3 bedroom houses for sale east dunbartonshire

# Rc circuit applications

.

girl telegram group link 2022

Resistor-Capacitor combination is commonly used in filters some of the applications of the RC circuit are listed in the following: RC circuit is used as the low pass filter. RC circuit can also be used as the high pass filter. RC circuit can be used in.

uil marching band practice rules

bexar county young democrats

chevy 235 hydraulic lifter adjustment

Frequency Response of a Circuit Example A series RC low-pass filter cutoff frequency is 8KHz. R=10KΩFind the capacitor value 1 c RC ω= 1 c C ωR = 1 1.99 2* *8000 10000 CnF π x == Example A series RL low-pass filter cutoff frequency is.

compound monthly growth rate calculator

• Grow online traffic.
• Nurture and convert customers.
• Keep current customers engaged.
• Differentiate you from other similar businesses.
• Grow demand and interest in your products or services.

hwy 212 construction

vw misfire at idle

An RC circuit is an extremely common circuit configuration, one that you can find by itself or, more frequently, as part of a bigger circuit. Also, sometimes RC circuits are unintentional and simply parasitic in nature. With this RC calculator, you can get an intuitive understanding of what happens with a charging and discharging RC circuit in.

what to do if a child makes an allegation

The formula to calculate the frequency of RC circuit is. Let us consider a R-C High-Pass-Filter which is built with generator, a 10nF Ceramic Capacitor and a 10KΩ Resistor. Now let us calculate the frequency based on the above circuit example. = 15,923 Hz. Hence, the RC circuit will pass the frequencies above 15,923 Hz.

milan mo tractor pull

## john deere gator 625i throttle body

The formula to calculate the frequency of RC circuit is. Let us consider a R-C High-Pass-Filter which is built with generator, a 10nF Ceramic Capacitor and a 10KΩ Resistor. Now let us calculate the frequency based on the above circuit.

What are the applications of RC circuits They are used in traffic lights RC circuits are used in pacemaker It can be used in audio equipment RC circuits can be used in places were signal filtering is needed It can be used as an integrator or differentiator.

The time constant in an RLC circuit is basically equal to 𝛽, but the real transient response in these systems depends on the relationship between 𝛽 and 𝜔0. Second-order systems, like RLC circuits, are damped oscillators with well-defined limit cycles, so they exhibit damped oscillations in their transient response.

In many applications, these circuits respond to a sudden change in an input: for example, a switch opening or closing, or a digital input switching from low to high. Just after the ... The time constant is ˝= RC, where Ris the resistance seen by the capacitor. To nd this, we short (zero) the voltage source and imagine measuring the resistance.

V- VR + VL = 0. The voltage drop across inductor and resistor is given by. VR = I × R and VL= L (di/dt) So, the RL circuit formula is given by. V = I × R + VL= L (di/dt) With the above equation, it can be stated that VR is based on the current 'i', whereas VL is based on the rate of change in current.

EECE 2150 - Circuits and Signals: Biomedical Applications Lab 9 Introduction to RC Circuits in the Time and Frequency Domains Part 1. Transient Signals with an RC Circuit with Square Waves Figure 1. Simple RC circuit for Part 1. figure 1. Set your function generator to produce a 1 V amplitude square wave to charge and.

70 percent va disability 2022

In this lab activity you will apply a pulse waveform to the RC circuit to analyse the transient response of the circuit. The pulse-width relative to a circuit's time constant determines how it is affected by an RC circuit. Time Constant (τ):.

veronica garcia

The formula to calculate the frequency of RC circuit is. Let us consider a R-C High-Pass-Filter which is built with generator, a 10nF Ceramic Capacitor and a 10KΩ Resistor. Now let us calculate the frequency based on the above circuit example. = 15,923 Hz. Hence, the RC circuit will pass the frequencies above 15,923 Hz.

This app is used to calculate the RC charging circuit and RC filter. It is suitable for hobbyist or electronic engineers. Features: 1. Calculate time constant by R and C. 2. Calculate between time constant and % of charging. 3. Calculate cutoff frequency of low-pass filter/ high-pass filter by resistor and capacitor values.

vermont state representatives

EasyEDA online circuit simulator. EasyEDA is a free, zero-install, web and cloud-based EDA tool suite which integrates powerful schematic capture, mixed-mode circuit simulator and PCB layout in a cross-platform browser environment, for electronic engineers, educators, students, and hobbyists.. As EasyEDA is completely free, super easy to use, and feature-rich,.

what happens when a guy loses a good girl

The RC circuit is used in camera flashes, pacemaker, timing circuit etc. The RC signal filters the signals by blocking some frequencies and allowing others to pass through it. It is also called first-order RC circuit and is used to filter the signals bypassing some frequencies and blocking others.

