Electronics Projects, PIC16F628 LC meter circuit article " microchip projects, microcontroller projects, pic assembly example, pic16f628 projects, " tagged with
LC meter circuit made with 16F628 microcontroller can be used to measure the inductor and capacitor values.
Despite its modest cost, it offers automatic direct digital measurement over a wide range for both capacitance (C) and inductance (L) with 4-digit resolution. In fact, it measures capacitance from just 0.1pF up to 800nF and inductance from 10nH to 70mH. Measurement accuracy is also surprisingly good, at better than ±1% of reading
It also operates from 9-12V DC, drawing an average current of less than 20mA. This means that it can be powered from either a 9V alkaline battery inside the case or from an external plugpack supplyLCD Display LC meter circuit
LC meter circuit PCB schematic pic16f628 pic assembly source code alternative link: pic16f628-lc-meter-circuit.RAR alternative link2 alternative link3
I have the following problem and I want to know if my thought is correct: In one $LC$ circuit, on which $C=4,0\mu F$, the maximum potential difference across the capacitor during the oscilations is $V_m=1,25V$ and the maxium current across the inductor is $I_m=50mA$.
$(a)$ Find the inductance of the inductor. My solution was: first we note that the charge on the capacitor satisfies the relation $q(t) = Q \cos (\omega_0 t + \phi)$ where $Q$ is the maximum charge. In that case, the current across the capacitor must be $q'(t)=-\omega_0Q \sin (\omega_0 t + \phi)$. The negative sign evidences that the charge is leaving the capacitor and flowing in the direction of the inductor. So this must be the same rate at which the charge flows through the inductor, so the current through the inductor must be $i(t) = \omega_0 Q \sin (\omega_0 t + \phi)$. In that case the maximum current must be $\omega_0 Q$. Since $Q = CV$, the maximum charge is obtained with the maximum potential, so $Q = CV_m$, in that case the maximum current is $I_m = \omega_0 CV_m$. Now I've used $\omega_0 = 1/\sqrt
$$I_m = \frac
$(b)$ Find the frequency of oscilations: My solution was to use $\omega_0 = 2\pi f$, so that we have $f = \omega_0 / 2\pi$, in that case we have:And using $C=4,0\mu F$ and $L=2500 \mu H$ I've got $f = 10^4/(2\pi) \operatorname
$(c)$ Find the time on which the charge on the capacitor goes from zero to the maximum. I've analyzed graphically, the time it takes for the charge to go from the maximum to the maximum again is the period $T$. The time it takes to reach $0$ is one fourth of the period. So, since the time for the carge to get from maximum to zero must be the same as getting from zero to maximum, the desired time is:
And for this problem I've found $ t = (\pi \cdot 10^<-4>/2 )\operatorname
Now, is my thought correct in all three items? I'm preocupated because I didn't even thought about what happened to the phase. My thought was: "well, it's arbitrary, it will just have to do with where we start measuring $t$", but I'm not sure. Also, the manipulations in general, are they all correct?
Thanks very much in advance!
Let's distill your question down to its conceptual essence:
Given an LC circuit, the capacitance $C$, the maximum voltage $V_m$ and the maximum current $I_m$, can you find the inductance $L$.
That's really all there is to it since, once you find $L$, you know the frequency and the period.
(By the way, in an LC circuit there is only one independent voltage and one independent current).
The answer is yes, you can find $L$.
Since you know the maximum voltage, you know the maximum energy stored by the capacitor and thus, you know the maximum energy stored by the inductor (there is no energy lost in an LC circuit). Thus, you have the relation:
You can solve for L with this since you're given the other values and the rest follows.
Cramster is an a website delivering free online homework help to students. If you are a student and looking for free tutoring online then Cramster is one of the first places that you must refer.
Actually the whole setup is joint collaboration between Cramster and Chegg online communities. Chegg is the place student can ask/post questions online, on the other hand Cramster experts (users ) login at Cramster to view and answer questions asked over Chegg. At, Cramster experts earn Karma points for delivering correct answers which can be redeemed online for various products.
Below, we have placed a short review on features of Cramster free online homework help. Have a look …
Getting Started Over Cramster Free Online Homework Help :
You can begin with a simple online registration. After login. you will be taken to user page from where you will be able to answer questions asked over Chegg (subscription costs $14.95).
The user with free membership can view textbook solutions for free (few books with limited preview). On the other hand users with paid account are given complete access to all resources.Asking For Help?
