How to Use a Multimeter to Check Voltage.

Voltmeter is an instrument in use to test voltage from voltage source and or potential difference within a circuit. Different voltage source include battery, alternator, solar cells and various transducers. And the transducer may be at the input or at the output of a device or circuit.

The voltmeter could stand alone or as part of a Multimeter. In a Multimeter, we have ohm meter, voltmeter and ammeter together in one test instrument. However, to check a voltage from a voltage source you need to follow this instructions:

How To Use a Voltmeter In Multimeter

  1. Switch the knob or button of the Multimeter to Voltage
  2. Connect to DC voltage range, or AC voltage range. However, this depends on the voltage source
  3. However, consider how much voltage you expect from the source
  4. But, choose the higher range of the voltmeter compare to what you expect
  5. For DC Voltage, locate the positive and negative connection of the source
  6. In fact, positive of the meter is usually red, while negative is usually black.
  7. Or, positive has +VE sign and negative has – VE sign respectively
  8. Then, find the negative and positive probes of the meter
  9. Connect positive probe to positive of the source, and negative probes to negative of the source
  10. But for ac voltage source, there is no permanent positive or permanent negative. Therefore, you can connect the positive or negative to any point of the source

A Multimeter, could be digital or analog. Digital Multimeter is easy to use than analog Multimeter, but analog has its on advantage, Obviously, with the digital meter, you can read the value of measure voltage as figure on the display. But analog meter does not display its value as figure, which you have to read the figure the pointer display to.

In order to use voltmeter to measure potential difference within a circuit, locate the two points of interests. Then follow the list 1 to 8 above for DC volt. But for AC volt, follow the how’s 1 to 7 and 9.

How to Test for Continuity | Hunker

How to Test for Continuity | Hunker

A continuity test is a simple way of checking whether a circuit is open or closed, and it can help you identify a bad switch or outlet, as well as assist you in identifying wires in electrical boxes.

Continuity Testing

What is continuity testing and why carry out this test?

1. Voltage not getting to where expected

2. High value resistance measurement in a circuit

3. Low output or no output experiences

4. incorrect or improper system functions

5. Lost signal at an input or output.


Electrophoresis Power Supply Unit

Electrophoresis technique is a method of separation in clinical laboratories to separate charged molecules from each other and into their constituents’ components. This happen in the presence of electric field. The electric field device is a typical ion exchanger, You can use it to separate many things such as proteins in body fluids for example urine, proteins in erythrocytes such as hemoglobin and Nucleic acids. Typically DNA and RNA just to mention a few.

In fact, many factors are responsible for the output of this procedure and are inherent, external and environmental. Inherent factors include magnitude of charge, charge density, molecular weight, and shapes of the material under investigation. Likewise, external and environmental factors include pH, electric field, viscosity of the solution, and temperature.

However, this process employs the use of electricity to separate charges in the presence of electric fields. The main electrical parameters used in electrophoresis are Voltage and Current or Power. High voltage is responsible to provide the electric field. However, when current pass through a substance with resistance and in this case the buffer, it evolves heat. Therefore, it is important to choose carefully combination of parameters to use for a particular procedure.

Electrophoresis Instrument

A typical instrument comprises of an electrophoresis tank and an electrophoresis power supply. The power supply is usually high voltage source to create the presence of electric field within the solution. The tank is a plastic material with two electrodes of tungsten or constantan. One electrode connects to the negative terminal of the power supply. The other electrode connects to the positive terminal of the high tension power supply. Moreover, the tank serves as container for the buffer and gel.

In electrophoresis, you hold one electrical parameter, current, voltage or power constant, but ideally you keep voltage constant. That is, keeping the voltage steady. But why is this so?

  1. Under constant current conditions (velocity of moving charge is directly proportional to current). With constant current, the velocity of the molecules is maintained but generates heat.
  2. With constant voltage conditions, the velocity of moving ions slows, but it does not generate heat during the course of the run
  3. At constant power conditions, the velocity slows but heating is kept constant

Electric Circuits Basic Study

Electric circuits basic study include many topics which include  electric circuits component, electric circuit drawing and Kirchoff’s law, projects. Others are electric circuit simulation software, electric circuit series and parallel, and electric circuit test,

An electric circuit is a means to transport electric power from the source to the load. For electricity to do any useful work, current must flow. Electric current can flow only through conductors and to certain degree in semiconductors. However, insulators will not permit such flow.

