Learning basic electronics for beginners is the primary goal of this site.
I still have a lot of updating to do on this and my other pages. Please check back soon and forgive any mistake and sloppiness as I shuffle things around!
Power supply used in my videos. There are larger ones that are cheaper if portability isn’t important. I primarily got this one because I can easily film it next to my circuits. Affiliate link ad.
Bench power supplies plug into the wall’s higher voltage alternating current (AC), and output a lower direct current (DC) voltage and maximum current limit that you set it to. They aren’t as cheap short term, or as portable as a 9V battery (and battery snap) or breadboard power supply (which also needs 9V wall adapter with 5.5 x 2.1mm barrel plug) that I use in many of my drawings. So I assume many people won’t buy one for a while.
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Basic electronics introduction:
You need to be familiar with basic circuits before you will be able to understand more complex circuits.
What follows is a drawing of an LED (Light Emitting Diode) with a 470 ohm current limiting resistor (To protect all components of the circuit from overheating). They are powered by a 9V battery, all connected together on a prototype breadboard.
The drawing above is of what is called an electronics prototype breadboard. Used to build test circuits. Breadboards have slots to insert wires into. Each row of slots is connected together electrically within the board. 5 connected slots across each of the two middle rows, and 2 rows of slots connected from top to bottom on both sides. Some boards don’t connect all the way from top to bottom along the sides, but I have never come across one like that.
Primary goals when building/designing a circuit:
Keep these topics in mind while you study electronics. You get better at them the more you practice and study. Most learning electronics material will explain simple circuits in great detail, and then expect that you already understand the basics while covering more complex circuits.
- Don’t let any part of the circuit overheat. Use components recommended by a competent builder. Usually by trusting their schematic diagrams until you get good enough at calculating wattage to select components yourself.
- Use components that provide the desired outcome. Typically Involves a bit of research unless you stick with exactly what a detailed schematic suggest. Start simple and progress from there as you learn more.
Visualizing electric current:
Current/electrons runs through all series (connected end to end) components and power supply equally. It is pushed by the power supply voltage and it’s rate of flow is limited by the components. It has enough similarities to water flowing through pipes being pushed by a pump, that it helps to visualize current in that way.
Breadboard power supply basics:
Breadboard power supplies can be damaged relatively easily. I suggest getting a number of them if you want to use them. 5 should be good to start off with. There’s a link to an AC to DC adapter a little bit further down the page. The breadboard power supply doesn’t usually come with an AC to DV adapter, even when it is part of a larger kit. Affiliate link ad.
There are breadboard power supplies that have pins that plug into the breadboard. They have to be powered at the barrel jack, typically with a AC to DC wall adapter.
Adjustable AC to DC adapter I really like. An affiliate link ad.
I really like the kit above for a single purchase to learn basic electronics and Arduino. This is an affiliate link ad, so I earn from qualifying purchases, which helps me devote time to improving this site.
Electronics involves the study of electric circuits.
A simple circuit needs at least a power supply and a load (one or more components that can safely handle the voltage of the power supply).
A power supply provides voltage and current. A load does something with that voltage and current. The load always creates heat and possibly light, sound, motion, etc. from the power provided to it by the power supply.
Physical appearance of commonly used through hole (wires sticking out) components:
Common Schematic symbols for components:
Low voltage incandescent light bulb circuit:
An incandescent light bulb can be connected directly to a power source as long as it is rated to handle that much voltage. They have a resistive filament that gets hot enough to emit light when a voltage forces enough current through it. They dim as the amount of current goes down (due to less voltage).
Schematic symbols are almost always used to represent actual components in electrical circuit drawings called schematic diagrams.
LED with protective resistor circuit:
LEDs (light emitting diodes) have almost completely replaced light bulbs these days. They must be inserted in the proper direction in order to light up. They also must be protected from too much current. Usually a series resistor is used to protect the LED.
Most LEDs need current limited below 20mA (20 milliamps). That is the same as 0.02A. Most resistors are rated for 0.25W, but should be kept below 0.125W.
Those topics are covered in more detail below.
