Make: Electronics Chp2 Experiment 10

Experiment 10 “Transistor Switching” involves one of the most important electronic component in all of electronics. The transistor. To truly appreciate how the transistor has impacted technology. I highly recommend Googling about the importance of the transistor. As this will hopefully foster a deep appreciation for this piece of technical genius. So many things that you and I own would not exist the way they do today if it weren’t for transistors.

The first circuit in this section that you’ll create is one by which you expose your finger to two jumper leads. The harder you press on the end of the leads the brighter the LED in the circuit becomes. The current flowing through your finger and the positive bus is being amplified by the transistor at its base. That said, this experiment is safe and there is no electrical sensation. Reason being is that a 9v DC power supply is negligible in this scenario.

However, never ever use two hands in a situation like this, or plainly put, don’t ever put yourself in series with a circuit by holding the leads in both hands. You definitely want to avoid current flowing through your body, even a small amount.

*In the video my wife has the two leads touching one finger and is holding the shielded unexposed wire in the other hand. 

Interestingly enough for the beginner, you’ll observe that the emitter of the transistor is connected to the LED on the board. This provides enough current to flow from the transistor and light the LED. Some of that electricity comes directly from your finger.

More importantly, the major player in this equation is the collector lead  on the transistor, it’s sourced to the positive bus terminal of the board. The base of the transistor is responsible for controlling the current that comes from your finger (in this particular setup). So in a nutshell, we have current flowing into the collector, that current flow is regulated by the base of transistor, and then resulting current from the emitter lights the LED.

During this section of the text, more information about various transistors and the differences between PNP and NPN transistors is reviewed.

Finally, you’ll augment the circuit and add a potentiometer. Under observation you should note that bipolar transistors won’t respond unless the amount of voltage present at the base of the transistor is higher that what’s at the emitter – at least 0.7v to be exact.

Personally, I believe that thus far, this section in addition to the text regarding capacitors is extremely important. Definitely take the time to get the circuits right but more importantly make sure you understand the material and how the components actually work.

Transistors play an extremely important role and it’s worth learning all you can.

Experiment 10 materials:
Bread board
2n2222 Transistor
9volt Battery
470 ohm, 1M resistor
500k Potentiometer

Make: Electronics Chp 2 Experiment 9

Experiment 9 “Time and Capacitors” is a soft introduction to the capacitor. The capacitor is a very interesting component and with it you can measure time. However, this is the first component that actually requires that you pay full attention to how it is placed on the bread board. Failure to check the polarity can result in the component exploding. As always eye protection should be worn, but especially when it comes to capacitors.

As far as measuring time. The circuit uses two tactile switches.  One switch will charge down the capacitor while the other will allow the capacitor to charge up. With a timer, i.e., smart phone or watch, you can observe how long it takes for the capacitor to charge. During my run at this experiment it took the capacitor about 1 to 1.5 seconds to charge.

The actual science behind the capacitor, or simply put,  the beauty of its function can be realized by the understanding of the RC network; of which Mr Platt provides a great over view. Most college text books get down in the weeds on this topic because it’s such a an important concept. However, what is given here is definitely sufficient for the beginner.

Moreover, this chapter continues to go deeper into the concept of the RC Network by teaching you how to graph the voltages during charging time. In addition to further tweaks to the circuit and experimental discovery.

Although it is not needed at this point, I would look into getting an oscilloscope. eBay has them for cheap if you’re on a budget. So definitely look into getting yourself one.

For what it’s worth. Electronics is basically all math. Hard math. Although, you probably won’t get any of that here (hard math). Don’t let this fact run you off if you’re math averse. Once you see how the math in electronics theory works hand in hand with the physical application – you’ll probably love math as much as I do….well maybe not that much.

Experiment 9 materials:

Bread board
9volt battery
2 Tactile switches
Generic LED
470 ohms, 1k, 10k Resistors
0.1 uf, 1 uf, 10 uf, 100 uf, 1000 uf Capacitors

Make: Electronics Chp 2 Exercises 6-8

Exercise 6 “Very Simple Switching” introduces manually operated switches. The circuit  you will construct can use either a SPDT or DPDT toggle switch. For what its worth, this circuit will require some patience if you have big hands and your toggle switch doesn’t have screw terminals. One of the things you have to get used to fairly quickly working in electronics is tight spaces, and very small components which can sometime find themselves on a crowded board. So bring lots of patience.

That said, one of the man take-aways is developing a cursory understanding of how switches work. The text provides a great overview in the section, “Fundamentals: All About Switches“.

