Wiring And Schematic

Monday, September 15, 2014

10 LED Bar Dot VU Meter Circuit based LM3915

Build a 10 LED Bar Dot VU meter schema based LM3915. It differs in many respects from other applications on the same chip. The schema is intended for those who want a VU meter that is connected directly to the output of an power amplifier.

10 LED Bar Dot VU Meter Circuit based LM3915 Circuit Diagram

It’s possible to adjust the sensitivity to work with amplifiers that have different output power, you just need to change the value of R1 according to Table 1. In case you did’n find the exact resistor value, then choose the next standard value (for example if you cannot find 33K ohm, then find the 36K ohm), or if you want maximum accuracy you need to put resistors in series or in parallel to achieve the correct value.

You can use various types of LEDs (round or square) to get the visual and aesthetic result you want. The switch S1 will allow you to choose whether VU meter will work as a bar or one by one (dot). In position ON [closed switch], the LED operation is Bar, while in position OFF [open switch], the LED operate in Dot. In Bar mode, the power consumption rises because all of the LED will be work and can reach up to 150mA.

For amplifier with two channels is obvious that we should build two identical diagram, one for each channel. The operating voltage of the schema is +12 V. Taking this trend should be done by the tendency of the amp. Usually amps work with voltages which higher than +12 Volts for the schema. For this reason, we must added a component which can decrease, regulate and stabilize the +Vp voltage at +12 Volts. The component we are used is IC2 (LM317) which is an adjustable voltage regulator and stabilizer.

Using a small brushing is necessary because the differences in the potential entry; output is large so that we develop high levels of temperature. The use of R5 helps in voltage drop to descend the voltage at the input of IC2 at lower levels. The calculation of this resistance is more empirically using Ohm’s law. The voltage at the input of IC2 must be higher than +16 Volts. For example, if the voltage of the amplifier is +50 Volts, we should have a voltage drop 50-16 = 34 Volts on the resistance R5. For the electric current, 50mA average is needed by the schema [may be up to 150mA], the value of R5 = V / I = 34/0.05 = 680 ohms 2W. You may need to increase or decrease this value by trials. Because the resistor is going to heat up, then it will be better to put some distance from the PCB.

It will be better to set up and measure the output vltage of the IC2 by adjusting TR1 first, you need yo remove IC1 to secure the IC1. If you are able to supply the stabilized +12 V from somewhere in the amplifier schema, then you’ll need to remove the R5, the IC2 and materials inside the dotted line.

PCB layout design:

Saturday, September 6, 2014

Simple Audio Power Meter Circuit

This simple schema indicates the amount of power that goes to a loudspeaker. The dual-color LED shows green at an applied power level of about 1 watt. At 1.5 watts it glows orange and above 3 watts it is bright red. The schema is connected in parallel with the loudspeaker connections and is powered from the audio signal. The additional load that this represents is 470 Ohm (R1//R3) will not be a problem for any amplifier. During the positive half cycle of the output signal the green LED in the dual-color LED will be turned on, provided the voltage is sufficiently high.

At higher output voltages, T1 (depending on the voltage divider R2/R1) will begin to conduct and the green LED will go out. During the negative half cycle the red LED is driven via R3 and will turn on when the voltage is high enough. In the transition region (where T1 conducts more and more and ‘throttles’ the green LED as a result) the combination of red/green gives the orange colour of the dual-LED. By choosing appropriate values for the resistors the power levels can be adjusted to suit.

Circuit diagram:

simple-audio-power-meter-schema-diagram1

Audio Power Meter Circuit Diagram

The values selected here are for typical living room use. You will be surprised at how loud you have to turn your amplifier up before you get the LEDs to go! The resistors can be 0.25 W types, provided the amplifier does not deliver more than 40 W continuously. Above this power the transistor will not be that happy either, so watch out for that too. Because T1 is used in saturation, the gain (Hfe) is not at all important and any similar type can be used. The power levels mentioned are valid for 4-Ohm speakers. For 8-Ohm speakers all the resistor values have to be divided by two.

Source :Streampowers

Thursday, September 4, 2014

Stereo balance meter 2

Description

Outputs from each channel are fed to the two inputs of ICl connected as a differential amplifier. IC2 and 3 are driven by the output of ICl. Output of ICl is connected to the noninverting inputs of IC2 and 3. If the output of ICl approaches the supply rail, the outputs of ICs 2 and 3 will also go high, illuminating LED3. This would happen if the right channel were dominating. If the left channel was dominant, the outputs of ICs 2 and 3 would be low, illuminating LED1. If the two channels are equal in amplitude, the outputs of ICs 2 and 3 would be high and low respectively, lighting up LED2.

Circuit Diagram

Stereo balance meter 2

Monday, August 18, 2014

Minimalist Dip Meter

Minimalist Dip Meter Circuit Diagram. In days gone by a radio amateur always had a dip meter close to hand in his ‘shack’. Now that people can afford oscilloscopes, the poor old dip meter has lost its importance and is frequently no longer to be seen. Actually this is a shame because many tasks are much easier to carry out with a dip meter. Anyone who’s interested (perhaps the second time around) can easily build one rapidly with this very simple but adequate schema. The interesting question is namely what do you actually need from a dip meter?

Minimalist Dip Meter Circuit Diagram

A visual display of the dip? Nope, the ‘scope can handle that task.
A large frequency scale? Not necessary, as you can connect a frequency counter for this.
A selection of coils? We don’t need these because we can use a jumper to change range (no coils to lose any more!).

The sensor coil L1 has ten turns and is wound using an AA-size battery as a former. This coil will allow us to over the range from 6 MHz to 30 MHz. With jumper JP1 open an additional ﬁxed inductance of 10 μH comes into schema. The frequency measurement range is then from 2.5 MHz to 10 MHz. The switch may be replaced by a jumper.

To take measurements you hold a resonant schema close to the sensor coil. Tune the rotary capacitor C1 slowly to and fro in order to ﬁnd the resonant frequency, at which the oscillator amplitude decreases somewhat. The frequency can then be read directly off the oscilloscope.

To obtain a very accurate measurement you can additionally connect your frequency counter to the second output.