Resistor Measurement

How to measure Resistor in a circuit. Long time ago, while I'm study electronics, my teacher always teach me to measure Resistor out from the circuit. We must desolder it and check. Nowadays, electronics circuits become more complex and tiny. It is difficult for us to remove the Resistor inside it .How we want to measure the Resistor inside the circuit without desolder it. In this case we cannot use Ohmmeter to measure the value of the Resistor. By proper calculation, it is possible for us to measure the Resistor condition by using a Voltmeter.

Balance Amplifier Circuit and Chip

I found example of amplifier chip from Sanyo that have balance output. They call it BTL, something like bridge amplifier. First example is digital type. They call class D amplifier. IC part no is LV49152V.


Second example is analog type. Its class AB amplifier type. IC part no is LA4632.



Next we will design Balance to Unbalance Converter circuit in order to measure it output by our ACDC Converter and Window Comparator circuit.

Balance Amplifier Output

What is balance output amplifier? Simple, it is amplifier output that not have ground connection. Meaning output is + and - signal, no ground. So, don't try to connect ground loop to - output terminal. It will make your amplifier spoil. Some people call it bi-amp or bridge amplifier but actually this name cannot simply apply because it is different of the circuit. You can find many balance output amplifier at digital amplifier circuit. We need filter circuit to measure the output. Analog amplifier also have balance type and no need filter circuit to measure it. Next I'll will show example of balance output amplifier circuit.

Simulation Software

So, what is simulation software you use? I had try CircuitViewer and I think it very nice simulation software. Friendly user and suitable for student. You can download it demo version here. It is from Japanese company but they have English version.

Electronics Symbol in Office Excel

Do we need to buy AutoCAD software to make some schematic drawing for our electronics project? If we have high budget and big business, maybe we need to buy it. But for me, to draw only a little component in a schematic, just using Microsoft Office Excel is enough. Sometimes big schematic also I'm using Excel. This can save my budget. Maybe you can try also using Excel to draw small schematic diagram. Except for simulation, we need to have AutoCAD with simulation software. But, how many times we use simulation for our circuit? For small count of component, we can download trial version of simulation software and simulate our circuit. You can download my electronics component symbol in Excel file at 4shared.com . Enjoy drawing..

Power Amplifier Ouput Measurement

How to measure output power of your Power Amplifier by using our ACDC Converter and Window Comparator project? Very simple, we need to apply our basic ohm's law experience only. Make voltage divider, then measure it output power by voltage measurement only. Means using Window Comparator measurement and monitor by LED.
What about Bi-Amplifier or Balance Output Amplifier? So, we need Balance To Unbalance circuit now. What is Balance Amplifier and what is Unbalance Amplifier actually? Next post I'll explain to you.

Measure Your Designed Circuit

Had you design any electronics circuit, but don't have any equipment to measure it performance? Share it with me and we can design it measurement circuit together.

Squarewave Oscillator

Here is example of Square wave Generator schematic. It can be use to measure optical or coaxial receiver circuit before input to I2S converter. Also can use as a checker for optical or coaxial cable and component either functioning normally or defect. So, no need to use expensive equipment such as digital player or digital signal generator. So, how to calculate it oscillation frequency? Simple, frequency equal to 1/R1C1 = 10 kHz for this circuit.

Share Your Circuit Idea

Hi, there. Do you have any circuit to share with me? Simple circuit only that we can talk about it. How to measure it or how functioning is it.

Optical Receiver Measurement

For optical signal input measurement, there are many style of measurement that we can do. It depend of the circuit. First I want to show only optical input line measurement, meaning not include SPDIF converter circuit. My method is we only make squarewave signal circuit plus optical transmitter then output it to our receiver circuit, convert to DC and measure it by our Window Comparator circuit and monitor by LED. Squarewave is about 1kHz by using logic IC. I'll show the circuit next. Do you have any idea to measure it without digital signal equipment or digital audio player source?

Digital Audio Circuit Measurement

How to measure digital audio circuit? What is a suitable circuit to use for us without an exspensive equipment? For me, if we don't have digital input source, we have to make analog to digital converter circuit, then connect it I2S signal out to analog circuit, then analog output connect to ACDC converter, then connect to Window Comparator and monitor by LED. I'll show the block diagram and circuit later. Then we can make digital audio measurement jig.

Using LED To Monitor Power Supply

Before, +/-15 volts power supply I design cannot monitor its output immediately after power on. So I modified the circuit by added a little monitoring circuit using resistor and LED (Light Emitting Diode). By adding it, we can immediately monitor the output after power on or AC on. How we make the monitoring circuit? First, we already know LED current need 10mA, and for my case I'm using 2 volt LED. So, 15 volts minus 2 volts equal 13 volts. Then 13 volts divide by 10mA equal 1.3 k. So we need to use 1.3k ohm resistor series with the LED to monitor the +/-15 volts power supply. By this circuit also we can monitor +/-15 volts supply at the power off state. We can see the LED light slightly dark after power off where meaning that +/-15 volts supply slowly discharge.