Further along in the chapter the author presents schematics and a few symbols. Schematics in my limited opinion is the linqua franca of circuits – no different in importance as hieroglyphs are to Egyptian culture. Learning how to read schematics will definitely open the world of electronics to you in a much deeper and rewarding way. More importantly, the further you venture into this hobby, learning how to read schematics is not an option, its a requirement.

Exercise 7 “Investigating a Relay” introduces the reader to the function of a relay.  You’ll learn about it’s remote-controlled ability when it comes to receiving a signal sent by a circuit.

This however is another circuit that may present a few challenges for those with big hands. However, my hands are pretty big and it simply just requires focus and patience.

Once you connect power to this circuit you’ll notice the clicking of the relay right a away.  Using the SPST toggle switch will initiate the remote-controlled action. Holding your DMM probes to the leads of the relay while in continuity mode will produce a tone. The tone is an indication of a complete path that allows current to flow. The clicking of the SPST causes the tone to stop, thus the flow of the current is blocked.

In the spirit of full disclosure.  I sacrificed a relay to science when performing this exercise in the first edition. For some reason I kept that relay. So I didn’t perform that part of the exercise this time around. However, I would advise that anytime you get the opportunity to see how something works on the inside – go for it.

Exercise 8 “Relay Oscillator“. As a beginner you are probably smiling a little bit at this point because you finally get to used breadboards.

This circuit visually demonstrates oscillation via the use of two LEDS. From my experience, LEDS are kinda like break points when debugging  code depending on how they are used. Anyway. The schematics used in the book are super-user friendly. That said, this is probably something I would not get try and get used to. I actually applaud the author for making the schematics in this fashion as it definitely helps the beginner to focus on the task at hand without the complexities of a real schematic. Honestly, there isn’t that much difference but eventually you are going have to learn how read traditional schematics if you want to go further in electronics.

Note: Batteries are expensive. I’d highly recommend buying a power supply if you are serious about this hobby. It is definitely worth the money. I’m not advocating any particular brand but this what I use.

Exercise 6 materials:
Hook up wire
9volt battery
470 ohm
Alligator clip leads

Exercise 7 materials:
9volt battery
DPDT 9VDC relays(2)
Alligator clip leads

Exercise 8 materials:
9volt battery
batter connector
DPDT 9VDC relay
Tactile Switch
470 ohm resistor
1000 uf Capacitor
hook up wire

Make: Electronics Chap 1 Exercise 5

When life gives you lemons, make electricity. OK…that was kinda corny.

The last experiment in chapter one presents us with an old school kitchen table experiment; making a battery from lemons.

For the exercise I actually had to run out and grab some supplies, mainly the lemons, lemon juice, and some zinc coated brackets from Home Depot. The brackets set me back about $2.50 for a pack of 4.

Overall, this exercise is an attempt to mimic the function of a battery. For this to occur properly, you must have the correct chemicals working for you, i.e., copper, zinc, and lemon juice. In regards to copper, nowadays US pennies are copper plated only. So to get the most out of each penny in the circuit, look for the brightest (newer) pennies that you can find. As far as zinc is concerned. Using a galvanized metal part coated with zinc works fine as suggested in the text. If you venture out to the hardware store just look in the aisle where the door brackets are located. The packaging should say something like “Zinc Coated“.

Out of all the exercise thus far, this is probably the most difficult in terms of achieving success and a little messy. However, the key is to take your time, secure the correct parts, and follow the instructions exactly as given.

For what its worth I was able to light my LEDs on the first try. So I’ll try to provide you with a few tips to increase your level of success.

1. Put your lemon halves into a small glass jar; helps to keep them up right.
2. Saturate your lemon halves with lemon juice from the lemon juice bottle.
3. Make sure that you are alternating between bracket and penny throughout the circuit.
4. Make sure that the brackets and pennies are close but not touching; a half-inch apart worked for me.

All in all this was a pretty cool experiment  for those who have never done anything like this before.

Exercise 5 Materials:
Lemons or Lemon Juice
4 U.S. Pennies
1 inch or larger zinc plated steel brackets
Test leads with alligator clips
LED (Low Current)

Make: Electronics Chp 1 Exercises 3 – 4

Exercise 3, “Your First Circuit” provides the reader with the important skill of learning how to read resistor values; a good skill to have. Although one can use a DMM to determine the actual resistance value. Learning how to visually determine the the value of a resistor is sort of like a rite of passage for anyone serious about electronics as a hobby. Take that step, learn how to read the values, you’ll be better for it.

This particular circuit is also your first introduction to the LED.  Some areas of focus include visually determining the positive and negative side of the LED, and how to determine both forward voltage and forward current.  Note: always check electronic components to determine the manufacturers limit in respect to those forward voltages and currents. Or you’ll just waste money on parts.

