VM-AI1i User guide · 2. Peak Fall – Show the peak. After a hold time (800ms) the peak “fall”...

Mectronics, Inc. VU-Meter mod. VM-AI1i User Guide V1.2

© 2010-2015 Mectronics, Inc. 1

VM-AI1i© User guide

VM-AI1i is a useful VU-Meter/ Audio meter that has several features. This user manual shown these

features.

Display Mode (DM)

Display Mode indicates how VM-AI1i “show” current audio level. VM-AI1i has two display modes:

1. Bar – turn on all leds from first to current-level led;

2. Dot – turn on only current-level led and previous;

The default DM value is Bar.

Figure 1 - Bar mode vs Dot mode

Peak Mode (PM) Peak Mode indicates how VM-AI1i treat and “shown” the temporary maximum audio level (aka peak).

There are four modes:

1. Peak Off – Simply don’t show the peak;

2. Peak Fall – Show the peak. After a hold time (800ms) the peak “fall” in automatic (95ms @ point);

3. Peak Hold with auto reset – Show the peak. After a hold time (3sec) the peak is reset in automatic;

4. Peak Hold with manual reset – Show the peak. The peak is reset only by pressing the button S2;

The default PM value is Peak Fall.

Meter Scale (MS)

Meter Scale indicates which measuring scale is used by VM-AI1i. There are four scales:

1. Scale N1 – (Extended) ANSI VU-Meter specification. It’s the classic VU-Meter scale and has 45dB of

dynamic.

2. Scale N2 – 1dB @ Point; Useful for fine audio measuring. Has 24 dB of dynamic.

3. Scale N3 – 2dB @ Point; Useful for audio measuring. Has 48 dB of dynamic.

4. Scale N4 – Mectronics’s custom scale;

The default MS value is Scale N1.

In the following picture there are the specification of scales:



Figure 2 - Meter scales specifications. *Note: the scale is implemented in the respect of "delta" between the

divisions. Assuming 0dB as "+3dB" (full scale of VU-Meter), the ticks are: +3dB, +2dB, +1dB, 0dB, -1dB, -2dB, -3dB,

-4dB, -5dB, -6dB, -7dB, -8dB, -10dB, -12dB, -14dB, -16dB, -18dB, -20dB, -23dB, -26dB, -29dB, -32dB, -35dB, -38dB. So

user must set 0dB as level to turn-on the 21th led.

Decay Speed (DS) Decay Speed indicates how many “fast” are the “falling” (also called “release”) of bar (dot). Fast releases

speeds are useful to monitoring fast peak and spikes; slow speed instead are good to measure the average

of audio signal. VM-AI1i has up to 7 decay speeds:

1. UltraFast – 8ms @ point, that is 192ms for the complete bar;

2. SuperFast – 16ms @ point, that is 384ms for the complete bar;

3. Fast – 30ms @ point, that is 720ms for the complete bar;

4. Normal – 56ms @ point, that is 1.34sec for the complete bar;

5. Slow – 60ms @ point, that is 1.44sec for the complete bar;

6. SuperSlow – 76ms @ point , that is 1.82sec for the complete bar;

7. UltraSlow – 96ms @ point, that is 2.3sec for the complete bar;

The default DS value is Fast.



Brightness This new feature allow user to select up-to 10 level of brightness of the leds. Brightness varies from 100%

to 10%, in 10 steps. The default brightness is 80%.

Connections and adjustment

This section shows how to connect power supply and signals to the VM-AI1i and adjust it.

Power supply connection To function properly, VM-AI1i requires a (minimum) 9VDC power supply (maximum 12V). In the kit a

2-way header is provided to connect the power supply source, but the PCB can accept also a classic DC Jack

(positive tip, like this: http://www.mouser.com/ds/2/222/KLDX-0202-x-184473.pdf). NOTE: This jack is not

provided with the kit. A Schottky barrel diode prevent accidental polarity inversion, and on-board charge

pump IC provides the negative voltage for the operational amplifiers. Power supply connections are located

near IC4 (TC1044S): the positive connection is internal, the negative external. Figure 3 shown how connect

the power supply source to VM-AI1i.

Figure 3 – Power supply connections.