To debounce the button circuit properly, we cannot use a capacitor alone; we must use a resistor as well. The combination of a resistor and capacitor in this circuit is referred to as an RC filter.RC filters can be used to filter out different frequencies of electrical variation. A properly designed RC filter could be be used to filter out specific sound frequencies (represented as.

A differentiating circuit is a simple RC series circuit with output taken across the resistor R. The circuit is designed in such a way that output is proportional to the derivative of the input. Thus if a d.c. or constant input is applied to such a circuit, the output will be zero. It is because the derivative of the constant is zero.

The circuit is built by using electrical linear elements. The circuit is designed to provide a cut off frequency of 4 GHz. The example file is rc_circuit.icp. Fig 1. RC filter circuit. Circuits with elements that support ‘Electrical Node’ ports should be built as a sub-circuit using a Compound Element. The Compound Element scattering data.

raidforums backup

• A pest control company can provide information about local pests and the DIY solutions for battling these pests while keeping safety from chemicals in mind.
• An apparel company can post weekly or monthly style predictions and outfit tips per season.
• A tax consultant’s business could benefit from the expected and considerable upturn in tax-related searches at certain times during the year and provide keyword-optimized tax advice (see the Google Trends screenshot below for the phrase “tax help”).

houses for sale fintona

Applications: It is used in the initial stages of public address (PA) amplifier systems. It is used in stereo amplifier. It is widely used as a voltages amplifier. It is used in tape recorder, CD players, VCRs, DVD players, etc. It is used in radio and television receivers.

black decker pole saw

The Colpitts oscillator is a type of LC oscillator, invented by Scientist Edwin Colpitts in 1918. Its tank circuit comprises an inductor and two capacitors. The capacitors have a series connection, whereas the inductor has a parallel connection to the capacitor series. Its operating range is approximately 20KHz to MHz.

Time-delay Circuit Applications. Time delay circuits provide numerous benefits with their delay capabilities. We outlined some example applications of time delay circuits below. ... As we learned, a time-delay circuit utilizes an RC network to store and distribute power, contributing to the delayed effect. Therefore, this can occur anywhere.

Snubber Considerations for IGBT Applications by Yi Zhang, Saed Sobhani, Rahul Chokhawala International Rectifier Applications Engineering 233 Kansas St., El Segundo, CA, 90245 USA Abstract - Snubber circuits can be used to protect fast switching IGBTs from turn-on and turn-off voltage transients. Snubbers are available in various. 6. Application: Series RC Circuit. An RC series circuit. In this section we see how to solve the differential equation arising from a circuit consisting of a resistor and a capacitor. (See the related section Series RL Circuit in the previous section.) In an RC circuit, the capacitor stores energy between a pair of plates.

### matlab subplot size

Determining the time constant of the RC circuit has important practical applications because, for example, it can be used to measure unknown values of resistance or capacitance. The transient experiment can be done by using a voltmeter and stopwatch, signal generator and oscilloscope, or even low-cost data acquisition systems such as Arduino..

Chapter 1 is an introduction to second order circuits and it is essentially a sequel to first order circuits that were discussed in the last chapter of as Circuit Analysis I with MATLAB® Applications . Chapter 2 is devoted to resonance, and Chapter 3 presents practical methods of expressing signals in terms of.

Some applications of. ... RC CIRCUIT: From equition 1 and 3 and Kirchhoff’s voltage law we get, RI+=E(t) R+I= += The above equation’s solution also can be find out by LDE method. RL CIRCUIT PROBLERM: Q. A series RL circuit with R=50Ω and L=10H has a constant voltage V=100V at t=0. After closure of switch find current in the circuit at t=0. Download RC Circuit Pro and enjoy it on your iPhone, iPad, and iPod touch. ‎This app is used to calculate the RC charging and RC filter circuit. It is suitable for hobbyist or electronic engineer. Features * Calculate time constant from R, C * Find component value R,C from time constant * Get voltage at time t in RC charging / discharging.

