Arrow sound indicator on LCD display. Details and setup

Printed circuit board with components and instructions in the package.
This set will allow you to collect led indicator output power of UMZCH. The device allows you to roughly estimate output power amplifier during operation. And if there are several channels, then identify possible imbalances in their work. In addition, it will liven up the front panel of your amplifier.

The indicator is made on a specialized chip LM3915N, which is led driver with internal buffer amplifier, comparator and source reference voltage. The principle of operation of the microcircuit is based on comparing the magnitude of the input signal with an internal reference voltage source. To expand the range input voltages The microcircuit is equipped with a programmable divider R5, R6.
Resistor R7 limits the current passing through the LEDs and thus facilitates the thermal operation of the microcircuit.
A peak detector is assembled on transistor VT1, which allows you to increase the accuracy of measuring the input signal and prevent flickering of the LEDs during transient values of the signal value.
Resistor R1 can be used to adjust the sensitivity of the indicator within small limits and take into account the ULF load resistance.
Jumper JP1 switches the microcircuit display mode - “dot” or “ruler”. In the first case, the magnitude of the input signal is displayed by one LED, in the second, the microcircuit forms a luminous column of LEDs.

Characteristics:
Number of displayed power levels: 10 pcs.;
Rated voltage power supply: DC 12 V;
Rated current consumption (silent mode): 10 mA;
Minimum displayed signal value: -27 dB;
Maximum displayed signal value: 0 dB;
Input impedance: 100 kOhm;
Assembly difficulty: 1 point;
Assembly time: About 1 hour;
Operating temperature range: 0...+45 degrees Celsius;
Relative humidity: 5...95% (without condensation);
Device dimensions: 56 x 46 x 17 mm;
total weight set: ~35 g.

Contents of delivery:
Printed circuit board;
A set of radio components;
Roll of tubular solder POS-61 (0.5 m);
Operating instructions.

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Hello, friends!

In continuation of the articles on amplifiers, I think the circuit of a logarithmic signal level indicator will also come in handy. This device Based on the LM3915 microcircuit in the amount of two pieces (each microcircuit works on its own channel), you can see detailed information about the microcircuit, the recommended supply voltage is 12V. The LM358 chip acts as a pre-amplifier. detailed information about the microcircuit.

In place of LM3915, you can use the following similar microcircuits: LM3914 and LM3916. It is worth considering that the jackal chip 3914 is linear, the LEDs light up in steps of 3 dB, and the steps 3915 and 3916 are logarithmic.

In place of LM358, you can use the following similar microcircuits: NE532, OP04, OP221, OP290, OP295, OPA2237, TA75358P, UPC358C.

Advantages of this device

Easy to manufacture
Reliability

Flaws

High cost of the microcircuit. This drawback is eliminated by purchasing radio components in China.

Stereo signal level indicator circuit

Signal level indicator circuit board

List of radio components

Microcircuits. To install microcircuits on the board, I recommend purchasing an additional DIP18 socket and installing the microcircuits into the socket last. In order to reduce the likelihood of failure of the microcircuit due to static electricity when it is installed on the board.

LM358 — 1 piece
LM3915 - 2 pcs.

Resistors

trimming resistor RV1 and RV2 - 100 kOhm - 2 pcs.
R1, R2 - 22kOhm -2pcs
R5, R6 - 220 kOhm - 2 pcs
R3, R4 - 1kOhm - 2 pcs
R7, R8 - 47kOhm -2 pcs
R9, R11 - 1.3kOhm -2pcs
R10, R12 -3.6 kOhm — 2 pcs.

Capacitors

1.0 mF - 4 pcs
electrolytic capacitor 100mF x 32V - 1 piece

1N4148 - 4 pcs.
LEDs - 10 pcs. Selected according to taste with a supply voltage of 3V. We recommend choosing the last two LEDs in a different color.

If you have any questions about this article, please write to the site administrator.

The New Year holidays provided an opportunity to relax a little.

For me best vacation— make some new light toy.

I hope you find it as interesting as it is for me.

