Showing posts with label VU Meter. Show all posts

30V Volt Meter with PIC16F676

This is a simple 30V volt meter using PIC16F676 micro controller with 10-bit ADC (analog to digital converter) and three 7 segment LED displays. You can use this circuit to measure up to 30V DC.

The possible applications are on bench power supply or as a digital panel meter in various systems. PIC16F676 is the heart and brain of this circuit. The internal adc of the mcu with a resistor network voltage divider is used to measure the input voltage.

Then 3 digits of comm anode 7 segment display is used to display final converted voltage. As you can see in the schematic the displays are multiplexed with each other. It means we switch on one display and put the corresponding digit on this while other two displays are off this cycle goes for each of the displays.

Simple VU Meter 1 with Transistor

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It is a simple circuit of optical index of level of sound signals, adapted in various needs of user. It can be adapted in various levels of entry, regulated from trimmer TR1 (Level) - TR2 (Gain), then it is rectified by the D1-2 (cutting off of negative periods of signal-rectification) and drived to the main circuit of index, that it is constituted by D3...D13 , the transistors Q2-Q13 and the materials that exist around them.

Circuit Diagram:

The optical index him we take from the line of LED LD1-13. The each led turns on when the level is altered at 0,65V roughly. The requirements in current are 100 ma with complete index. We can add all units LED we want, always calculating the current where they will need the news LED.

Parts List:

Simple TV Muter

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Many households are still graced by tube-type television sets. If you want to connect one of these large tellies to your stereo system to improve the sound quality, this is usually not a problem because there are plenty of SCART to Cinch adapters available in accessory shops. However, with some sets your pleasure is spoiled by the fact that the audio outputs of the SCART connector are not muted during channel switching. This can sometimes lead to nasty signal spikes, which can cause the loudspeakers of your stereo system to emit irritating popping and cracking noises. In such cases it is a good idea to fit your system with a mute circuit.

Fortunately, the right time to activate the mute circuit is defined by the fact that the happy zapper presses buttons on the remote control to switch channels, and the remote control emits IR signals. There are even inexpensive ready-made IR receiver modules available, such as the TSOP1136 used here, which produce trains of active-low pulses in response to such signals. About the circuit: when no IR signal is present, a capacitor is charged via P2 and a diode. IC1 is a comparator that compares this IR voltage (applied to its non-inverting input on pin 3) to a voltage applied to its other input on pin 2.

TV Muter Circuit diagram :

This reference voltage, which can be adjusted with P1, determines the switching threshold of the comparator. If IC2 receives an IR signal, T2 conducts, and as a result the voltage on C1 drops rapidly below the threshold level set by P1. This causes T1 to change from its previous ‘on’ state to the ‘off’ state. As a result, the relay drops out and the audio link to the stereo system is interrupted for the duration of the noise interval. It’s all quite simple, as you can see. If you do not have a stabilized 5-V supply voltage available, you can use the circuit at the of the schematic diagram (with a 5-V voltage regulator) together with a simple (unstabilised) AC mains adapter that supplies a voltage in the range of 9 V to 12 V to the 7805 (IC3).

You can also use a relay with normally-closed contacts instead of normally-open contacts. In this case, simply swap the signals on pins 2 and 3 of IC1 so the relay pulls in when an IR signal is received instead of dropping out. This saves a bit of power because the relay is only energized during zapping. If you can’t find any worthwhile use for the second comparator of IC1, it’s a good idea to connect pin 6 to +5 V and pin 5 to ground. To improve noise immunity, you should shield the IR sensor so it is not exposed directly to light from a fluorescent fixture. link

VU Meter 1 Using with Transistor

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Here is a simple Electronic Circuit Project of VU Meter 1 with transistor Circuit. This is Simple Circuit of optical index of level of sound signals, adapted in various needs of user. It can be adapted in various levels of entry, regulated from trimmer TR1 (Level) - TR2 (Gain), then it is rectified by the D1-2 (cutting off of negative periods of signal-rectification) and drived to the main circuit of index, that it is constituted by D3...D13 , the transistors Q2-Q13 and the materials that exist around them.

