Make: Electronics

Errata for Make: Electronics

Submit your own errata for this product.

The errata list is a list of errors and their corrections that were found after the product was released.

The following errata were submitted by our customers and have not yet been approved or disproved by the author or editor. They solely represent the opinion of the customer.

Color Key: Serious technical mistake Minor technical mistake Language or formatting error Typo Question Note Update

Version Location Description Submitted by Date submitted
, Other Digital Version Page ONxNuGNDKh

8ceOfn <a href="">cmgynchhjxko</a>, [url=]hwueyovjjjrc[/url], [link=]tcginkvjzgpg[/link],

fwncttlx  Nov 30, 2016 
Printed Page 32
last paragraph

than -> that

Bogdan Barbu  Apr 04, 2015 
Printed Page 36, 37
(pg. 36, right column, 3rd paragraph), (pg. 37, 2nd paragraph)

Wattage, which measures power, is erroneously said to measure work.

Bogdan Barbu  Apr 06, 2015 
Printed Page 45
2nd paragraph (right under heading "Testing"

The phrase between brackets "(the resistor, in this case)" should read "(the switch, in this case)" in order to match up with figures 2-17, 2-18 and 2-22.

Ron Bonne  Jun 20, 2015 
PDF Page 50
Fig 2-35

The LED in figure 2-35 appears to have the triangle pointing from negative to positive, but the text says it should point from positive to negative?

2009 Version of the PDF

John Parker  Jul 12, 2015 
Printed Page 60
2nd paragraph just following fig. 2-64

Statement: "the contacts in their relaxed state feed power to the lefthand LED."

In above statement, it is not clearly stated whether "lefthand LED" refers to fig. 2-64 (schematic which correctly indicates the lefthand LED), or fig. 2-63 (physical representation in which the RIGHTHAND LED is the one which is fed power in the relaxed state).

John Lindstrom  Dec 24, 2014 
PDF Page 77
Second equation under the section: "Background: The Time Constant"

The calculation of the time constant is wrong.
TC = 1.000 / 0.001 should be TC = 1.000 * 0.001
Also, it's confusing to abbreviate the time constant as TC, since it can be interpreted as the time (T) multiplied by the capacitance (C).

Anonymous  Mar 22, 2019 
Printed Page 147
Figure 4-11


In figure 4-11, between pin 3 of the 555 timer and the - side of the circuit, you have first the 470 ohm resistor followed by the LED, it is the other way around (LED first) in figures 4-12, 4-13, 4-14. I am sure people can figure it out but just as a FYI to keep things consistant.

Thank you,

Arnaud Decornez  Mar 20, 2019 
Printed Page 152
Figure 4-19


Very very minor graphical error. The blue wire coming out of pin 6 of the 555 going into the - side of the circuit is not drawn correctly. It should be angled up or down in order to connect to the - bus. The graph draws the wire as connecting to a point where there is actually no hole for the - bus on the breadboard. By this stage, readers will have obviously figured that out :-). Just an FYI if you want to keep things clean.

Arnaud Decornez  Mar 22, 2019 
Printed Page 186
Figure 4-72

The first horizontal wire connecting to the negative bus on the breadboard just below where we connect the power source should not have been grayed-out. It is a new wire which grounds pin 1 for the new 555 chip we are adding to the breadboard.

Arnaud Decornez  Mar 31, 2019 
Printed Page 200
Questions, 1st paragraph

Many have had trouble getting the relay to activate due to insufficient voltage. This paragraph says that the reason for using a 555 was to deliver enough voltage. However, according to Charles' Encyclopedia, Vol 2, the voltage on the output pin will be up to 1.7V less than the input. Since input is 5V, and that's what the relay needs, how can that be? In my case, I'm giving 4.86V to pin 8 and getting 3..77 volts on pin 3. Is this an error or am I missing something?

Virgil Machine  Mar 13, 2015 
Printed Page 201
Figure 4-84

NOTE: This also appears to affect Figure 4-83 on page 198, but i think most people will build the circuit based on Figure 4-84 on page 201.

The relay i am using is from the Radio Shack parts kit 2 and is an HFD2/005-M-L2 Latching relay.

I built this circuit as it appears in 4-84 and could not get it to flop my latching relay after entering the unlock code. I knew the relay was working because as a test i switched the output of my # key back and forth between the two different relay inputs and this would successfully flop the relay back and forth.