Having certain developments in hand, the result was a weekend design.

The highlight of the design is its amazing simplicity!

Sound analysis and effects construction are assigned to the program.

Data is transferred to a very common controller via USB, from where it receives power.

And the effect was quite dynamic and spectacular: just remember “Cat’s Eye”!

A minimum of parts, a simple single-sided board and no configuration!

The hardware diagram and firmware are taken from the article “Dynamic lighting installation for Winamp.”

The circuit has been simplified according to the Chinese format - “unnecessary” current-limiting resistors have been discarded. Works!!!

And if in doubt, install resistors, I warned you!

I slightly corrected the firmware so that it is defined as a VU meter USB device:

And he laid out a new printed circuit board:

2 gadgets were assembled to indicate the level of the left and right channels.

Of course, it would be possible to assemble a stereo indicator on one Mega-8 based on the “Cat’s Eye” and get 2x9 channels.

But there is one “BUT” - separating the left and right parts in space will not be so simple and aesthetically pleasing. Well, where can I get 2 additional USB ports?

Buy an expansion board or hub! I already have 2 such boards on my computer with 5 ports each, plus 10 on board - a total of 20 ports, but I don’t need to plug anything!!!

Well, finally a program has been written to manage this disgrace.

For me this is the most interesting part turned out to be a job!

The program was written in your favorite studio on the no less beloved VBNET, although in Lately I write more and more often in C#.

As always, it has the ability to hide in the tray and register in startup. And the dynamic icon, beloved by everyone from previous designs, not only duplicates real LEDs, but also shows the presence of left and right channel connections. 12 different level display options will find their audience. It involves controlling not only the number of LEDs turned on, but also their brightness. This made them very spectacular! I think that over time it will be possible to add more effects. The program has been tested on XP/32 and 7/64. I wonder if it will work on newer versions? Looking forward to your testing!

Thank you all for your concern and all possible help!

Share information on your finished devices, send your suggestions for improvement!

Level meter for symmetrical analog audio signals MS-23AS

Level meter for symmetrical analog audio signals type MS-23AS The meter allows you to visually monitor the quasi-peak level of two signals (stereo pair or two independent signals) and display them in a visual form. LED emitters various colors with a large luminous area and a wide viewing angle provide high reliability and operator comfort. The level is displayed by a luminous chain of green, yellow and red LEDs. At levels below 0 dB the LEDs are green, above - red. If necessary, yellow divisions can be “superimposed” on the luminous chain of LEDs - either only “0 dB”, or a grid of 20-10 dB.

The pair of signals is equipped with a circuit for measuring the cross-correlation of signals, displayed as a separate two-color LED, green for in-phase signals, red for out-of-phase signals. The correlometer can be turned off when working with independent signals.
A separate switch on the rear panel "GND lift" disconnects pins 1 of the input and output connectors from the device body, which can be useful in difficult conditions ground interference.
In addition to measurement and indication, the device allows you to detect long pauses or low levels in signals and signal them with an audible signal and flashing scale LEDs. This function can be disabled either per channel or completely. The level of reduction can also be selected by a switch on the rear wall - below -30 dB for more than 5 seconds or below -40 dB for more than 10 seconds. To activate the loss control function, the switch sliders on the rear panel and the buttons on the front panel are used.
Instead of controlling dropout, the front panel buttons can be used to stretch the scale at three points - -10 dB, 0 dB, +8 dB. Selecting control of loss or stretching - a switch on the rear panel.
Most switchable operating modes are selected by an eight-channel switch on the rear panel. There is also an RS-485 interface connector, which allows you to organize, if necessary, remote control functions of the meter and transmission of measured data, information about the loss to a PC or remote display panel.