The solution for this differential equation is. q = q_ {max} (e^ {\frac {-t} {RC}}). q = qmax(eRC−t). Again, RC \rightarrow RC → is called the time constant of the circuit, and is generally denoted by the Greek letter \tau. τ. Hence the complete equation that gives us the charge on the capacitor at any time t t is.

top surgeons in uk

## cvs skin glue

March 01, 2012. Thanks! The LED/photodiode symbols do show little arrows corresponding to photons emitted / received. However, their physical placement on the schematic doesn't imply any actual connection between them, so there's no photocurrent running through the photodiode. You could model that by adding a CCCS (Current-controlled current.

used boats for sale in md

resistor for the circuit. In other words, the resistor in the 850 Universal Interface is the R in the RC circuit. The internal resistor is given as R i= 1 M. Use the Capstone software to set up a dispaly containing a two column table, and select voltage in the rst column, and time in the second column. Then nd the.

0. Well a Capacitor is basically open circuit for DC. So here the capacitor will just be open circuit and will not affect the circuit. The circuit should essentially behave like a resistor in series with a battery. However if initially the C is not charged, then it will be a short and a large current will flow through it for a short time.

V- VR + VL = 0. The voltage drop across inductor and resistor is given by. VR = I × R and VL= L (di/dt) So, the RL circuit formula is given by. V = I × R + VL= L (di/dt) With the above equation, it can be stated that VR is based on the current ‘i’, whereas VL is based on the rate of change in current.

Circuit Description The schematic of the absolute circuit is shown in Figure 3. The state-variable oscillator consists of two integrators and an inverter circuit. Each integrator pro-vides a phase shift of 90°, while the inverter adds an additional 180° phase shift. The total phase shift of 360° of the feedback loop produced by the three ampli-.

Definition: Clipper circuits are the circuits that clip off or removes a portion of an input signal, without causing any distortion to the remaining part of the waveform.These are also known as clippers, clipping circuits, limiters, slicers etc. Clippers are basically wave shaping circuits that control the shape of an output waveform. It consists of linear and non-linear elements but does.

obd protocol pdf

21 blitz promo code free money 2022

dragon papercraft pdf

4 lepers in the bible

Read this page to know what the applications of RC and RL circuits are. ... The RC circuits are used in the timing circuit, camera flashes, pacemaker etc. The RC and RL circuits are used to filter certain frequencies and it allows certain frequencies, waveshaping and timing.

• The circuit used to couple sound into your Arduinois a simple RC circuit. • This circuit provides a DC voltage of V dd/2 at the output. • For AC (sound) signals, the capacitor will block low frequencies but pass high frequencies. (High pass filter). • For AC signals, the two resistors are in parallel, so the equivalent circuit is shown on.

### best electronic components companies in india

NE555 and NE556 applications AN170 1988 Dec 2 INTRODUCTION In mid 1972, Philips Semiconductors introduced the 555 timer , a ... circuits into the ever increasing ranks of timer users. ... threshold pin normally monitors the capacitor voltage of the RC timing network. When the FLIP FLOP COMP COMP 555 OR 1/2 556 DISCHARGE CONTROL VOLTAGE.

Timer Circuits Modification of Timing Networks The monostable multivibrator circuits you studied in a pre­ vious lesson required an RC timing network for their opera­ tion. If you want circuits to be used over a wide range of applications, however, you must be able to switch the timing network to produce new RC time-constant values.

The circuit is simple and cost-effective as it is a transformerless driver. Limitations of 230 Volts LED Driver Circuit. This circuit can be dangerous as 230 volts AC mains supply is directly used here. For single-phase supply generally.

Series Resonance. The resonance of a series RLC circuit occurs when the inductive and capacitive reactances are equal in magnitude but cancel each other because they are 180 degrees apart in phase.The sharp minimum in impedance which occurs is useful in tuning applications. The sharpness of the minimum depends on the value of R and is characterized.

