A simple passive logarithmic VU meter. Introduction. A VU meter is a very common instrument usually installed on audio Hi Fi. It is usually connected at the output of the amplifier, in parallel with. The term VU stands for Volume Unit and should be defined with. VU being equal to 4 d. Vu Meters Software' title='Vu Meters Software' />Bm, or 1. RMS across a. VU is often referred to as 0 d. B and volume units are. In consumer electronics amplifiers this standard is rarely met and the meters. Anyway, the only thing one probably wants to know is how much power the. So a meter that gives a reading between zero and the maximum power output is. Stardust is a powerful 4in1 mastering plugin. Bass enhancement around selected bass frequency, Q and gain control 200Hz switchable pole phase rotator off, 2, 4. Technical description. Analogue S meters are actually sensitive microammeters, with a full scale deflection of 50 to 100 A. In AM receivers, the S meter can be. Products. Our goal is to provide to you the best audio tools with the most effective user interface. Explore the far reaches of the world, right in your browser. A peak programme meter PPM is an instrument used in professional audio to indicate the level of an audio signal. There are many different kinds of PPM. The audio volume is often expressed using a logarithmic scale because the. Watts would not be very representative of the. Vu Meters Software' title='Vu Meters Software' />Results. The z score for the bodymass index BMI, the weight in kilograms divided by the square of the height in meters increased on average by 0. SD units in the. For example, a few millivolts on an 8  speaker are clearly. When listening at low volume, the voltage on the speakers is only a few. When the volume is raised to a medium setting, the voltage on the speaker is. Watt and only when the volume is. Non professional audio amplifiers often have simple and useless VU meters. Vu Meters Software' title='Vu Meters Software' />For example, the circuit diagram shown in the figure below was found in my. WRMS on 8  and is composed. C1, D1 and D2. a filter capacitor C2 and a microammeter M1. The full scale is adjusted via R1 to match the maximum power output of the. Solid state voice recorders can replace awkward, unreliable tape systems in voice record and playback applications. Applications include message storage, crowd. Deja Vu Skin Care Products Homeopathic Skin Tag Removal Deja Vu Skin Care Products Best Vegan Skin Care Products Best Facial Wrinkle Creams. Music Making DAW Software Accessible for Blind and Visually Impaired Audio Engineers and Musicians. UjgiGRPAok/0.jpg' alt='Vu Meters Software' title='Vu Meters Software' />But with this simple circuit, the reading is proportional to the peak output. So the amplifier has two nice meters that almost never move. Furthermore, the use of a voltage doubler is very surprising and a bad. V while germanium or Schottky. In this configuration, any signal lower than 1. Vpeak has no. chance of moving the meter. So this diagram has a big red cross its a bad idea, dont use it. In order to have meaningful readings, the meter should be logarithmic. Professional or high end amplifiers have good meters with logarithmic. VU meter with only a few parts. And useless linear meters like the one just described can easily be converted. A simple circuit. The basic idea is to use the logarithmic characteristic of diodes to obtain a. The circuit is shown below and is really very simple. Its based on a standard 2. A microammeter which is very very. Its internal resistance is not critical at all and is usually between. The circuit is intended to fit an amplifier capable of 8. WRMS. driving a 8  load, but can easily be adapted to other power levels. Similar power levels requires no modification, for much higher. R4 must be modified and maybe also R2 and R3. First the AC signal across the speaker is rectified by diode D1. D1 should be a germanium diode or a Shottky diode to minimize the voltage. Google Sketchup 8 Portable more. Every millivolt lost here will reduce the sensitivity at low volume. But D1 has to stand twice the peak voltage of the speaker, so the reverse. For example, 8. 0 W over 8  have a voltage of. W  8    2. 5. 3 VRMS. V  3. 5. 8 Vpeak. V  7. 1. 6 V on its leads. Germanium diodes have a low voltage drop, about 0. V, but the. majority of them have breakdown voltages between 3. V Small signal Schottky diodes can have voltage drops in the 0. V. range depending on the model and can easily deal with reverse voltages up to. Dont use high current Schottky diodes or silicon diodes because their. V range and is too high for this. Resistor R1 is a very good idea because it increases the impedance of the. Otherwise, connecting a rectifier in parallel with a speaker could introduce. The 1. 