An insulator is a material in which electron cannot move easily from one atom to another. Insulators protects against harmful effects of electricity. They have more than four electrons in the valence. Types of insulators include ceramic, glass, plastic, rubber, air, and wood etc.
Atomic structure of insulators:

Electrical conductor materials

A conductor is a material in which electron can move fairly well between atoms. Two metals of the same materials and thickness at different length have different resistance values. The two metals at same length but different thickness exhibits different resistance value. Long wire has more resistance compared to short wire. Thin wire has more resistance than thick wire. A semiconductor is a material such as silicon. Semiconductors are either conductor or insulator materials.

First, there must be a closed path or circuit for current to flow. The closed circuit contains a conductor covered with an insulator, a switch, a source of power (a battery for example) and a load. An example of a load is your appliances. Second, the circuit must have a continuous supply of electrical charges from an electric field such as a battery. Electron (electric current) flows from negative to positive, that is, electron flow.  However, in conventional current flow, electron (electric current) flows from positive to negative. Besides, in calculations, you arrived at the same answer, either you choose, electron flow or conventional current flow. But the best approach is that electron flows from negative to positive.

Electric Circuits Component

Flow of current is determined by applied voltage and resistance (or impedance) in the circuit. Keeping resistance constant, increased voltage produce more current flow; reduced voltage reduces current flow. Keeping voltage constant, increased resistance produce less current flow; reduced resistance increases current flow. You can measure current in a circuit with Ammeter and the unit of current is Ampere. A typical electric circuit controls the working of a hot air sterilizer.


Resistance is the property of a material to oppose the movement of electron (current). All electric circuits has inherent resistance. For example, internal resistance from source and resistance in the wire.
Resistor is the name given to a component with pre determined resistance value. Resistance is a characteristic of many electrical appliances called load. Every circuit has certain resistance value
The resistance value of circuit wiring should be minimal to reduce electrical power loss. Some Energy source such as battery has internal resistance and should minimize. You can measure resistance in a circuit with Ohm meter. Unit of resistance is Ohm.


In all electric circuits, electrical voltage is the pressure pushing current to flow in an electric circuit. Unit of electrical voltage is V. You can measure voltage in a circuit by voltmeter. A multimeter has different ranges to measure current, resistance and voltage. That is a multimeter, has Ammeter; Ohmmeter, and Voltmeter. Some versatile meter has more values to measure.

Electric Circuits Law

Ohm’s Law

The voltage across a conducting material is directly proportional to the  current through the material, that is, v = Ri, where R (resistance) is the proportionality constant. That is to say, voltage drop or potential difference along a conducting path is directly proportional to the current flowing in the material. Meanwhile, current flowing is a dependent on the resistance of the material.basic electric circuits slopeFrom the slope, you see that when current increase, voltage increases, and when current decreases, voltage also decreases.
With constant voltage, increase resistance, will reduce current. Reduce resistance will increase current. Current (I) = Voltage (V)/Resistance (R). Learn more as we move on to electrical calculations.

Hot Air Sterilizer Oven Principles

Hot air sterilizer Hot air or oven is a device in use to sterilizing items that moist should not penetrate. That is items that will damage by exposure to moist heat. Such items include powders, sharp instruments and petroleum products etc. In other words, we use dry heat sterilization for articles for which other methods such as using autoclave are not good. At the same time, hot air ovens are in use for articles that can withstand high temperature.

Hot Air Sterilizer Description
There are two types of hot air oven. One type is electrical home appliance for baking and the other is used in sterilization. In this text, we have more in hot air oven sterilizer. It finds uses in laboratory, pharmacy and in surgery. The oven uses dry heat to sterilize articles. Temperature range for this device is from 50 to 300 °C (122 to 572 °F). It has double wall insulation which keeps the heat in and conserves energy. However, the inner layer is a poor conductor and outer layer is metallic.
However, the internal wall is isolated from the external wall by insulating material which keeps internal high temperature conditions and delays the transfer of heat to the outside.
There is also an air filled space in between to aid insulation. An air circulating fan helps in uniform circulation of the heat. The inner space contains adjustable wire mesh plated trays or aluminium trays and may have an on/off rocker switch. The capacities of these ovens vary. Most hot air sterilizers receives power from electricity. This is either 220 v, 50 Hertz or 110 v, 50 Hertz  depending on the country
Hot Air Sterilizer Principles

The oven produces heat through sets of resistance heating elements, The heat  energy is being transferred to the chamber by natural means as well as by forced convection if there is a fan. The heating elements are located in the at the bottom of the oven

In order to use the sterilizer/oven, first activate the main switch, press the button or dial the knob to set the oven temperature and set the sterilizing timer. The inner chamber of the sterilizer will heat up till the oven reach the set temperature. When the sterilizer reached the set temperature, a thermostat activates the timer and the timer begins to countdown until it reach the set time. At this time, it switch off power to the heating elements. However, the elements continues to work via the thermostat control until the set time.