After trying a lot of suggestions i found online unsuccessfully, i decided to instead check the incoming voltage at pin 8 of the 555 timer. Sure enough the problem was rooted here (or at least as far as my troubleshooting skills could take me :-)). The incoming voltage was around 3.6 V which is seen as the supply voltage for the 555. The resulting output from pin 3 was around 1.8 V if memory serves correct. I may be slightly off on these but the simple explanation is that there wasn't enough voltage coming into the 555 to then in turn trigger the relay. My guess is that it has to do with the fact that all three chips and the LED and 330 ohm resistor share the same positive connection.

My simple solution to this problem was to remove the connection from the * key to pin 8 of the 555 and instead connect pin 8 of the 555 timer directly to positive. This allowed the circuit to work except that the LED connected to the * key would stay on constant. This part is really unclear to me. However, my solution to this last issue was to just remove the connections from the * key to pin 14 on both the 7408 and 7404 chips. For both of these chips, i just connected them directly to the positive power rail as i did with the 555. After making these three changes (connecting all three chips directly to the positive power rail instead of to the * key circuit) the circuit worked exactly as described. I was getting a full 5 volts to pin 8 of the 555 and the pin 3 output was now sufficient to flop the relay.

So the only real change to the schematic in this case would be to take all three of the chip positive pin connections (which are connected together in the schematic) and connect them directly to the positive power rail instead of the * key circuit.

Chris Coffin  Mar 14, 2015 
Printed Page 203
3rd and 4th paragraphs that deal with buttons C D & E

I believe the author meant buttons B C & D instead of buttons C D & E. Based on the schematics button E looks like it brings the left-hand side of the AND gate into a high state and is not involved with bringing the right-hand side of the 1st AND gate into a low state like buttons B C & D. To be clarified / confirmed.

Arnaud Decornez  Apr 01, 2019 
Printed Page 214
Bullets under 6th paragraph

I know it's only used in the enhancement section, but it would be nice if the 74LS06 Inverter were listed here (perhaps with a note that it's needed only if the reader follows through with the enhancement). After all, we bought them because Charles said to on p150.

Virgil Machine  Mar 23, 2015 
Printed Page 217

There is no mention of what the function of Clock Input B is (74LS92 pin 1), or why it is connected to Binary input A (pin 3). I've looked at the datasheet, and it's not clear there either. I don't see this chip in either volume of Charles' Encyclopedia, but sections in Vol2 on roughly similar chips don't mention it either.

Shouldn't this book explain this?

Virgil Machine  Mar 23, 2015 
PDF Page 270
4th paragraph

It says "allways wear gloves...when using a table saw".
But it is actually very unsafe to wear gloves with a table saw: the glove can get caught in the saw and do a lot of damage. So please remove this part of the sentence. You can Google the the opinion about this ;-)

Bert Super  Jul 27, 2015 
Printed Page 295

I resisted doing experiments 34 and 25 because there was no mention in the shopping list on p.227ff, nor on this page of the programming cable. It seems dishonest to hype the inexpensive $5 picaxe and say oh by the way you need a $20 cable.

However, this is a learning book, and after a few months of simmering I went back and found directions for making a serial cable at

I have a 14 year old Windows XP machine with serial ports, so I fired it up and downloaded the picaxe software. I had to buy a DB9F connector ($3) but that's all. If I hadn't had the old computer I could have bought a PCI serial card for about $4 and installed in in my main desktop (Windows 10).

I really think that Charles missed some "learning by discovery" here by dismissing this option (top of p.296). Makers should be given the opportunity to make.

But, I still love the book!

Virgil machine  Apr 03, 2016 
PDF Page 313
Figure 5-147

On page 311 it says that the experiment will use the same type of keypad recommended in Experiment 20. However, in figure 5-147 we see that the "common" wire in the keypad no longer applies to the asterisk and pound keys, which might confuse the reader who is attempting to build the circuit.
This will require a modification of the keypad or an alternative approach.

Anonymous  Jun 02, 2016 
Printed Page 317
only paragraph under header "Heat-Shrink Tubing"

lists "hom, har, and nor" as hardware suppliers. I think these might be author's placeholder words.

Similar error (maybe) on same page at end of paragraph under "Project Boxes" - "ada and spk" don't seem to be real suppliers.

Similar error (maybe) near end of previous page, 316 - at end of paragraph header "Solder", lists suppliers "all, elg, jam, ada, amz, and spk".

None of the seeming nonsense words are capitalized, so they doubly don't seem like real companies.


Anonymous  Aug 15, 2016