. Chapter 10: Op-amp circuits for detectors, filters, and power applications. Chapter 10: Op-amp circuits for detectors, filters, and power applications. We can improve the performance of most of the circuits we have built in this course, including RC circuits and rectifiers, by using op amps and negative feedback. I. Active Filters.

quercetin and cymbalta

The formula to calculate the frequency of RC circuit is. Let us consider a R-C High-Pass-Filter which is built with generator, a 10nF Ceramic Capacitor and a 10KΩ Resistor. Now let us calculate the frequency based on the above circuit example. = 15,923 Hz. Hence, the RC circuit will pass the frequencies above 15,923 Hz.

fume vape orjoy

The inductor is a circuit or a device component that exhibits self-inductance. However, since there is a presence of a resistor in the ideal form of the circuit, an RL circuit will consume energy, akin to an RC circuit or RLC circuit. Consider the above circuit having a battery, a resistor, and a switch.

## pwc sustainability internship

The circuit diagram of an RC Triggering is shown below (Figure 2). Figure 2 shows an R-C-Diode circuit giving full half-cycle control (180 electrical degrees). On the positive half-cycle of SCR anode voltage the capacitor charges to the trigger point of the SCR in a time determined by the RC time constant and the rising anode voltage. The top.

But 4 RC segments enhance cost and makes circuit complexity. Hence phase shift oscillators make use of 3 RC sections and in that each section gives a phase shift of 60 degree. The latter 3 RC networks are generally used in high precision applications where cost is not much considered and only accuracy plays a major role. Conclusion.

on active RC networks and one on op amp applications. These old publications, from 1966 and 1963, respectively, are some of the finest works on op amp theory that I have ... Stable Natural Frequencies for Active RC Circuits There are several types of active elements that can be used in active RC networks. First, there.

arbys specials this week

A differentiating circuit is a simple series RC circuit where the output is taken across the resistor R. The circuit is suitably designed so that the output is proportional to the derivative of the input. Thus if a d.c. or constant input is applied to such a circuit, the output will be zero. Fig.1 shows a typical differentiating circuit.

This circuit is one transistor gyrator circuit which can be easily adjusted to simulate different inductance coils just by changing the value of capacitor C2. The value of inductance the circuit simulates is approximally simulates has value of 1 henry for every 2 microfarads in C2. So if you want to make 5 henry coil simulator, you just use 10. An RL circuit (sometimes called an RL filter or RL network) is an electrical circuit made up of the passive circuit elements of a resistor (R) and an inductor (L) linked together and driven by a voltage or current source. An RL circuit, like an RC or RLC circuit, will consume energy due to the inclusion of a resistor in the ideal version of the.

motorola 2 way radio programming software

vines creek marina slip rates

The fundamental passive linear circuit elements are the resistor (R), capacitor (C) and inductor (L) or coil. These circuit elements can be combined to form an electrical circuit in four distinct ways: the RC circuit, the RL circuit, the LC circuit and the RLC circuit with the abbreviations indicating which components are used. RC and RL are one of the most basics.

This RLC circuit [Figure 1] proved to be an interesting demonstration of the current in a circuit without a voltage source. The initial current running through the circuit is provided by the charged capacitor. However, this initial current undergoes damping due to the resistor in place, and the current running through the circuit pretty. Applications for RC circuits include: Filtration (Most common use as a high pass or low pass basic filter for AC wave forms.), DC logic circuits use them for hardware debouncing (not very common as debouncing is better with a pulldown or pull up resistor), Spike generators for one time switches and latches, and wave form modulation from square (Think PWM) to saw (which.

### aldi pebbles

This RC circuit will provide a low frequency path to the input of the amplifier. The amplifier acts as a buffer circuit providing unity gain output. This circuit has more input impedance value. ... Applications Of Active Low Pass Filters. In electronics these filters are widely used in many applications. These filters are used as hiss filters.

This circuit is one transistor gyrator circuit which can be easily adjusted to simulate different inductance coils just by changing the value of capacitor C2. The value of inductance the circuit simulates is approximally simulates has value of 1 henry for every 2 microfarads in C2. So if you want to make 5 henry coil simulator, you just use 10.