Level meter for balanced analog audio signals MS-24AS2

The level meter of symmetrical analog audio signals type MS-24AS2 is intended for use in editing and on-air equipment rooms of radio and television. The meter allows you to visually monitor the quasi-peak level of two pairs of signals (two stereo pairs or four independent signals) and display them in a visual form. LED emitters of various colors with a large luminous area and a wide viewing angle provide high reliability and operator comfort. The level is displayed by a luminous chain of green, yellow and red LEDs. At levels below 0 dB the LEDs are green, above - red. If necessary, yellow divisions can be “superimposed” on the glowing chain of LEDs - either only “0 dB”, or a grid of 20-10 dB.

Wide range of measured signals (-50..+8 dB), stability of characteristics and a large number of displayed level gradations (50) guarantee high quality and ease of measurement.
The indication scale is logarithmic with a stretch around 0 dB. One division in the range -50 .. -10 dB corresponds to 2 dB, in the region of 0 dB - 0.5 or 0.66 dB. The set sensitivity levels correspond to the moment the corresponding LED starts to light.
Functionally, the indicator corresponds to a quasi-peak meter of group I according to GOST 21185-75 (DIN 45406) with an averaging time of 5 ms (-2 dB) and a decay of 1.7 s/20 dB.
Each pair of signals is equipped with a circuit for measuring the cross-correlation of signals, displayed in the form of a separate glowing column of LEDs, green for in-phase signals, red for anti-phase. The entire linear scale of 23 three-color LEDs corresponds to the correlation coefficient range -1..+1. The measured value is indicated when the level of both signals of the stereo pair is not lower than -30 dB. The rise and fall time of the readings is 3 seconds. The correlometer can be turned off when working with independent signals.
The inputs of all channels can be configured as either high-impedance, pass-through (10 kOhm), or low-impedance (600 Ohm). Switching the configuration using switches on the rear wall. The level of input signals can be adjusted stepwise (+6 dB) - by jumpers on the board, under the cover, and smoothly - by “slotted” regulators located on the rear wall next to the corresponding connector.
When used “pass through”, the indicator passes the signal without distortion, because The output connectors are directly connected to the input connectors, which allows you to connect the device to a line break.
In addition to measurement and indication, the device allows you to detect long pauses or low levels in signals and signal them with an audible signal and flashing scale LEDs. This function can be disabled either per channel or completely. The level of reduction can also be selected by a switch on the rear wall - below -30 dB for more than 5 seconds or below -40 dB for more than 10 seconds.
Most switchable operating modes are selected by an eight-channel switch on the rear panel.
The level indicator is made in the form of one 19-inch block with a height of 1U and dimensions of 483x125x44 mm, intended for installation in a rack.
Device power supply - 220+20V, 50 Hz, not redundant.

Audio signal level meter MS-25AS

The MS-25AS audio signal level meter is intended for use in editing and on-air equipment rooms of radio and television.

The meter accepts analog balanced signals or digital serial audio signals in AES-EBU (AES3) format with a sampling rate of 48 kHz only. (This restriction will be removed in future versions.)
The meter allows you to visually monitor the quasi-peak level of two signals (stereo pair or two independent signals) and display them in a visual form.
The level is displayed by a luminous chain of green, yellow and red LEDs. At levels below 0 dB, the LEDs are green, and above 0 dB, the LEDs are red. If necessary, yellow divisions can be “superimposed” on the luminous chain of LEDs - either only “0 dB”, or a grid of 20-10 dB.
A wide range of measured signals (-50..+8 dB for analog and -60..0 dBfs for digital signals), stability of characteristics and a large number of displayed level gradations (48) guarantee high quality and convenience of measurements.
The level indicator is made in the form of one block measuring 240x100x80 mm, intended for installation on a horizontal surface.
The power supply of the device is 12V, 0.3A, the kit includes a network adapter 220+20V, 50 Hz.
Number of inputs 2 analog, 1 stereo AES|EBU
Type of inputs differential, electronic
Input impedance (selectable by switch) 600 ohms / 10 kohms, 110 ohms
Nominal input level (selectable by switch) +0 dBm (factory setting)
Limits of regulation of nominal sensitivity (level "0 dB") -6..+6 dBm
Quasi-peak detector integration time 5 ms (-2 dB)
Indication decay time 1.7 sec / 20 dB, 5 sec full scale
Maximum input level 10 V
Permissible overloads (duration up to 5 μs) up to 200 V
Number of level indication stages 48
Scale type piecewise logarithmic with extension around 0 dB
Geometric scale length 127 mm
Measuring range -50 ..+8 dB
Operating frequency range 20 Hz-20 kHz at 0 dB level
Measurement accuracy at 0 dB level, 1 kHz + 0.1 dB
Measurement accuracy at -40 dB, 1 kHz + 2 dB
Unevenness of sensitivity in the range 20Hz-20 kHz (at 0 dB) less than 1 division of the main scale
Type of input/output connectors XLR (“Cannon”)
Supply voltage 10-16V 0.3A
Overall dimensions 240x100x88 mm

