Category Archives: Electronics Learning

Buying resistors

If you’re going to purchase resistors, don’t get these blue ones. The color bands that show the values don’t show up well enough against the blue background. They’re fine if you only use one value for instance, but if you regularly need to read different values, at least for me, I got a refund because they were so hard to read.

Get the ‘normal’ ones (used to be standard until, like too many things, manufacturers got cheap and started to use lesser quality) with a brown background

And watch out for the ones that have extremely thin leads. All of them that I’ve purchased from China have had very thin leads that are difficult to handle and bend way too easily.

I found resistors from a US supplier that have the brown background and the ‘normal’ fatter leads at a very good price. Here is their ebay  store:

Off course you can get them from other sources, too. I found them for sure at and

All about the L298N H-bridge motor controller module

Oh boy, was I confused about this module at first! I found a fair amount of bits and pieces about it, but could not find the complete info that I was looking for. So I decided to create this tutorial for others who want to understand it better. I’m not an expert, but I have figured it out well enough to make what I think is a very clear and complete basic ‘primer’ on this device. Whether it’s right for your project is up to you to determine, but here’s info about the module itself, and especially about the mysterious jumpers (at least they were the biggest mystery to me).

What is it?

This module is a very inexpensive and convenient package based on the L298 dual full-bridge rectifier chip made by ST Microelectronics. It can be used to drive speed and direction for one servo or two standard DC motors, and drive other inductive loads like relays and solenoids. It can be controlled by microcontrollers like the Arduino.

Here is the description of the chip (not the module) from ST: The L298 is an integrated monolithic circuit in a 15-lead Multiwatt and PowerSO20 packages. It is a high voltage, high current dual full-bridge driver designed to accept standard TTL logic levels and drive inductive loads such as relays, solenoids, DC and stepping motors.

You can see the data sheet on their website here: .

You could just purchase the chip and component parts and wire up your own parts, but this complete module is probably cheaper than the combined parts, and it’s certainly more convenient. As of January, 2017, the modules are selling on ebay for under $2.00! At this price they’re from China of course, but you can purchase them at higher prices in the United States if you can’t wait for the long shipping times from China.

I’ve read in forums that the L298 chip is about 15 or 20 years old, so there are better(?) chips available now. People seem to like the Pololu A4988 .  Stepper motor current limiting is apparently one of the big improvements, but none of the current-limiting chips come in this neat module format that I’m aware of. So this L298N module is fun and handy, certainly great for testing and little projects, but be careful if you need current-limiting features when driving stepper motors.

The module components

Here’s where I was the most confused. If you look at the auctions on Ebay you get the typical Chinese-translated-to-English descriptions that are neither complete nor understandable. And searching for other resources on the internet or YouTube results in some great information, I was not able to find any one source that was all-inclusive like I’m hoping this one is (for a basic primer anyway).

…More coming soon…

Using Arduino Nano and a relay to fire a solenoid

In my previous post I talked about using a motor, a cam, and a switch to fire a solenoid. That just wasn’t going to work because it was too hard to get the right pace of the solenoid firing. The motor voltage changed its speed, and the cam idea was too difficult to adjust the cam shape and location.

In this post I’m showing how I switched to the Arduino Nano to control the firing rate of the solenoid. With the Arduino, it’s a 30-second program change to change the rate of the solenoid firing as opposed to the ridiculously difficult process with motor and cams.

The first video below shows the solenoid firing using the default settings in the sample ‘Blink’ program in the Arduino IDE.


The video below shows the solenoid firing after I modified the delay settings in the ‘Blink’ program.

Series Circuit Defined

A series circuit is one in which items are arranged in a chain, one following the other, so the current has only one path to take. The current is the same through each item.

Series circuits are used for several reasons:

1. To increase a voltage source.

The following is true of any standard battery, but let’s use the AA battery as an example. If you put one AA battery in a circuit, you will have a power source of 1.5 volts because that’s the voltage of a standard AA battery.



If you want 3 volts, you can place two AA batteries in series which gives you 1.5 V + 1.5V, which equals 3V.

AA double batteries and lamp





Put three AA batteries in series and you will get 4.5 volts, etc.

More coming soon.


Also see:

Your First Electronic Circuit!

So you want to learn about electronics! Good for you! The sky is the limit when it comes to this field, but let’s start with a very simple circuit.

Lighting up a light emitting diode (LED).

The entire circuit is very simple — it consists of an LED, a power source (batteries), and a resistor to limit the current through the LED.

Light emitting diodes will emit light when a voltage is applied to them and current flows through them. Different colors and types of LEDs may require different voltages and currents, but a standard red LED requires 1.7 volts and .02 amps (20 milliamps, or 20 mA).

Here is a how to build your circuit if you’re a very beginner without many tools yet.

basic LED circuit

I have two AA batteries (1.5 volts each) that are connected in series to make about 3 volts. (Click here to learn about series connections.)

They are in a little battery holder with alligator clips that I soldered on to make the connections easier.connected to the LED and a current-limiting resistor.

I used an extra alligator clip to connect the resistor to the LED. You could use a paper clip, or just wind them together.

Here is what the circuit looks like in a schematic diagram:


Even this simple circuit needs a little forethought.