The free online homework help at Cramster is somewhat limited and you won’t be able to ask some specific question. Users of Cramster can only view questions of users with paid membership over Chegg. Anyhow, there exits a lot of free educational stuff over Cramster.
The users with paid membership are provided with:
From the point of view of a tutor/expert you offer service in return of virtual karma points that can only be redeemed after attaining the threshold value. If you have some inclination for performing free online tutoring, then use Cramster to deliver free online homework help as an act of welfare. I have suspicion regarding some very high earning potential at Cramster.
You can also refer our post on LearnBoost free online grade-book or Faculty Project virtual classes.The Final Verdict:
I can say that Cramster definitely provides free homework help. No matter, it’s not 100% free; then-too a decent attempt to demonize education. A lot of information’s and solutions can be accessed freely over Cramster.
* None can answer an irrelevant questions. No expert can; the members must consider this issue while asking questions.Share this:
A short distraction from the Signal Generator project to make an LC Meter Shield!
It has been a considerable time since I posted. Blogging does not come naturally for me and I often prefer to just do things rather than write about them. I still haven't finished the Signal Generator although to be honest it is close. I am lacking motivation. I have pushed that project down a route which is no longer palatable.
Instead I have decided I will write about a small project that I made recently which works well and was great fun (for me) to make and build. I always need test equipment. it's a strange thing with Engineers. they need toys to make bigger toys!
In order to measure Capacitance and Inductance a piece of test equipment is often used called an LC Meter. This is a device which measures the amount of Henries an inductor has (Henries is the unit of inductance) or the amount of Farads in a capacitor (Farads is the unit of capacitance).
Inductor - an electronic component that stores energy for a short period of time by generating a magnetic field - normally made by making a coil of wire around a former. Sometimes special cores are used to improve the inductor's frequency response. Inductors are sometimes called chokes!
Capacitor - an electronic component that stores energy for a short period of time by producing an electrostatic field on two metal plates. The size of the plates and the distance between the plates changes the amount the of capacitance the component will have. The dielectric material between the plates also has an effect of the amount of capacitance.
I needed a way of verifying that the electronic components I bought or made are within the specifications I require! Component manufacturers print the nominal level of what the inductor or capacitor is but this varies considerably between batches and is often considerably off. Every good engineer needs a way of checking that parts are what they say they are.
There are plenty of hobbyist projects available on making an LC meter. This is my interpretation. If you do a search in google for 'LC meter circuit' several pages will be sourced immediatly.
I was directly inspired by Kerry Wong's blog post -
There was also an article in Everyday Practical Electronics issue in March 2010 using a PIC Microcontroller.
I decided to make an LC Meter which uses the arduino shield form factor and is easy to make and use. I'm hoping people will like it and use it. although most electronics hobbyists I know nowadays are all digital and no analogue - ho hum!
Most LC meter instruments use a free running oscillator at a known frequency. When the user inserts the component in question in parallel with the oscilllator the frequency changes. By comparing the new frequency with the old frequency and using some mathematics the value for the component can be obtained.
So. how do we make an oscillator? There are several methods and I have discussed this in previous blog posts. This project uses a comparator to make a square wave oscillator. The circuit is below:
The oscillator section is made up of the 100uH inductor and the 4.7nF Capacitor. These two components decide the frequency of oscillation. All the other components are to make the oscillator work and to provide a method of making measurements.
The formula for calculating the frequency of oscillation and the other formulae used in the project are below:
lets calculate the frequency of our oscillator:
L = 100 uH or 100 * 10^-6 H
C = 4.7 nF or 4.7 * 10^-9 F
PI = 3.142..
Therefore F = 1 / 6.284 * SQRT (100*10^-6 * 4.7*10^-9)
lets say 232 kHz.
So our oscillator will free run at 232 kHz using the above inductor and capacitor. If we then introduce another component into the oscillation this frequency will change and we can use the original frequency and information about the oscillator components to calculate what value the new component has.
Here is a short simulation video showing how the measurement stage works:
Now that we have a method of measuring the components we need a way of controlling the circuit and displaying the information.
To this end I am going to use the popular arduino platform because its a great piece of hardware for rapid prototyping! Here is the rest of the circuit:
The circuit is fairly boiler plate electronics. The frequency of the oscillator is measured by the arduino on pin 5. The firmware uses a special arduino frequency counter library - more on this later. The type of measurement is controlled by a switch selecting which type of component is being measured and then we also have two buttons for displaying the current frequency of oscillation or measurement function (which controls a relay) and a calibration / zero button. We finally have an 16x2 LCD display being controlled by the arduino to display the information.