The construction of this circuit is simple and should not present any difficulties. You’ll start with a 2.2k resistor, and continue to swap out different resistor values while observing the effects on the LED.

Exercise 4, “Variable Resistance“. Once again, we are tasked with sacrificing a component for the sake of science. However, as per Mr. Platt. Readers complained after the first edition of the book about not wanting to ruin a usable component. Honestly, if you take your time, you can carefully reassemble the potentiometer and it will work perfectly fine. The overall benefit of the disassembly is to get a peek inside it’s inner workings; this is one of the more interesting looking components you’ll probably come across early on. Plus, people like us, Makers, and natural born Engineers need to know how things work. Right?

The circuit in this exercise is the first time you’re in a position to actually manipulate the amount of resistance +/-  in real time. The take-away here is to realize how one might damage a component by varying the resistance in the circuit. To drive the point home, you can sacrifice the LED to science as well.

Additionally, the circuit is followed up by adding a 460 ohm resistor which is used to protect the circuit in the event the potentiometer goes to zero; a fail safe.

Lastly, the reader is treated to an excellent overview  of the fundamentals of Ohms law , Series and Parallel, and how to measure current in a circuit. All of which are important topics for the beginner as you take more steps toward learning electronics.

Exercise 3 Materials:
9volt battery
470 ohm, 1k, 2.2k resistors
Alligator Clip Test Leads

Exercise 4 Materials:
9volt battery
470 ohm, 1k
LED (2)
Potentiometer 1k linear

Make: Electronics Chp 1 Exercises 1 – 2

Exercise one, “Taste the Power” will probably have the electronic neophyte taken aback a bit. You’re literally preparing yourself for a taste of electronics. Don’t worry though, a 9-volt battery to your tongue is not as shocking as it may appear. Notably, the text regarding Ohm fundamentals and how a battery works is the emphasis of importance.

Exercise two “Let’s abuse a battery“. Here’s another project that may possibly cause concern to the uninitiated.  Questions may rise such as, “Will the battery explode?”. Most likely not, but you always have to be careful and adorn safety eyewear, especially when working with electronics.

The first part of exercise two demonstrates how heat is generated as a result of electricity flowing through the battery cable wires and the electrolyte inside the battery. NOTE: make sure you are using an alkaline battery and not a rechargeable one. 

The take away at least for me for this exercise is an attempt to answer the question, “How much current actually flowed through battery case wires before the battery shorted?” As per the material, attempting to measure the current with your DMM may blow its internal fuse. However, there are ways to properly measure current with your DMM, but it’s not covered here.

As an alternative to testing the amount of current with the DMM, we sacrifice a 3-amp fuse instead. Initially the 3-amp fuse I used was definitely much stronger than anticipated. I ended up connecting the battery wires directly to the fuse so it would blow. The take way here is to understand one of the roles of a fuse – protecting sensitive circuits.When the fuse breaks it prevents the flow of electricity to the rest of the circuit.

Overall, both of the labs are pretty simple and straight forward. These labs provide some valuable information to the beginner venturing into electronics. More importantly, learning is always fun.  Baby steps…

Required Materials:
9volt battery
1.5v AA battery (2)
AA battery carrier
Magnifying glass / Jewelers loupe
DMM (Digital Multi-meter) w/leads


It’s been almost two years since my last post on this blog.  Most of the projects I’ve worked were posted on my twitter page located here. However, I am the type of person that cannot leave things “undone” — if you say you’re going to do something, do it. Therefore, I have re-dedicatedreboot my efforts to one of the original purposes of this blog – knock off some of the books that I’ve purchased which are project based and blog about my experience (See list below).

Since my blogging hiatus Charles Platt has released a second edition of Make:Electronics. That said, it makes sense just to simply start with the most recent release and do the projects again. Where applicable I’ll provide my own person ancedotes on what changes were made for the better.

Aside from blogging about some of the books on my “to finish” list. I’ll probably rant/blog about coding, technology, and other personal projects as well.

Now it’s time to get back at it (justification for my wife as to why I have 1000’s of components, tools, and tech all over the place….and why I don’t have enough of each).

These are the books that I plan to blog about in no specific order or reason for their selection other than to finish them (so many more books could have been added and may be added later):

Make: Electronics
Arduino Workshop
Make: More Electronics
Tiny AVR Micro Controller Projects
Analog Synthesizers
Make: AVR Programming
Electronic Circuits for the Evil Genius
JunkBots, BugBots, and bots on wheels|

EC 4 Evil Genius: Project 1 – Lesson 12

Automatic night light
Automatic night light

I finally had some spare cycles this past weekend. This allowed for me to work on 1 of 2 final projects for section one of Electronic Circuits for the Evil Genius. Lesson 12 provides the reader with an opportunity to leverage the knowledge and skills gained thus far. Once the circuit for this project is constructed, it creates an automatic night light that dims in the light and brightens in the dark.

