VU Meter Warm Back Light
Meter sensitivity: 500UA
Header: 650 ohm internal resistance
Table 8V125mA backlight: incandescent light bulbs, AC and DC can.
Mounting hole diameter: 45mm
Wiring instructions: header back 2 groups of terminals, a group of yellow VU positive and negative output terminal of the drive plate. Following a group of white backlight power supply terminals.
The header for our special needs, resistance and sensitivity of the VU header according to the formal specifications for design, the damping medium, the pointer swing speed of response to a proper extent, to avoid the use of ordinary VU table table instead of current overshoot or procrastination phenomenon.
To extend the service life of the backlight lamp, you can use the following methods:
1, in the backlight brightness to meet the requirements, reduce the operating voltage, can significantly extend the life.
2, AC power supply from 8 to 10V, series of euro to 50 euro current limiting resistance, reduce the impact on the filament when starting on the 10.
3, the use of soft start circuit, such as the common LM317 can be produced, the voltage gradually rose to normal, but also can reduce the impact of the current on the filament, extend the service life.
Due to the high sensitivity level meter, a series resistor can be easily changed to voltage meter, I use a 200K potentiometer series, digital meter calibration, easily adjusted to a wide range of DC voltage meter.
Used to measure the cathode resistance voltage of the single ended amplifier, and then monitor the working current is also very convenient oh.
For example, the cathode resistor is 1K, current of 40MA, while the cathode voltage is 40V, by adjusting the potentiometer, the header pointer in the 0dB position, such as the current deviation from the normal working point, the deflection of the pointer can be clearly displayed.
1, designed for audio level testing and design of an integrated circuit chip imports,
includes the square root of a dynamic index compression circuit (Example: Input 1V, the 1V;
input 4V, the 2V; input 9V, the 3V), taking into account the dynamic and precision
instruction pointer swing moderate, avoiding the small signal pointer does not move, the
large signal pointer backing of the state.
2, no independent power supply, power supply leads directly from the original, as compared
with TA7318P / TA7332P, reduce the cost of a transformer, while inside the chassis takes up
less space because the half, the installation is more convenient and flexible.
3, the circuit designed, has the following characteristics:
Enter the installation of a 1ow—pass filter circuit to filter out high frequency
interference, power supply for harsh environments (such as car audio system).
Output sensitivity adjustable, for a variety of specifications header.
The most common 12VDC power supply, easy to use in-vehicle device and PC computers.
Has a power reverse polarity protection.
Have energized pointer protection against boot pointer base, extend header life.
Use 0.5W metal film resistors, large power margin to ensure reliable and stable work
[Input Sensitivity]: 400Hz input audio signal with Fluke 8025B digital multimeter range
measuring AC mV, the input: 97mV, 39 level meter to + 3dB position.
[Power supply voltage]: DC12V 0.12A.
[PCB Size]: 5.2cm X 6.3cm.
[Backlight power supply terminals]: Available DCl0 to 12V 50MA. Power for small bulbs
[Drive VU meter, level meter Sensitivity]: Recommended 500UA sensitivity, 630 European
resistance. At this point the best damping effect, the level meter damping effect other
specifications will be different, the need for further adjustments.
Description: The supply voltage must be strict to ensure 12VDC, l2VDC, although more than
a short - term work, but a long time will burn protection circuit. Power connection Wiring
must be carried live operation of this man—made damage is not covered by the warranty
Instruct ions for use:
1, the input section:
Lin, 0, Rin, is an audio signal input terminal for CD audio output connected to the left
and to the right channel. Or an output terminal connected to the first input terminal
selection stage, the former should not connected to the output stage output or volume
2, the output section:
Two VU Meter side ”+” and "—" terminal as an output, respectively, should be connected to
Two level meter the ”+' and '-” terminal.
Drivable level meter sensitivity recommendation: DC 100 microamps to 500 microamps. Should
not exceed 1mA.
Board 2 500 European blue 3296 series potentiometer can adjust the sensitivity of the two
separately header. Clockwise, sensitivity can be improved.
LA, LB for the backlight power supply terminals, RA, RB of the other set backlight power
Model Number: VU45
Maximum Power Per Channel: 10W
Channels: 2 (2.0)