An RC circuit is a circuit with both a resistor (R) and a capacitor (C). They are a common element in electronic devices and play an important role in the transmission of electrical signals. RC circuits are used as audio filters, electronic timers, oscillators, and more in a wide range of electronics project. How RC Circuits Work.

applications and one on active RC networks. These old publications, from 1963 and 1966, respectively, are some of the finest works on op amp theory that I have ever seen. ... modules instead of integrated circuits. Many references to these numbers were made in the text, and these have been changed, of course.

squeezed pimple after botox

## injectable sr9009 uk

In this lab activity you will apply a pulse waveform to the RC circuit to analyse the transient response of the circuit. The pulse-width relative to a circuit's time constant determines how it is affected by an RC circuit. Time Constant (τ):.

areas of improvement performance review examples

RC and RL Circuits Rules to remember •ELI the ICE man: Voltage (E) leads Current (I) in an Inductive (L) circuit , whereas Current (I) leads Voltage (E) in a Capacitive (C) circuit –This is only true for SERIES circuits. When it goes into a parallel configuration, the opposite occurs •Current leads Voltage in a Parallel Inductive circuit.

This RC circuit calculator will calculate the maximum current I max at the beginning of the capacitor charging, the maximum energy E max and maximum charge Q max in the capacitor when it is fully charged, for the given voltage across it as well as the time constant τ in the RC circuit.. Example: Calculate the time constant, max. energy, max. current and max. charge for an RC circuit.

An RC circuit is an extremely common circuit configuration, one that you can find by itself or, more frequently, as part of a bigger circuit. Also, sometimes RC circuits are unintentional and simply parasitic in nature. With this RC calculator, you can get an intuitive understanding of what happens with a charging and discharging RC circuit in.

Hello! I'm trying to make an RC circuit on which the charge and discharge of the capacitor is cyclic, so it can later be used as a model for a pacemaker. With the code below, I use a control sistem to make the charge of the capacitor never be over 0.50V and used a state machine to create the cycle on which it charges and discharges at the same rate. I'm also using two transistors 2n2222 to.

• Model: RC circuit ! differential equation for V out(t) • Derivation of solution for V out(t) ! propagation delay formula EE16B, Fall 2015 Meet the Guest Lecturer Prof. Tsu-Jae King Liu • Joined UCB EECS faculty in 1996 • Courses taught: 40, 105, 130, 143, 290D, 375.

## gypsy england 1920

dutch reformed church beliefs

list of texas ghost towns

This can be verified using the simulator by creating the above mentioned parallel RC circuit and by measuring the current and voltage across the resistor and capacitor. It should be consistent with the earlier findings. Applications: It can be used as. 1. Oscillators. 2. RC filter calculator. 3. Voltage dividing circuit. 4. Coupling and wave.

filing cabinets for home

‎This app is used to calculate the RC charging and RC filter circuit. It is suitable for hobbyist or electronic engineer. Features * Calculate time constant from R, C * Find component value R,C from time constant * Get voltage at time t in RC charging / discharging *.

The RL and RC circuit are the backbone of various electronic circuits. Both of these has its advantages and disadvantages; it depends on the application that which circuit is to be used. If you are dealing with low power application, then RC circuit is appropriate as it is of low cost.

Figure 2: Capacitor charging for Series RC circuit to a step input with time axis normalised by t The discharge voltage for the capacitor is given by: V C (t) = V o e-t/RC t ‡ 0 (4) Where V o is the initial voltage stored in capacitor at t = 0, and RC = t is time constant. The response curve is a decaying exponentials as shown in Figure 3..

drive medical authorized repair

• Invites to industry events (such as Pubcon within the digital marketing world).
• Even entire buyouts of companies.

## blackpink photoshoot

penguin character

International Journal of Circuit Theory and Applications. Volume 45, Issue 11 p. 1514-1533. Research Article. Electrical circuits RC, LC, and RL described by Atangana–Baleanu fractional derivatives. ... In this paper, the analytical solutions for the electrical series circuits RC, LC, and RL using novel fractional derivatives of type Atangana.

international loadstar 1700 specs

bands like sleep

Transient Response of Second Order Circuits 22 Circuits with Non-linear Elements; Diode 23 Design and Analysis of Diode Circuits 24 BJT 25 BJT (cont.) 26 BJT (cont.) 27 Quiz 3 28 Op Amp 29 Op Amp (cont.); Fundamental Amplifier Circuits; Input/Output Impedance 30 Op Amp (cont.); Active Filters; Superdiode, Log.

Passive Low Pass Filter. Low pass is a circuit whose are made of resistance “R”, capacitor “C” and inductor “L”. When we use RL than it is called RL filter and when we use RC than it is called RC filter. The function of low pass filter is to reject all higher frequency and pass low frequency. The range of low frequency is 0-100 kHz.