The components used in the circuit include various resistors, a diode, 100k pot, LDR, 5mm LEDs, and a NPN transistor. When attached to a power supply (9v) and with the pot set to around 50k ohms, the LEDs will remain dark/dim in lighted areas and transition to a full glow in a darkened area.

Automatic Night Light
Automatic Night Light

Depending on how much resistance is provided by the pot will determine how much voltage is present in the circuit. Such as, if the pot is set to a low resistance, more voltage is registered, allowing the NPN transistor to be easily activated. Circuit analysis reveals that the LDR is incapable of dumping all of the voltage sent its way.

Although simple in nature, this was an interesting project overall. The knowledge exercised is from the previous sections that dealt with transistor and LDR coverage. This information comes in handy if you attempt to step outside of the suggested components.

For example, the circuit calls for two 5mm LEDs. However, I wanted to use blue LEDs of which require almost double the voltage of red LEDs. Therefore, with the working knowledge of transistors and OHMs Law, I was able to easily determine what type of resistance was necessary to power the two blue LEDs in my circuit.

Automatic Night Light (Testing)
Automatic Night Light (Testing)

This project also required some soldering of components which at least for me is the fun part. The kit associated with the book actually provides you with a ready-to-go PCB. That said, obviously soldering anything worth while is fun; however, experiencing a working circuit when finished is definitely gratifying too.

Lastly, I would recommend keeping the bread boarded circuit as a reference. This way, if you get stuck while putting together the PCB, or if it doesn’t work after the soldering is complete, you have a working physical representation as a reference.

Next up is project #2; post to follow.


EC 4 Evil Genius: Lessons 9, 10, & 11

Electronics Circuits for the Evil Genius lessons #9 and #10 cover the operation of both the NPN and PNP transistors. Specifically speaking the NPN-2N3904 and the PNP-2N3906. The lessons demonstrate how each transistor type reacts when voltage is applied to the base of the transistor.

The demonstration circuit for lesson #9 reveals how the voltage held in a capacitor is used to power the transistor and subsequently allow the LED to turn on.

NPN Circuit Lesson 9
NPN Circuit Lesson 9

Moreover, the base of the transistor requires less power than the load required for the LED; through observation you determine that the capacitor drains the stored voltage very slowly. Further circuit analysis indicates that the capacitor in the circuit is the sole power source for the transistor, and it is the transistor that ultimately provides power to the LED.

Pressing the pushbutton plunger allows the voltage and current to flow through the circuit from the main source. However, when the pushbutton is open, the current and voltage is cutoff resulting in no voltage being sent to the base of the transistor.

I decided to have a little fun and developed a simulated SPICE circuit prior to breadboarding. The video here shows the simulation in progress.

The circuit for lesson #10 demonstrates how the NPN and PNP transistors differ in operation. Once the capacitor is fully charged, voltage is applied to the base of the transistor causing an interruption in current flow. When applying the battery to the circuit the first thing you notice is that the LED is immediately handling a voltage load – the result of a lack of voltage pressure at the base of the transistor.

PNP Circuit Lesson 10
PNP Circuit Lesson 10

The valve of the transistor is open, allowing current to flow from the emitter onward to the collector. Once the plunger of the pushbutton is pressed, voltage is instantly sent to the base of the transistor, closing its internal valve. This blocks the flow of current and causes the capacitor to charge.

However, once the pushbutton is released, the voltage from the capacitor applies pressure on the base of the transistor, closing the valve and restricting current flow from the emitter to the collector.

Next up is lesson #11 which demonstrates the capabilities of the phototransistor, using both the clear and darkened glass versions of the component.

Phototransistor Circuit Lesson 11
Phototransistor Circuit Lesson 11

This lesson is quite interesting as you develop a combination circuit in which have there is an input, processor, and output component.The objective here is to observe how each input component affects the processing component (light spectrum dependent). This circuit however requires that the experiment be conducted away from sunlight. You will also need to print out a disc provided by the text to properly complete the experiment.

The overall purpose is to see how fast or slow the processing component is affected when the (input) light source is blocked. The inputs used are a yellow LED and the clear IR phototransistor. The processors use are an LDR and the dark IR phototransistor.

Up next is the first of two main projects for this section. Putting it all together.

Looking forward to it.

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