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- LED must be inserted in the right direction to light up (forward biased). That is when the Anode (longer lead) is more positive, and the Cathode (shorter lead) is more negative. That assumes that the Anode lead has not been trimmed. Leads (pronounced as “leeds”) are the metal wires coming out of through hole components. Many LEDs also have a flat edge on the cathode side.
Other types of diodes have a band painted on the cathode side of the component.
- Schematic diagrams are drawings of circuits where symbols are used to identify components and their connections, instead of using drawings or pictures of actual components.
Minimum resistance to protect an LED from common low voltages
Until you are comfortable with calculating resistor wattage, here are some good minimum value resistors to use to protect an LED from a given voltage. This assumes you are using 1/4W (quarter watt) resistors, which are by far the most common wattage value used.
- 5V – 220Ω (two hundred twenty ohms)
- 9V – 470Ω (four hundred seventy ohms)
- 12V – 1000Ω (1k) (one thousand ohms/one kilohms)
Notice how I put over 4 times the resistance to protect an LED from a little more than twice the voltage. Resistors get a lot hotter as voltage rises, and therefore current needs to be limited more to prevent the resistor from overheating.
A couple current through just a resistor calculations:
- 5V/220Ω = 0.022727…A (which is 23mA rounded off)
- 12V/1000Ω (same as 1k) = 0.012A (same as 12mA)
Current through a resistor and a series LED that drops 2V:
- 3V/220 = 0.013636… (14mA)
- 10V/1,000Ω = 0.01A (10mA)
Protective resistor must have high enough resistance to limit current below 20mA for most indicator LEDs. At higher voltages, current will need to stay well below 0.02A (20mA) to prevent the resistor from overheating.
Most resistors are rated to dissipate a maximum of 1/4W (0.25W) of power. It is still recommended to stay below 1/8W (0.125W). Other wattage resistors are fairly easy to find. They should also be kept below half of whatever their maximum wattage rating is.
To calculate wattage, take the voltage (in volts) across a components, and multiply it by the current through it (in amps). W = V x I
Batteries are a cheaper and more portable voltage source than a plug in power supply. However, they need to either be replaced often, or recharged if rechargeable.
A cell contains the chemistry needed to provide a voltage. The nominal voltage will depend on the chemistry involved.
Nominal voltage is close to the average voltage that you can expect when a cell goes from fully charged (highest voltage possible) to fully discharged (lowest practical voltage).
- Alkaline has a nominal cell voltage of 1.5V. The actual voltage ends up being 1.6V while brand new (they aren’t usually rechargeable), and somewhere close to 1V when fully discharged.
- Lithium ion (li ion) cells usually have a nominal voltage of 3.6V, which ends up being 4.2V when fully charged and 3V when fully discharged. Always stay within that voltage range and it’s maximum current to prevent dangerous damage.
- Series cells: Cells must be at the same voltage and capacity (mAh) Connecting cells end to end (positive of one cell to negative of another cell) adds up the voltage of each cell when measured from the 2 far ends.
- Parallel cells: Cells must be at the same voltage when connected. Connecting the positive end of each cell to the positive of the others, as well as connecting the negatives ends together, provides the same voltage as one cell, but adds up how much total current can be provided to a load. Make sure the batteries are at the same voltage (no more than about 0.1V difference) before connecting in parallel.
Battery holders that connect the cells in series or parallel for you when you insert them in the proper direction are common.
A 9V alkaline battery has the chemistry of six 1.5V cells contained in one package.
“9 volt” lithium ion rechargeable batteries can only be charged to 8.4V because they are made up of two 3.6V cells (4.2V cells when fully charged). I prefer to call them almost 9V batteries.
Always use a proper battery charger for the chemistry involved, unless you have learned how to charge that chemistry safely.
Really nice looking resistor kit for those beginning studying electronics. Affiliate link ad.
Nice assortments of semiconductors. Amazon affiliate link ad.
- Information on this site is not guaranteed to be accurate. Always consult the manufacturer info/datasheet of parts you use. Research the proper safety precautions for everything you do.
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