Signal connection Signal input connections are located near the two input trimmer (R1, R2). As shown the top silk, R-input is

external, Common (Ground) central, L-Input is internal. In the kit a 3-way header is provided to connect the

signal sources, but the PCB can accept also a classic 3.5mm stereo audio jack (like this:

http://www.switchcraft.com/Drawings/35rapc__hn2_cd.pdf). NOTE: This jack is not provided with the kit.

Figure 4 – Input connections.

Adjustment VM-AI1i has an high sensitivity, indeed is possible turn on all led with a very low audio signal:

220mVRMS. (This mean that the minimum signal needed to turn-on the first led, using the MS = Scale N3, is

only 1mVRMS!). Using a 50k trimmer as input attenuator is also possible drive the VM-AI1i with high

powers, up to 50-60VRMS (that corresponds to about 300-450WRMS @ 4Ω). Adjust these trimmers for desired

“0dB” level.



Setup

VM-AI1i has a user-friendly and very simple setup interface that consist in only two buttons:

• S1 – Enter in Setup Mode / Change meter parameter / Store configuration

• S2 – Reset configuration / Change parameter value / Reset peak (when VM-AI1i is in PM = Peak

Hold with manual reset)

Figure 5 - VM-AI1i buttons

To enter in Setup Mode, press the S1 button for at least 1sec. The display are automatic cleared and first

meter parameter (DM) and his value are shown. How? Simply! The L-Bar indicates current parameter (DM,

PM, MS, DS) and the R-Bar indicates the value of this current parameter (for more information, see next

section Setup Visualization). Setup of Brightness instead turn-on all leds.

To navigates through the meter parameters press the S1 button (for at least 0.2s and less of 2sec). The

sequence are:

Figure 6 - Setup: meter parameters navigation.

Once entered in setup mode, using S2 button it’s possible navigate through the values of current

parameter, starting from current value. With S1, pressed for a time greater than 2sec, it’s possible save and

store (in the MCU’s EEprom) the configuration. Finally, to reset VM-AI1i, is necessary to press S2 (when

VM-AI1i is not in Setup Mode) for a time greater than 3secs. Reset restore the default configuration.

In the following picture is shown all the VM-AI1i setup workflow.



Figure 7 - VM-AI1i Setup workflow.



Setup visualization

In following pictures are shown how VM-AI1i displays the current setup parameter and its values.

Figure 8 - Setup: Display Mode

Figure 9 - Setup: Peak Mode



Figure 10 - Setup: Meter Scale

Figure 11 - Setup: Decay Speed (1 of 2)



Figure 12 - Setup: Decay Speed (2 of 2)

Figure 13 - Setup: Brightness. All leds are turned-on.



Bill of Material/Assembling instruction

This section shown the required components of elaboration unit of VM-AI1i and the assembling

instructions.

Resistors

• R1, R10 (2X): 50kΩ trimmer

• R2, R11 (2X): 49.9 kΩ, ¼ W, ±1% Yellow-White-White-Red-Brown

• R3, R12, R19, R21 (4X): 6.65 kΩ, ¼ W, ±1% Blue-Blue-Green-Brown-Brown

• R4, R5, R6, R8, R13, R14, R15, R17 (8X): 20 kΩ, ¼ W, ±1% Red-Black-Black-Red-Brown

• R7, R16 (2X): 10 kΩ, ¼ W, ±1% Brown-Black-Black-Red-Brown

• R9, R18, R23 (3X): 100 kΩ, ¼ W, ±1% Brown-Black-Black-Orange-Brown

• R20, R22 (2X): 1 kΩ, ¼ W, ±1% Brown-Black-Black-Brown-Brown

• R24…R29 (6X): 2.2 kΩ, ¼ W, ±1% Red-Red-Black-Brown-Brown

Capacitors

• C1, C4 (2X): 1uF/50V Electrolytic.

• C2, C5 (2X): 120pF Ceramic.

• C3, C6 (2X): 1uF/50V Film.

• C7 (1X): 470uF/25V Electrolytic.

• C8, C9, C11, C13, C15, C16, C19 (7X): 100nF/63V Film.

• C10 (1X): 10uF/25V Electrolytic.

• C12, C14 (2X): 100uF/25V Low-ESR Electrolytic.

• C17, C18 (2X): 220nF/63V Film.

Discrete semiconductors

• D1…D8 (8X): 1N4148 Switching diode.

• D9 (1X): SB140 Schottky barrel diode.

• T1…T6 (6X): BC337 NPN g.p. transistor.