Hot Air Sterilizer Parts and Functions
Hot air oven controls make use of the following components

There is a thermostat controlling the temperature. The thermostat automatically regulates  and maintains already set temperature. It on or off a device such as an heating element when the temperature reaches a certain set point. Some types are of simple rod thermostat while some are electronic or digital. 

Glass thermometer is an instrument for measuring and indicating temperature. Typical one consist of a narrow, hermetically sealed glass tube marked with graduations and having at one end a bulb containing mercury or alcohol. The mercury or alcohol expands and contracts in the tube with heating and cooling. In our context, the thermometer visually indicate the working temperature of the sterilizer.

Basic Hot Air Sterilizer Circuits Diagram

Hot air sterilizer oven circuit diagram

Use of Hot Air Sterilizer

A complete cycle involves heating the oven to the required temperature.  Likewise, it maintains that temperature for the proper time interval for ‘that temperature’. Then turning the machine off and cooling the articles in the closed oven till they reach room temperature.

The standard settings for a hot air oven are:

  • 1.5 to 2 hours at 160 °C (320 °F)
  • 6 to 12 minutes at 190 °C (374 °F)
We use temperature sensitive tapes or other devices like those using bacterial spores to work as controls, to test for the efficiency of the device in every cycle.

The Concepts of Electricity and Magnetism

Electricity and Magnetism

There is close relationship between electricity and magnetism. You can cause electric current to flow in a coil of wire. This is when you cause a permanent magnet  to move around (or towards) the wire or coil of wire. The  energy of the magnet (magnetic energy) forces electrons in the wire to align in specific ways and produce electricity. The amount of electricity produced depends on the number of turns of wire, the strength of the magnet and how fast you moving the magnet or the coil. In fact, this is the basis of main electric power generators. The two ends of a magnet are North and South pole respectively.electricity and magnetismBasically, you can’t have so much electricity without magnetism. Electricity and magnetism are not exactly the same but there is a close relationship between them.

When you move a conductor in a magnetic field, you will produce electricity in that conductor. However, you need one of the two materials, (coil of wire or permanent magnet) to keep moving in order to produce the electricity. In fact, there must be a change in the magnetic field of force to produce electricity. Electricity produced depends on the number of turns of coil of wire and the rate of change of magnetic field.

Temporary magnet from electric field

You can make a temporary magnetic field (a temporary magnet) from electricity. When you pass a current through a piece of wire, you have a magnetic field around the conductor. The magnetic field is called ‘magnetic field of current’.  You can increase the strength of the magnet by making the wire into a coil. Likewise, increasing the number of turns of the coil. On the other hand, you can increase the flow of current. This is the basis of all electromagnetic devices such as electric motor, relay, transformer, induction furnaces and solenoid. Using Fleming left hand rule, you can determine the north and south pole of the temporary magnet. Meanwhile, you can make current to flow in a wire from permanent magnet.  

Induced Current from Magnetic Field

There is a direction to which induced current from magnetic field flows. The current will flow of in any of two ways clockwise or anticlockwise. The direction of flows depends on if the magnet move towards the coil of wire or moving away from it. If there is no movement relative to the magnet and coil of wire, there is no induced current.

Any change in the environment of a magnet and a coil of wire, will cause am EMF or voltage to be ‘induced’ in the coil. It does not matter how you produce the change.  You may move the magnet towards or away from the coil. Or you move the coil towards or away from the magnet. You might as well rotate the magnet or the coil. As long there is a movement you induce current.  You can confirm which direction current flows by using a galvanometer or an ammeter. Using Fleming right hand rule, you can determine the direction of flow of current.

Wind and Solar Power Systems

Solar and Wind Power System

Wind and solar power systems make use of the following components and materials to set it up. When size those components correctly will produce enough power for your use. You can equally sell excess power to the grid. Listed below are major components for your power project.