VU Meter 1 Using with Transistor Circuit Diagram:

Easy Build to 8 Stage LED VU Meter

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This is a very simple 8 Stage LED VU Meter Circuit. The circuit below uses two quad voltage comparators (LM339) to illuminate a series of 8 LEDs indicating volume level. Each of the 8 comparators is biased at increasing voltages set by the voltage divider so that the lower right LED comes on first when the input is about 400 millivolts or about 22 milliwatts peak in an 8 ohm system.

8 Stage LED VU Meter Circuit Diagram:

The divider voltages are set so that each LED represents about twice the power level as the one before so the scale extends from 22 milliwatts to about 2.5 watts when all LEDs are lit. The sensitivity can be decreased with the input control to read higher levels. I have not built or tested this circuit, so please let me know if you have problems getting it working. The power levels should be as follows:

1 LED = 22mW
2 LEDs = 42mW
3 LEDs = 90mW
4 LEDs = 175mW
5 LEDs = 320mW
6 LEDs = 650mW
7 LEDs = 1.2 Watts
8 LEDs = 2.5 watts

Source: Circuits-Projects

How to build a Simple LED Volt Meter

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This is a Simple LED Volt meter to Monitor the charge level in Lead Acid Battery or Tubular battery. The terminal voltage of the battery is indicated through a four level LED indicators. The nominal terminal voltage of a Lead Acid battery is 13.8 volts and that of a Tubular battery is 14.8 volts when fully charged.

Simple LED Volt Meter Circuit Diagram

The LED voltmeter uses four Zener diodes to light the LEDs at the precise breakdown voltage of the Zener diodes. Usually the Zener diode requires 1.6 volts in excess than its prescribed value to reach the breakdown threshold level. When the battery holds 13.6 volts or more, all the Zener breakdown and all LEDs light up. When the battery is discharged below 10.6 volts, all the LEDs remain dark. So depending on the terminal voltage of the battery, LEDs light up one by one or turns off.

Electronic Torricelli Barometer

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Although it does not have the same charm as real mercury barometers with long glass tubes on pieces of carved and polished wood, the Torricelli barometer discussed here is a functional equivalent and electronic replica of the Torricelli barometer. Actually, rather than displaying the atmospheric pressure on the traditional digital displays, we preferred to reproduce the general look of this respected predecessor of electronic barometers.

The mercury tube is, of course, replaced by a simple LED scale which, if not as beautiful, is still less toxic for the environment in case of breakage. As indicated on the drawing, the pressure sensor utilized is a Motorola MPX2200AP. This circuit is adapted for measuring absolute pressure and has a range well suited for atmospheric pressure. Without entering too deep into the technical details, such sensors deliver an output of voltage proportional not only to the measured pressure but, unfortunately, to their supply voltage as well.

Hence they must be powered from a stable voltage which is ensured here by the use of IC1. Since the output of the MPX2200 is differential and at a very low level, we had to resort to the use of four operational amplifiers IC4.A to IC4.D, contained in one LM324, to obtain levels that can be processed easily. As long as potentiometer P1 is adjusted correctly, this group of operational amplifiers delivers a voltage of 1 volt per atmospheric pressure of 1,000 hPa to the LM3914.

Electronic Torricelli Barometer Circuit Diagram

Electronic Torricelli Barometer Circuit Diagram

Since the atmospheric pressure will be within the range 950 to 1040 hPa at sea level, we need to make an expanded-scale voltmeter with this LM3914 in order to better exploit the 10 LEDs that it can control. That is the role of resistors R7 and R8 which artificially raise the minimum voltage value the chip is capable of measuring. Consequently, we can ‘calibrate’ our LED scale with one LED per 10 hPa and thus benefit from a measurement range which extends from 950 hPa to 1040 hPa. In principle, you should not have a need to go beyond that in either direction.