RC circuits are widely used in analog circuits and pulse digital circuits. If a RC parallel circuit connected in series in the circuit, it can attenuate low-frequency signals, and if it connected in parallel in the circuit, it can attenuate high-frequency signals. That is filtering. RC circuit is common element in electronic devices.

## does united healthcare cover vasectomy reversal

The time constant for this circuit is passed. After one time constant, the voltage, charge, and current have all decreased by a factor of e. After two time constants, everything has fallen by e2. The initial current is 1A. So after two time constants, the current is 1/e2 A = 0.135A. C=0.1F R=10Ω More complex RC circuit: Charging C with a battery.

seatrax email

Simple circuit design tutorial for PoE applications. As the number of Power Over Ethernet (PoE) powered device (PD) applications grows, market pressures are driving designers to lower the cost and complexity of the DC-DC converters that power them, while improving their performance. This paper provides simple circuit designs that meet those goals.

The first order active LPC circuit is designed with a capacitor, resistor, and an op-amp as shown below. The inverting or non-inverting op-amp is connected to the RC circuit to obtain an active LPF circuit. The amplitude output signal obtained from the RC low pass filter circuit is smaller than the amplitude of the input signal.

Read this page to know what the applications of RC and RL circuits are. ... The RC circuits are used in the timing circuit, camera flashes, pacemaker etc. The RC and RL circuits are used to filter certain frequencies and it allows certain frequencies, waveshaping and timing.

rammstein crew

van saar weapon pack 2

inexpensive baby shower venues near krasnoyarsk

wow ground target macro

west jordan parks and recreation

raffle ticket books 11000

all inclusive beach resort
short projection back to wall toilet 480mm
extra large plastic plant trays

## esp8266 battery board

hotmail smtp settings for printer

An audio crossover circuit consisting of three LC circuits, each tuned to a different natural frequency is shown to the right. The inductors ( L) are on the top of the circuit and the capacitors ( C) are on the bottom. On the left a "woofer" circuit tuned to a low audio frequency, on the right a "tweeter" circuit tuned to a high audio frequency.

### onlyfans apk hack 2022 android

The RC circuit has thousands of uses and is a very important circuit to study. Not only can it be used to time circuits, it can also be used to filter out unwanted frequencies in a circuit and used in power supplies, like the one for your computer, to help turn ac voltage to dc voltage. Figure 1. Typical RC Circuit (DC, AC, and Pulse Signals.

swag mode premium script free
By clicking the "SUBSCRIBE" button, I agree and accept the portrait photography locations london and bmw e34 540i for sale uk of Search Engine Journal. hedgehog farm near me
kyle busch joe gibbs
sample encroachment letter
used packing boxes near Sardarshahar Rajasthan  • Enroll for Free. This course is all about differential equations. Both basic theory and applications are taught. In the first five weeks we will learn about ordinary differential equations, and in the final week, partial differential equations. The course contains 56 short lecture videos, with a few problems to solve after each lecture.
• RC circuits can be used to filter a signal by blocking certain frequencies and passing others. The two most common RC filters are the high-pass filters and low-pass filters; band-pass filters and band-stop filters usually require RLC filters, though crude ones can be made with RC filters. Contents 1 Introduction 2 Natural response
• Electronics Fundamentals: Circuits, Devices &amp; Applications. Show all chapter solutionsadd. Ch. 10 ... In a series RC circuit the voltage across the capacitor and the resistor are 60 volts and 80 volts respectively. The total voltage is. arrow_forward. Compute the impedance of a series RL circuit with the following values: R = 114 ΩL = 347 ...
• The RC Circuit Circuits containing both resistors and capacitors have many useful applications. Often RC circuits are used to control timing. Some examples include windshield wipers, strobe lights, and flashbulbs in a camera, some pacemakers. One could also use the RC circuit as a simplified model of the transmission of
• Some applications of. ... RC CIRCUIT: From equition 1 and 3 and Kirchhoff’s voltage law we get, RI+=E(t) R+I= += The above equation’s solution also can be find out by LDE method. RL CIRCUIT PROBLERM: Q. A series RL circuit with R=50Ω and L=10H has a constant voltage V=100V at t=0. After closure of switch find current in the circuit at t=0 ...