+/- 15 Volts Power Supply Circuit

I upload power supply circuit for our Window Comparator and ACDC Converter. It version is for 240 Volts AC input. For 100 Volts AC supply region, can change the transformer to 100 Volts specification. The regulator using IC 7815 and 7915 for 1 Ampere output. Be careful not to use 78M15 or 79M15 because its only can output 0.5 Ampere. Other components I think is common to any regulator circuits. Anyway if visitor had question, can discuss by sent comment.

Window Comparator and ACDC on action

I upload picture of pcb board Window Comparator and ACDC Converter on action. For interested visitor maybe can order by comment.

Power Supply

So what kind of power supply we need to power up our Window Comparator and ACDC Converter? In the last project for Window Comparator and ACDC Converter we need a power supply +/- 15 volts at 1.5 Ampere. How to calculate it? Later i'll show it.

Circuit to Request

Do you have any circuit or component to measure but don't have measurement equipment? Request it here and we can discuss and design together a suitable DIY circuit to work as a measurement jig.

Audio Output Measurement

I upload block diagram how we want to test an Audio of our Headphone, Pre Amp or Power Amplifier project. First we need Sinewave Oscillator source to input to our project board then output connect to ACDC converter then measure by our Window Comparator and monitor by an LED.

For example our project board output is 5 volts. Output of an ACDC should calculate (5 volts x 2 x 1.414) / 3.14 so we get 4.50 volts output from ACDC. By this value we adjust our High Limit and Low Limit at Window Comparator.

ACDC Converter Circuit

I upload sample of AC to DC converter circuit. Full circuit can download here. We will dicuss about it later.

Audio Output Measurement

So how we want to test our audio ouput circuit by using window comparator? Audio output is AC signal but window comparator only accept DC measurement. In this case we need to use AC to DC converter circuit to convert audio AC signal to DC signal then can be measure by our window comparator project. We also need Sinewave Oscillator circuit to input to our audio project circuit. Another way if we don't want to make Sinewave Oscillator, we can use computer software which I recommended is SigJenny from Natch Engineering. But in this blog we will discuss also about Sinewave Oscillator circuit later.

LED Limiter Resistor Value

So how to calculate limiting resistor(R8) to LED1?
As we know LED current is 10mA and LED voltage is for example 1.8 volt.
So R8 is power supply +15 volt to -15 volt equal 30 volt, then minus 1.8 volt equal 28.2 volt.
So R8 is 28.2 volt divided by 10mA equal 2.820k.
So R8 we put 2.7k (nearest value available).

Limiting Power Supply Measurement Spec

Look back at the Window Comparator schematic, there is R4, R5, R6 and R7 which is fixed by Jumper wire. By only using VR1 and VR2 we can adjust trigger voltage at pin 3 and 5 from -12V to +12V. Actually I using R4 and R5 is to limit the maximum trigger voltage what is call High Limit and use R6 and R7 to limit the minimum trigger voltage what is call Low Limit. For example our voltage input to measure is 5 volt within spec +/-0.5 volt, at High Limit, using R4, R5 and VR1, we can limit it minimum adjustment to accurately +5 volt and at Low Limit, using R6, R7 and VR2, we can limit it maximum adjustment to accurately +5 volt also. By doing this we are smartly confident at our measurement will not accidently going out of specification. So how we want to calculate the range of voltage that we can adjust at High Limit and Low Limit? In the shematic today I included it formula.

Window Comparator Voltage Adjustment

So, lets talk about my window comparator circuit. As you see in the diagram, this window comparator can measure voltage between +12V and -12V. By using VR1 and VR2, we can adjust the limit suit our specification. For example, we want to measure +5V voltage, and it have +/- 0.5V tolerance, we need to adjust VR1 output to pin 3 at +5.5 volt, and adjust VR2 output to pin 5 at +4.5 volt. So, if input voltage is more than +5.5 volt or less than +4.5 volt, the LED is dark. It will light when VIN is between +4.5 volt to +5.5 volt. By monitoring the LED we can know the spec of the VIN is in the range or not. In my case, I'm choosing an instrument spec of Op-Amp NJM2119.

Next we will talk about other component around the schematic.

Window Comparator

So we discuss back about window comparator which will measure power supply for us automatically by LED monitoring. I upload example of window comparator circuit that I design here. Please download and discuss about it together. It have four channel input maybe for measurement + and - voltage or Left and Right stereo audio output ( will discuss later, for now only power supply ). Full schematic diagram can download here.

Power Supply Measurement

So, how we want to measure our power supply had accurate level that we need after we make some power supply project?
Actually we will use window comparator circuit to measure it. Window comparator had many type and style of design. So, lets looks at each type of window comparator that we can make and use.

1. High limit measurement.
For high limit measurement, we will make measurement line at high limit and ignore it low limit.
2. Low limit measurement.
For low limit measurement, we will make measurement line at low limit and ignore it high limit.
3. High and low limit measurement.
For high and low limit measurement we will fix it high and low level limit.