency voltage is developed by actuation ofthe potential, shown here as a battery 20, a direct;.

If the direct current is substantially constant an audio frequency voltage proportional to the acoustic energy incident to the microphone will appear across the microphone terminals. If, however, the direct current in this circuit is varied proportionally to the amplitude level of the derived audio frequency voltage the amplitude level can be maintained at any desired proportionate value.

The present embodiment of the invention contemplates maintaining the audio frequency voltage level constant by varying the direct current inversely proportional to the amplitude level of the derived voltage by varying the resistance component existing between the cathode 22 and the anode 24 of tube 2.

This is accomplished in an actual circuit by connecting the remaining button IS in series with the source of direct potential, shown here as battery 29, and the primary Winding of a transformer 3. The audio frequency voltage induced in the secondary winding 32 of transformer 3 is applied via a coupling capacitor 33 to a load resistor A direct potential proportional to the alternating voltage is obtained by means of a diode rectifier 35 connected across resistor 34 and is applied via a resistor 38 connected to anode 3?

The, direct potential appearing on capacitor 39 is applied through the intermediary of a decoupling network comprising a resistor 44 and a capacitor 45, eliminating to an adequate extent any alternating voltage on control grid 23 of triode 2. The direct potential applied to the grid 23 of tube 2 determines the current passing through the tube, which is the same current that fiows through microphone button l3.

Since there is provided a means of making the microphone current diminish as the input signal increases and vice versa, theaction tends to make the output level remain constant regardless of wide variations in the input level. Any microphonics will be effectively filtered out by capacitor l9.

Since the electrical wave derived in response to the acoustic wave impressed on the diaphragm ofmicrophone H is confined to a circuit comprising the primary l6 of transformer El and capacitor l9, any distortion or microphonics must originate in capacitor l9, transformer IT, or button 3 of microphone II. If capacitor I9 is madesufficiently large, it is very unlikely that it will contribute any distortion and it cannot'possibly contribute any microphonics.

Transformer likewise cannot contribute microphonics and the distortion contributed may be made as low as is consistent with the size and cost of the transformer.

Microphone II is then the only appreciable source of noise and distortion and by careful selection and construction thereof distortion from this source can be held to negligible value. The audio frequency voltage derived across secondary winding l8 of transformer i? The audio frequency voltage appearing in the circuit will traverse the. From the high side of winding 44 a coupling capacitor 46 and a coupling resistor 48 apply the audio frequency voltage to the control grid 52 of an amplifier tube The audio frequency voltageis amplified by tube and the amplified voltage appears across a load resistor By 'means of a coupling capacitor '55 the amplified audio'voltage is applied to a diode rectifier and diode load resistor 6.

A resistor 62 and a capacitor 63 are connected in series across load resistor 6 ,a negative voltage appears across capacitor 63 and is transferred by way of a decouplingresistor 64 and'a decouplingcapacitor 65 to the grid electrode 23 of limiter tube 2. The decoupling network comprising resistor 64 and 65 prevent, to an adequate extent, any alternating voltage from reaching the grid 23 of tube 2.

The direct voltage applied to the grid of tube 2 determines the current passing through the tube, which is the'same current flowing through microphone 4. Since there is provided a means of making the microphone current diminish as the input signal increases and vice versa, this. Any wave of microphonic origin Will be effectively filtered out by capacitor l9. Since the electric wave derived in response to the acoustic wave impressed on the diaphragm of microphone 4 is confined to a circuit comprising the primary 42 of transformer 43 and capacitor l9 any distortion or micro phonics must originate in capacitor l9, transformer 43 or microphone.

As previously stated a sufficiently large capacitor I9, together with carefully selected and constructed transformer 43 and microphone 4 , serve to hold'distortion from this source to negligible value. The audio frequency voltage derived across secondary winding 44 of transformer 43 may be applied directly to the modulation stage of the radio transmitter without further amplification thus eliminating the possibility of any microphonics or distortion arising in subsequent amplifier stages.

As shown in Fig. Referring to Fig. Where the components of Fig. In this arrangement the amplifier stage has been eliminated and the control voltage'developed across resistor 48 is rectified by means of a diode 10, having its cathode H connected to the junction of capacitor 46 and resistor 48, and.

Any form of rectifier may be used such as a crystal or copper oxide rectifier if desired. Also the physical size of the arrangement may be reduced by employing a diode-triode type tube for control tube 2 and diode T0, or a twin triode tube. Vacuum tube 78 is an audio amplifier operating in the. It should be noted that in the arrangements shown, couplin capacitor 4'6 '33 in Fig.

With the circuits shown, a satisfactory rate of 3 db per octave can be readily obtained. The circuit arrangements shown are obviously advantageous for use with public address systems, 'in which systems the pre-emphasis characteristic is often also desirable. It is also contemplated that the principles of the inventioumay be put into use with electrical devices requiring the smallest of available components, such as hearing-aid devices, radio transmitters of the so-calledhandy-talky type, and the like, and incorporating either miniature electron discharge devices or multi-electrode crystal devices such as transistors, or combinations of these devices, with results equal to those obtained with components expressly described, It is believed that the advantages incurred by the use of the invention as applied to hearing-aids are too obvious to discuss in detail.