Many solar projects fail where they need it most. The reason is not far-fetched. Likewise, most failure arises from improper component sizing or missing parts, Again, some components are very small, yet are crucial to proper function of the system.

wind and solar power systems

Success Factors for wind and solar power systems
  1. Enough batteries to maintain the state of charge for a long time and a minimize state of discharge.
  2. Large enough solar panels to provide sufficient charging current even at an off-peak period.
  3. Correct size charge controller in the voltage and current
  4. Voltage controller in system when you don’t need battery
  5. Size of cable. Position the battery very close to the solar panels and charge controller as possible to minimize cost because you will need large conductor size for high power output.
  6. The secret of successful solar and wind installer is the low voltage battery disconnect they incorporate in the system.
  7. Inverter type and sizes. You would not install a square wave inverter where you need a pure sine wave. Otherwise the system would fail because it would not be able to power equipment for which it sufficiently.

In essence, some people think anyone could install solar without sufficient knowledge and skills. Yes! You can learn it and acquire the knowledge and meanwhile, seek support from experienced source when needed.

For some installation, you may include charging the battery by mains grid supplies. This is the case you use the system as a backup Uninterrupted Power  Supplies systems.

For your wind power system, you cannot feed the output of the alternator directly to the load. This is because current and voltage from this system is erratic. Therefore, you need battery to receive charging current from the dynamo, then the battery feeds the inverter which in turn feed the load. You may as well use the voltage from the directly to power low voltage direct current.


Electronics Board Assembly

Electronics Board Assembly is a special job for an electronic technician, most especially in prototyping, or research. Tasks involve in this job include cable assembly, electronic components mounting, and soldering etc. The technician should be able to read and explain electronics assembly drawing, read and take schematic and or circuit diagram. The whole idea is to put the components into the printed circuit board and working correctly. This position also consider knowledge of electrical safety and classes of equipment as important.

Use of printed circuit board make the job easier and for mass production. This is unlike the past where components are hard wired together. Knowledge of schematic drawing and pcb layout editor is an essential skill for this job. This may not be too much of a priority for contract staff hire for this task but for the technician this is part of personal development curriculum.

Component Electronics Board  Assembly

All electrical and electronic components has different symbol to know one from the other. We use this symbol to know each component in a circuit diagram. For example, transistor is different from a capacitor. Though, some component may look the same but their look in the diagram is not. A power bipolar transistor look like a fixed voltage regulator, a thyristor and a field effect transistors.

The only thing to tell apart by looking is their part number. Further to this, know the difference between passive and active components is important. This is because you take priority to assemble the passive before the active because active components have more threats to damage. The damages in danger of too much heat and electrostatic discharge.

Electronic components pinouts

Electronics components pin out for Electronics Board Assembly

Pinouts for a part number of a component may be different for the same component of different part number. Take care to insert the right legs in the PCB board before soldering.

The pinouts shown in the picture above display different shape for the same voltage regulator. The same is true for transistors, capacitor, transformer, and integrated circuits (IC). The same thing relates to triac, diodes, opto isolator or optocoupler, etc.


Electronic Projects DIY

Many times hobbyist, DIY enthusiasts and even experience technician need help at one time or the other in pursuit of a goal. For the student, hobbyist or DIY enthusiasts, you likely require more explanations and clarity at some points in your electronic projects DIY.electronic projects diy

For the experienced technicians, you are pursuing a goal which might be new or existing projects and need to outsource for early accomplishment. This is where we come in to assist.

Printed Circuit Board Projects

Contact Us for your electronic projects DIY schematic and printed circuit board projects. Send us your drafts or tell us more about your project ideas. Then we can discuss the plan together.

Training on PCB Designs

Do you want to use printed circuit boards for your projects and prototypes but you always hand wired your components? It is time to learn to using schematic and PCB editor. It makes your work easier and limits or totally eradicates error. However, error you might have is any committed in your design.

Components for your electronic projects DIY?

Save yourself the problems of wasting time brainstorming alternative methods or equivalent component to use when the actual is not available. Tell us your need and we will help you out. Besides, you might need specialized components which might not even be electronics. Or electronic projects kits, we will assist you to make your plan a success.

Need help in your prototype?

In the first place, you may consider buying pre assembled PCB module for certain work. And all the same need a replacement module for some assignments. We are ready to help you in whatever capacity.

Consequently, we want to assure you are not alone in your journey to success in your endeavor. Specifically for students, hobbyist, technicians and as many as are working on equipment or appliances.  Ask Us today and we are glad to help you.,


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