Four-channel monitor of symmetrical analog stereo audio signals MS-26AK

Designed for use in editing and on-air equipment rooms of radio and television.
Allows you to listen, measure the level of four analog stereo audio signals (four stereo pairs or eight independent signals) and display them in a visual form.
The level is displayed by a luminous chain of green, yellow and red LEDs. At levels below 0 dB, the LEDs are green, and above 0 dB, the LEDs are red. The indication scale is logarithmic with a stretch around 0 dB.
Each pair of signals is equipped with a circuit for measuring the cross-correlation of signals, displayed as a separate two-color LED, green for in-phase signals, red for out-of-phase signals. The correlometer can be turned off when working with independent signals.
The inputs of all channels can be configured either as high-impedance, “pass-through” (10 kOhm - as standard), or as low-impedance (600 Ohm).
The level of input signals can be adjusted stepwise (+6 dB) - with a switch on the board, under the cover, and smoothly - with "slotted" regulators located under the cover of the device.
In addition to listening, measuring and indicating, the device allows you to detect long pauses or low levels in signals and signal them with an audible signal and flashing scale LEDs. This function can be disabled either per channel or completely.
Made in the form of one 19-inch block with a height of 2U and dimensions of 483x250x88 mm, intended for rack installation.
Device power supply - 220 V ± 10%, 50 Hz.

Single-channel symmetrical audio signal level indicator MS-11AS

Dynamic control of quasi-peak level symmetrical sound signal and displaying it in a visual form using LED emitters of various colors with a large luminous area and a wide viewing angle.
The input can be configured as either high impedance, pass-through, or low impedance (600 ohms) using a switch on the rear panel.
Designed for use in editing and on-air equipment rooms of radio and television.

Two-channel symmetrical audio signal level indicator MS-21AS

Dynamic control of the quasi-peak level of two independent symmetrical audio signals and display them in a visual form using LED emitters of various colors with a large luminous area and a wide viewing angle.
The inputs of both channels can be independently configured as either high-impedance, pass-through, or low-impedance (600 ohms) using switches on the rear panel.
When used "pass-through" signal transmission without distortion despite the absence or presence of mains power.
Opportunity smooth adjustment nominal sensitivity, which allows you to accurately set the required sensitivity depending on the type of signal source.
Protected location of sensitivity regulators - on the rear panel "under the slot".
Designed for use in editing and on-air equipment rooms of radio and television.
Functionally corresponds to a quasi-peak meter of group II according to GOST 21 185-75.
Metal case, dimensions 483x125x44 (19", 1U).
Three-wire power supply 220÷230 V.

Company LES-TV (Laboratory Electronic Systems) released its first products in 1992. Currently, more than 30,000 units of television equipment have been delivered to users. Over the years, switching and control equipment from LES has become the de facto standard for domestic television studios. The company's products are used in large television centers and small regional studios in broadcasting, editing and production control rooms.

Several reasons why you should contact LES-TV:

When developing new products, the company's specialists use the most modern element base, which ensures the quality and reliability of the products.
The company's products are created in close contact with direct consumers: video engineers and camera operators.
The LES equipment is distinguished by its ergonomics and modern design;
The company provides its customers with a free 2-year warranty on all manufactured equipment;
The company advises its clients on the construction of studio complexes using our equipment.