0 k of R1 are high enough compared to the. R1 will also limit the current in D1 if the maximum diode reverse voltage is. Capacitor C1 integrates the rectified signal and provides only DC to the. The time constant is below 5. Now the tricky part for low voltages, D2, D3 and D4 do not conduct. These are regular small signal silicon diodes with a forward drop of. V here a high voltage drop is important. So for low voltages D2, D3, D4, R2 and R3 can be neglected and the current. This can be observed in the graph below the one on the left for input. V, the current in the meter blue trace is linear. D2 green trace and D3 D4 yellow trace conduct no current. As soon as the voltage rises, D2 starts conducting and robs current to the. On the same graph, above 0. V the current in D2 green trace starts. For even higher voltages about 1. V, graph on the right, D3 and D4. The effect is that the meter current slope blue trace is further reduced. To calculate this circuit especially the values of R2 and R3, the common. V threshold voltage is not enough. One has to use the diode characteristic exponential function, but equations. I wasnt able to solve it with just a pencil and a piece. Fortunately, free SPICE software is available and the circuit can easily be. The figure below shows in blue the response of this circuit and compares it. As one can see, the performance of such a simple circuit is pretty good. Probably, spending more time with a simulator, one could achieve an even. I decided it was good enough for me. Trimmer R4 is used to set the full scale of the meter. The easiest way to adjust it is, before connecting this circuit to your. DC source to the input corresponding to the maximum peak voltage. V in this case and turn it in the other direction to align the. Because of the logarithmic characteristic of this circuit, the correct. R4 is not critical at all. Another way to adjust R4 is to install the circuit at the output of the. The problem with this second method is that the speaker must be connected. Of course, you could replace the speaker with a suitable dummy load, if you. In this way, the meter will read the output power of the amplifier and not. VU units, and I think this is the most useful reading. If you prefer real VU units or d. Bm units, you can still apply the same. If not adjusting for full scale at full power, verify that the needle wont. Please remark that the type of rectifier used in this circuit requires a DC. This is usually not a problem tube amplifiers have transformer output that. DC, push pull amplifier with dual power supply are DC coupled as. Single supply transistor amplifiers, on the other hand, have a capacitor. DC path does not exist in the amplifier. But a DC path always exists in the speaker and as long as the speaker is. VU meter will work fine. Dont worry about this DC current, because of the high value R1, its value. One of the big advantages of this simple circuit is that its completely. This means it can be connected directly in parallel with the amplifier output. No matter if its a push pull, a single ended, an H bridge, a transformer. There is no risk of shorting to ground half of the output transistors or. A simple circuit to build a simple logarithmic VU meter has been presented. Its simplicity really outperforms common linear VU meters for about the same. Even if its accuracy is lower than what is achieved with professional. Hi Fi amplifier of a stereo set. Furthermore, this circuit is completely passive, requires no power supply. S meter Wikipedia. Not to be confused with Field strength meter,nor with S units used in mathematics. S Meter of a Ten Tec Orion amateur radio transceiver. An S meter signal strength meter is an indicator often provided on communications receivers, such as amateur radio receivers or shortwave broadcast receivers. The scale markings are derived from a system of reporting signal strength from S1 to S9 as part of the R S T system. The term S unit can be used to refer to the amount of signal strength required to move an S meter indication from one marking to the next. Technical descriptioneditAnalogue S meters are actually sensitive microammeters, with a full scale deflection of 5. A. In AM receivers, the S meter can be connected to the main detector or use a separate detector at the final IF stage. This is the preferred method for CW and SSB receivers. Another approach in the days of electronic tubes valves was to connect the S meter to the screen grid circuit of the final IF amplifier tube. A third option is to connect the S meter to the AGC line through a suitable level conversion circuit. In FM receivers, the S meter circuit must be connected to the IF chain before any limiter stages. Some specialized integrated circuits for FM reception like CA3. CA3. 