While the invention has been described with reference to several express embodiments thereof, it is understood that many obvious modifica tions. An electronic circuit arrangement.

An electronic circuit arrangement for main-r taining a substantially constant electric output amplitude level from an acoustical-electrical conversion device in response to a varying acoustic input level, comprising said acousticalelectrical conversion device, an electron discharge device defining a space charge path and a source of direct potential connected in series, means to produce a direct control potential pro-- portional to the amplitude of said input level, and means-to apply said control potential to said electron discharge device in direct proportion to the amplitude of said input level and in such direction as to vary the.

An electronic circuit arrangement for maintaining the electric output level of a. An electronic circuit arrangementfor maintaining a substantially constant electrical outputlevel from a. An electronic circuit arrangement for maintaining a substantially constant electric level from carbon-button microphone having a varying level of acoustic energy applied thereto, comprising said microphone, a microphone transformer having primary and secondary windings, an electric device having first, second and third electrodes spaced apart from each other, said second electrode being a control electrode, means to couple the electric circuit of said microphone, the primary winding of said transformer, and the circuit path between said first and said third electrodes of said electric device in series with a source of direct potential, a rectifier device, means coupling the secondary winding of said transformer to the input circuit of said rectifier device, and means to couple the output of said rectifier device to said second electrode of said electric device to bias said control elec-- trode with respect to said first electrode.

An electronic circuit arrangement comprising a carbon-button microphone, a microphone transformer, an electron discharge device having cathode, control and anode electrodes, and. An electronic circuit arrangement comprising a double button carbon type microphone, first and second microphone transformers each having primary and secondary windings, an electron discharge device having cathode, control and anode electrodes, means to apply a direct potential in series circuit with one button of said microphone, the primary winding of said first microphone transformer and the cathode-anode electrode circuit of said electron discharge device, means to apply a direct potential in series circuit with the other button of said microphone and the primary winding of said second microphone transformer, a rectifier element, means to couple said rectifier element to the secondary winding of said second microphone transformer, and means coupling said rectifier element between a point of reference potential of said series circuits and the control electrode of said electron discharge device.

An electronic circuit arrangement comprising a carbon-button microphone, a microphone transformer, a first electron discharge device having cathode, control and anode electrodes, and means to apply a direct potential in series circuit with said carbon-button microphone, the input winding of said microphone transformer and the cathode-anode electrode circuit of said first electron discharge device, a second electron discharge device having a cathode, a grid and an anode, means coupling the output winding of said microphone transformer between the grid and cathode of said second discharge device, and means coupling the anode-cathode circuit of said second electron discharge device between a point of reference potential of said series circuit and the control electrode of said first electron discharge device.

An electronic circuit arrangement comprising a carbon-button microphone, a microphone transformer, an electron discharge device having cathode, control and anode electrodes, and means to apply a direct potential in series circuit with said carbon-button microphone, the input winding of said microphone transformer and the cathode-anode electrode circuit of said electron discharge device, a rectifier element, means coupling the output winding of said micro phone transformer to said rectifier element, and means coupling said rectifier element between a point of reference potential of said series circuit and the control electrode of said electron discharge device, said means comprising a filter section.

An electronic circuit arrangement comprising a carbon-button microphone, a microphone load device, an electron discharge device having cathode, control and anode electrodes, and means to apply a direct potential in series circuit with said carbon-button microphone, said microphone load device and the cathode-anode electrode circuit of said electron discharge device, a rectifier element, means to couple the output of said microphone load device to said rectifier element to produce a direct control potential having an amplitude varying in proportion to the output level of said microphone, and a filter section coupling said rectifier element between a point of reference potential of said series circuit and the control electrode of said electron discharge device to apply said direct control potential to said control electrode to maintain said output level substantially constant.

An electronic circuit arrangement comprissaid microphone transformer to the input of said amplifier stage to attenuate the higher frequencies to a different extent than the lower frequencies, a rectifier element, and means coupling said rectifier element between the output of said amplifier stage and the control electrode of said electron discharge device.

An electronic circuit arrangement comprising a carbon-button microphone, a microphone transformer, an electron discharge device having cathode, control and anode electrodes, and means to apply a direct potential in. An electronic circuit arrangement including a source of input signals having an internal resistance component, a load device having an input circuit and an output circuit, a variable resistance device, means to connect said input signal source, the input circuit of said load device and said variable resistance device in series circuit relationship, means to apply a fixed potential across said series connected circuit, means to derive a direct potential proportional to the amplitude of said input signals, and means to apply said control potential to said variable resistance device in direct proportion to said input signal, thereby to vary the resistance of said series circuit in direct proportion to the amplitude of said input signal and maintain the signal level in the output circuit of said load device substantially constant.

USA en. Condenser microphone employing wide band stop filter and having improved resistance to electrostatic discharge.