Integrated semiconductors

• IC1 (1X): TC1044S Charge pump.

• IC2 (1X): TL072 Dual low-noise operational amplifier.

• IC3 (1X): LM7805 5V Voltage regulator.

• IC4 (1X): TL074 Quad low-noise operational amplifier.

• IC5 (1X): VM-AI1i v3.5/2015 Preprogrammed MCU.

Mechanical/ spare parts

• JP1E (1X): 8Pin Male header.



• JP2E, JP3E (2X): 3Pin Male header.

• JP4E (1X): 6Pin Male header.

• S1, S2 (2X): NO Tactile buttons.

• 2X 8Pin 2.54mm/0.1in IC socket.



• JP1D (1X): 8Pin Female header.∗

• JP2D, JP3D (2X): 3Pin Female header.

• JP4D (1X): 6Pin Female header.

∗ In italics there are the display units mechanical parts.



Assembling instructions (Elaboration Unit) Assembly VM-AI1i is very simple, all you need is a good soldering station/iron, a good (multicore flux)

solder and…patience (for good, final, result ).

In this section, is shown the right mounting order of VM-AI1i elaboration parts.

Figure 14 – 1N4148 diodes.

Figure 15 – 49.9kΩ resistors.

Figure 16 – 6.65kΩ resistors.



Figure 17 - 20kΩ resistors.






Figure 21 – SB140 Schottky barrel diode.

Figure 22 – 120pF ceramic capacitors.

Figure 23 – LM7805 Voltage regulator.

Figure 24 – 50kΩ trimmers.



Figure 25 – 8Pin socket (for TC1044S). Reference is Top-Right.

Figure 26 – 8Pin socket (for TL072). Reference is Bottom-Left.

Figure 27 – 14Pin socket (for TL074). Reference is Top-Right.

Figure 28 – 20Pin socket (for VM-AI1i v3.5/2015 Preprogrammed MCU). Reference is Top-Right.



Figure 29 – 100nF/63V film capacitors.

Figure 30 – 220nF/63V Film capacitors.

Figure 31 – BC337 transistors.

Figure 32 – N.O. Tactile buttons.



Figure 33 – 1uF/50V Film capacitors.

Figure 34 – power (top) and audio signals (bottom) connectors.

Figure 35 – 1uF/50V electrolytic audio grade capacitors.

Figure 36 – 10uF/50V electrolytic capacitor.



Figure 37 – 100uF/25V low-ESR electrolytic capacitors.

Figure 38 – 470uF/25V electrolytic capacitor.

Figure 39 – Male headers. Note, these parts are mounted in the bottom layer.

Assembling instructions (Display Unit) The display of VM-AI1i is extremely versatile, it allow up to five configurations of the leds. In fact the

columns can be spaced by:

• 2.0cm, 48Leds, internal

• 2.9cm, 48Leds, external

• 2.4cm, 48Leds, left

• 2.4cm, 48Leds, right

• 2.4cm, 96Leds

In this section, is shown the right mounting order of VM-AI1i display parts.



Figure 40 – display unit resistances.

Figure 41 – Internal (2.0cm) 48 Leds mode. Look carefully the polarity of leds!

Figure 42 – External (2.9cm), 48 Leds mode.

Figure 43 – Mid-Left (2.4cm), 48 Leds mode.



Figure 44 – Mid-Right (2.4cm), 48 Leds mode.

Figure 45 – 96 Leds mode.

Figure 46 – Female headers. Note, these parts are mounted in the bottom layer.

Figure 47 – (Display unit bottom layer) Pad to solder (short circuit) in internal, 48 leds, mode.



Figure 48 – (Display unit bottom layer) Pad to solder (short circuit) in external, 48 leds, mode.

Display Unit resistances

The values of the resistances used in the display unit depends by various factor, such

• How many leds for point are used;

• Colour of leds;

• Type (hi brightness?) of leds.

But, to avoid mistakes, only one value is provided for configuration:

• 33Ω, in 96 leds mode;

• 127Ω, in 48 leds mode.

These values allow a current of about 20mA through the leds.

VM-AI1i User guide · 2. Peak Fall – Show the peak. After a hold time (800ms) the peak “fall”...

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Transcript of VM-AI1i User guide · 2. Peak Fall – Show the peak. After a hold time (800ms) the peak “fall”...