18. 9 provide a DC signal to drive a 1. A S meter. 2In most consumer grade desktop tube receivers and in some military receivers the S meter was replaced with a magic eye tube. IARU Region 1 Technical Recommendation R. LCD emulation of an S meter on the Ten Tec Jupiter tranceiver. In the 1. 93. 0s it was already agreed that S9 corresponds to 5. V at the input terminal of the receiver,34 but this was not a measure of the power received as the input impedance of receivers was not standardized. The International Amateur Radio Union IARU Region 1 agreed on a technical recommendation for S Meter calibration for HF and VHFUHF transceivers in 1. IARU Region 1 Technical Recommendation R. S9 for the HF bands to be a receiver input power of 7. Bm. This is a level of 5. For VHF bands the recommendation defines S9 to be a receiver input power of 9. Bm. This is the equivalent of 5 microvolts in 5. The recommendation defines a difference of one S unit corresponds to a difference of 6 decibels d. B, equivalent to a voltage ratio of two, or power ratio of four. Signals stronger than S9 are given with an additional d. B rating, thus S9 2. B, or, verbally, 2. S9, or simply 2. ExampleseditA weak signal with signal strength of S2 corresponds to received power of 1. Bm or 0. 4. 0 microvolts RMS in 5. HF. A strong signal with signal strength of S8 corresponds to received power of 7. Bm or 2. 5 microvolts RMS in 5. HF. Some signal generators are calibrated in d. B above 1u. V and have an output in emf. For example to set an HF receivers S reading to S9 set the signal generator output to 3. B above 1u. VS reading. HFSignal Generator emfV rms, Relative to 5. Bmd. B above 1u. VS91. B1. 60. 0 6. 34. S9. S8. 25. 1 7. 92. S7. S6. 6. 3 9. 11. 6S5. S4. 1. 6 1. 03. 4S3. S2. 0. 4 1. 15 8. S1. 0. 2 1. 21 1. AccuracyeditMost S meters on traditional analog receivers are not calibrated and in practice can only provide a relative measure of signal strength based on the receivers AGC voltage. Some S meters on traditional analog receivers are calibrated to read S9 for an input of 7. Bm but do not provide the correct 6 d. B per S unit correspondence. Often the correlation between a radio listeners qualitative impression of signal strength and the actual strength of the received signal on an analog receiver is poor, because the receivers AGC holds the audio output fairly constant despite changes in input signal strength. SDRs Software Defined Radios acquire and process signals differently, and determine S readings by direct measurement of RF signal amplitude. Consequently, many SDR systems with bit depths of 1. S scale to the other right out of the box. In cases where this is not so, a few minutes with a signal generator to set the reference level are all that is required. Low bit depth SDRs such as an 8 bit design can be somewhat accurate, but as they distinguish much coarser differences in input levels, precision at the low end of the S scale will suffer. Even with a high quality SDR, it is worth keeping in mind that the S meter is measuring the strength of the signal at the 5. For example, if the radios input is 5. Many antennas vary in impedance over various frequency ranges, particularly in the case of wideband designs. What is useful to know is that the relative signal strengths at any one frequency will remain meaningful, even if they are not from one frequency to another. See alsoeditReferenceseditTony Dorbuck, K1. FM, ed. 1. 97. 8. The Radio Amateurs Handbook. Newington, CT American Radio Relay League. G. R. Jessop, G6. JP 1. 98. 3. VHF UHF manual 4th ed. Potters Bar, UK Radio Society of Great Britain. ISBN 0 9. 00. 61. Introduction manual to the National HRO. Malden, Mass National Company, Inc. Tony Dorbuck, K1. FM, ed. 1. 97. 8. The Radio Amateurs Handbook. Newington, CT American Radio Relay League. International Amateur Radio Union Region I 1. IARU Region 1 Technical Recommendation R. Brighton, England, UK. Michael Kastelic, OE1. MCU, ed. 2. 01. 0. Pdf Split And Merge Ubuntu. VHF Managers Handbook, Version 5. International Amateur Radio Union Region 1. Further readingeditExternal linksedit.