US2610252A - Audio limiter circuits - Google Patents

When generating tape recordings, particularly of "live" shows, it may be quite tough to set the right recording level. This could effortlessly result in an extreme recording level and major distortion developing except if the recording level command is retained well backed off. The price one then needs to pay is a low recording level and following low signal to noise ratio. The standard method of eliminating this issue is to try using an audio limiter circuit ahead of the tape deck.

trol of audio signal levels is desired. A peak lim0 iter is a circuit which monitors the peak level of a signal. If the peak exceeds a preset limit thresh0.

Dynamic Limiter Schematic Circuit Diagram


Limiters Clipers Multiband Processesing in fm broadcast media Back. Because a limiter is actually a specialized form of audio compressor, the circuitry of audio limiters can vary tremendously in complexity from a pair of diodes to multi-stage voltage controlled amplifiers with split frequency bands. Diode-based limiters are instanteous, simpler in design and have a more accurate loudness response, but suffer from distortion in the clipping region. VCA-type limiters have low distortion, but can exhibit breathing or pumping effects from poor gain control. This article takes especial note of design principles for diode-based limiters and the wide range of clipping characteristics. A diode has infinite resistance until the voltage across it is high enough to forwardbias it typically 0. The diode's voltage drop remains fairly constant throughout the operating range, and it is this property that is exploited in diode-based limiter circuits. Since audio signals are AC, two diodes together can symmetrically clip both the positive and negative halves of the waveform. Figure 1 The output of a hard limiter has a maximum voltage that is the forward bias voltage of the diodes. Figure 1 shows the most basic of diode limiter circuits, a hard limiter.

Audio peak limiter circuit to improve input signal

simple audio limiter circuit

The post explains 2 simple universal current controller circuits which can be used for safely operating any desired high watt LED. The universal high watt LED current limiter circuit explained here can be integrated with any crude DC supply source for getting an outstanding over current protection for the connected high watt LEDs. We know that LEDs are highly efficient devices which are able to produce dazzling illuminations at relatively lower consumption, however these devices are highly vulnerable especially to heat and current which are complementary parameters and affect an LED performance. Especially with high watt LEds which tend to generate considerable heat, the above parameters become crucial issues.

Copyright: - Web master: Kirt Blatten berger ,.

Audio Limiter Circuit


For over 70 years, Dynacord has designed and engineered professional audio electronics — products that offer unparalleled performance and premium quality, the perfect balance of power and precision. Dynacord has always been at the forefront of networked audio. With our parent company Bosch being a founding member of the OCA Alliance, we have helped to drive the development of IP technology in the audio industry, creating products that understand multiple languages and work to all standards. Dynacord is at the forefront of the IP revolution, and we are setting the standard. Whether a highly skilled engineer creating the best audio solution for a festival, or an untrained user adjusting the volume in a restaurant, we want every experience to be intuitive, simple, and straightforward.

US2420248A - Amplitude limiter circuit - Google Patents

Audio compression is a signal processing operation that reduces the volume of loud sounds or amplifies quiet sounds thus reducing or compressing an audio signal's dynamic range. Compression is commonly used in sound recording and reproduction, broadcasting, live sound reinforcement and in some instrument amplifiers. Here, we present a simple compressor circuit which is able to compress the dynamic range of any analog audio signal. The specific circuit does not amplify quiet sounds but it just compresses loud sounds. The simple compressor-limiter is an analog circuit and can be used to process only analog audio. It can be adjusted to change the way it affect sounds through two potentiometers.

This circuit is a revised version of the Audio Limiter published in the Summer The control circuitry is largely made up of simple discrete logic.

Audio Compressor Limiter Schematic

Dear sir i made this audio limiter working good but a problem the song is finished or humming is starting. In electronics, a audio limiter is a circuit that allows signals below the specified input power to pass unaffected while weakening stronger signal peaks that exceed the strength of this input. Previously, when a recording done on analog tape, when a Sound Engineer recording material that has a high dynamic changes, then he will lower the volume so that the strong dynamics will not result in distortion.

Simple audio limiter

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We use Cookies to give you best experience on our website. By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. Please see our Privacy Policy for more information. The SA is available in 20 , to the famous NE The audio output is buffered. The RSSI output has an internal amplifier with the feedback pin accessible.

For example if someone drops a microphone in a pa system the audio pulse generated could blow the loudspeakers. A limiter can prevent this.

Power Supply Current Limiter Circuits

Limiter circuit design help. I recently breadboarded this audio signal limiter circuit from ESP see figure 2 in the link : Fast Audio Peak Limiter It's very subtle and it sounds okay, but only if you don't adjust the limiter threshold. I added a 10k POT in series with the 4. Can someone recommend a simple limiter schematic that would be better? Thank you!

2 Best Current Limiter Circuits Explained

This circuit will limit the level of an audio signal to a certain maximum. If the input level exceeds a certain value, the output level is kept constant. The circuit can be used to prevent audio overload in transmitters, audio webcast systems, recording devices, etc. Figure 1: Circuit diagram of the limiter.




Comments: 3
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  1. Leo

    It does not quite fit me. Who else can suggest?

  2. Hurste

    While very well.

  3. Vobei

    In my opinion, he is wrong. I'm sure. We need to discuss.