The circuit may be conveniently powered from a 9-volt battery but only if used very occasionally. Since this is usually not the case for a barometer, we advise you to use a mains adaptor instead supplying approximately 9 volts. Calibration basically entails adjusting the potentiometer P1 to light the LED corresponding to the atmospheric pressure of your location at the time. Compare with an existing barometer or, even better, telephone the closest weather station. They will be happy to give you the information. After Evangelista Torricelli, 1608-1647, Italian physician who proved the existence of atmospheric pressure and invented the mercury barometer.

Eight LEDs Make a 100-Division Voltmeter

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The circuit in this Design Idea makes a voltmeter that reads to 0.99V. The idea uses a counter IC to drive two sets of four LEDs (Figure 1). Each of these two sets represents a BCD (binary-coded-decimal) value. With all of the LEDs off, the voltmeter reads 0V. With all of the LEDs on, the reading is 0.99V. Op amp IC1A generates a predictable voltage ramp.

Figure 1

You use op amp IC1B as a comparator to compare the ramp to an input signal. The higher the input voltage, the longer the output pulse from IC1B is. You use this pulse to gate free-running oscillator IC2B. A potentiometer on this multivibrator circuit allows you to adjust the full-range count. The voltmeter has a maximum input of 1V and uses three dual-part packages. You make output counter IC3 work as a two-digit counter by strapping the enable pin of the IC3B part to the MSB (most-significant-bit) output of the IC3A part.

A dual op amp is used to create the comparator function and the ramp generator. The design also uses a dual 555-type timer chip. You use IC2A to create the ramp and to reset it and the output counter, and you use IC2B as a free-running oscillator that drives the counter chip. To blank the output LEDs when the chip is counting, Q3 disables drive current to the LEDs when IC3 is incrementing. You use IC4 to derive a reference of 2.5V.

Figure 2

Eight LEDs Make a 100-Division Voltmeter

Tests of the design use TL084 op amps, but you can also use an LM358. A top view of the 15×15-hole prototype board shows component placement (Figure 2a). Figure 2b shows a bottom view of the board, with the connection and three resistors. You might use flat-green LEDs with the sides painted black or covered with black-plastic sleeves for good visibility. link

Simple SWR and PWR Meter

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Many SWR / Power meter used by amateurs to the extent reasonably accurate continuous average power with a CW key-down signal, but can not reliably be used with other (modulated) signals PEP or average power measurement. These laws seek to show why the power measurement can be a sensitive issue, and because the interpretation of a yardstick of power can be a lot of attention and knowledge of construction and the characteristics of the instrument.

A reflectometer-type SWR meter can be calibrated to give power back and forth (PF, Pr) on a power supply. A classic example is the 1943 Bird Series power meter, which is a directional coupler is used to obtain a sample voltage proportional to the voltage wave or forward or backward on the feeder (VF, VR). Other systems, perhaps more suitable for HF, then use a bridge circuit to perform the same function.

Simple SWR and PWR Meter Circuit diagram

The sample voltage is then rectified and displayed on a meter that is calibrated in watts. If the counter is typically a coil, the scale, so the numbers on the scale, representing the power, are proportional to the square of the applied voltage or the current calibration. The theory of this type is very simple and is based on the concept represented by PF = Vf2/Zo. Note that if the power supply has an impedance that differs from the value of how the instrument is calibrated, there will be a mistake. The output voltage of the rectifier is a solid phase of VF or VR, and this is expected in the calibration of the meter.

Examples of directional coupling, and bridge-type reflectometers are shown in Figures 1 and 2, while the bird directional coupler means 43 is illustrated in Figure 3. Note that in all cases the measurement circuit, a combination with a small RC time constant, making the system unsuitable for the measurement of PEP, and the absence of a specific device quadratic, making them unsuitable for measuring the average power .