Once I had prototyped the circuit and checked it worked - briefly I laid out a PCB and etched a circuit board. Here is the layout:
PCB Bottom Layer
I then etched and drilled the PCB and populated it with components. I was so excited I plugged it onto my arduino and tried to get it working straight away. It didn't but that's not surprising. If a project works first time nobody learns anything! Sometimes though I do wish projects would work first time - particularly at work!
The problems were minor and have been fixed in the layout so if I decide to make another version it will work first time - Here is a link to the Eagle files and other associated information:
Once I had checked that the oscillator was working with an oscilloscope I got on with writing the source code. I'm not the best programmer in the world so I used a lot of other people's work to get this circuit to work as intended. Kudos to Kerry Wong and his version of this project!
The reason this project is viable is because of the frequency counter library made and maintained by Peter Welter-Platz
Its a great library and it makes it very easy for people to measure frequency of signals with their arduino. Basically I believe the library works by comparing the frequency to be measured with one of the internal microcontroller timers. The result is then stored and available for interrogation.
Here is the code. it's not perfect but it does work:
It's long and it isn't pretty but it should be fairly simple to understand. The program sets up the libraries, variables and the buttons and LCD display. It then looks at which position the user component select switch is in and then performs the required measurement. If the user presses the frequency button the current frequency of the oscillator is displayed. If the user presses and holds both buttons and then follows the on screen instructions the unit calibrates. In order to calibrate the L mode the input terminals have to be shorted together. For capacitance mode the terminals must be open and not connected to anything.
Here is a video of the completed unit running on my arduino Uno in use.
There are things about the LC meter that I would do differently - there always are! I would prefer the device to have a larger measurement range - Inductors are ok but the capacitance range of up to 1 µF is not helpful. I often like to measure electrolytic capacitors and this unit can't do that. In order to achieve that I need to implement a frequency divider circuit on the measurement frequency pin so that I can then use a smaller measurement capacitor which increases the range. I would also like to add another relay which automatically shorts the measurement terminals so that when calibrating the inductor range the user doesn't have to short the terminals. All told though this came out very well!
Update: I got some valuable feedback from a reader who asked if it would be possible to implement the analogue section using a dual comparator. It is possible and I have selected the LM393 dual comparator to do this. Here is the full schematic:
Abstract: Linear Class A Preamplifiers LC506 /LV506 DATA SHEET DESCRIPTION FEATURES The LC506 and. 38 dB gain trim · 0.95 regulated voltage LC506 A voltage regulator is built on-chip to supply the. LC506 is 0.95V, while it is 0.90V for the LV506 LV506. This regulator feature of the LC506 allows it to be. PACKAGING · 8 pin MICROpac ( LC506 ) Both LC506 and LV 506 devices are capable of operating from a supply. ( LC506 ) · 8 pin PLID® ( LC506 ) · 6 pin MINIpac (LV506 LV506) BLOCK DIAGRAM VB VREG 4(6) 3(3.
Abstract: of the GS551 GS551 and LD549 LD549 were performed using the LC506 as a preamplifier. Figures 1 and 2 depict the. LC506 0.047 6 10K 5 6 4 1 5 10 GS551 GS551 1.0 7 3 2 8 R TRIM RVC 100K. in uF unless otherwise stated Fig. 1 LC506 and GS551 GS551 Hearing Aid Circuit GENNUM CORPORATION P.O. 0.1 RMIC 3.9K 2 6 LC506 4 RVC 10K 3 1 0.047 1 5 LD549 LD549 2 1.0. in ohms, all capacitors in uF unless otherwise stated Fig. 2 LC506 and LD549 LD549 Hearing Aid Circuit.
Abstract: LC506 and LC/LD549 LC/LD549 HEARING AID P ERFORMANCE 1. VB = 1.35 VDC To compare the performance of the LC/LD549 LC/LD549 in a system, the 549 was combined with the LC506 and a Knowles CI 1970 (112) receiver to produce. compared to the standard LC506 /549 circuit diagram. First, the 549 has 2 capacitors decoupled to the. ) Fig. 6 LC506 and LC/LD549 LC/LD549 Maximum Acoustic Output SSPL90 SSPL90 For more detailed information please.