LM3915 – integrated circuit (IC) manufactured Texas companies Instruments reacts to changes in the input signal and outputs a signal to one or several of its outputs. Thanks to its design feature ICs have become widespread in LED indicator circuits. Since the LED indicator based on LM3915 operates on a logarithmic scale, it found practical use in displaying and monitoring the signal level in audio amplifiers.

The LM3915 should not be confused with its relatives LM3914 and LM3916, which have a similar layout and pin assignment. The 3914 series IC has a linear characteristic and is ideal for measuring linear quantities (current, voltage), while the 3916 series IC is more universal and is capable of driving different types of loads.

Brief description of LM3915

The LM3915 block diagram consists of ten identical operational amplifiers operating on the comparator principle. The direct inputs of the op-amp are connected through a chain of resistive dividers with different resistance values. Thanks to this, the LEDs in the load light up according to a logarithmic dependence. The inverse inputs receive an input signal, which is processed by a buffer op-amp (pin 5).

The internal structure of the IC includes a low-power integrated stabilizer connected to pins 3, 7, 8 and a device for setting the glow mode (pin 9). The supply voltage range is 3–25V. The reference voltage can be set in the range from 1.2 to 12V using external resistors. The entire scale corresponds to a signal level of 30 dB in 3 dB steps. The output current can be set from 1 to 30 mA.

Sound indicator circuit and principle of its operation

As can be seen from the figure, the fundamental electrical diagram The sound level indicator consists of two capacitors, nine resistors and a microcircuit, the load for which is ten LEDs. For easy connection of power and audio signals, it can be supplemented with two solder connectors. Anyone, even a beginner radio amateur, can assemble such a simple device.

A typical connection provides power from a 12V source, which is supplied to the third pin of the LM3915. It, through the current-limiting resistor R2 and two filter capacitors C1 and C2, goes to the LEDs. Resistors R1 and R8 serve to reduce the brightness of the last two red LEDs and are optional. 12V also comes to the jumper, which controls the operating mode of the IC through pin 9. In the open state, the circuit operates in the “point” mode, i.e. one LED corresponding to the input signal lights up. Closing the jumper switches the circuit to the “column” mode, when the input signal level is proportional to the height of the illuminated column.

A resistive divider assembled at R3, R4 and R7 limits the input signal level. More precise adjustment is carried out by multi-turn trimming resistor R4. Resistor R9 sets the bias for the upper level (pin 6), exact value which is determined by resistance R6. The lower level (pin 4) is connected to the common wire. Resistor R5 (pin 7.8) increases the reference voltage and affects the brightness of the LEDs. It is R5 that sets the current through the LEDs and is calculated using the formula:

R5=12.5/I LED, where I LED is the current of one LED, A.

Sound level indicator works in the following way. At the moment when the input signal overcomes the lower level threshold plus the resistance at the direct input of the first comparator, the first LED (pin 1) will light up. A further increase in the sound signal will lead to the comparators being activated one by one, which will be indicated by the corresponding LED. To avoid overheating of the IC case, the LED current should not exceed 20 mA. Still, this is an indicator, not a New Year's garland.

Printed circuit board and assembly parts

The printed circuit board of the sound level indicator in lay format can be downloaded. It has dimensions 65x28 mm. Assembly requires precision parts. Resistors type MLT-0.125W:

R1, R5 R8 – 1 kOhm;
R2 – 100 Ohm;
R3 – 10 kOhm;
R4 – 50 kOhm, any trimmer;
R6 – 560 Ohm;
R7 – 10 Ohm;
R9 – 20 kOhm.

Capacitors C1, C2 – 0.1 µF. It is recommended to solder the LM3915 IC not directly, but through a special socket for the chip. The load can use ultra-bright LEDs of any color, even purple. But these are personal aesthetic preferences. To display a stereo signal, you will need two identical boards with independent inputs. More details about the LM3915 can be found in technical description Here.

The performance of this indicator has been proven in practice by many amateur radio clubs and is still available in the form of MasterKits.