Showing posts with label Virginia Jennings. Show all posts
Showing posts with label Virginia Jennings. Show all posts

Wednesday, December 27, 2017

Industrial Electronics- Building a Power Supply

Hey everyone! I am back from a bit of a hiatus due to my engineering classes at Florence Darlington Tech. I am working towards my degree in Electrical Engineering and due to the curiosity from friends on facebook I have decided to share a project I worked on this past semester.

I had to build a power supply and write up a report. Here goes:





To build a power supply, three circuit sections will be needed. Knowledge of transformers, how to build a filtered bridge rectifier, and how to build a voltage regulator is also necessary for this project. A transformer, four 1N4001 zener diodes, a 741 Op Amp, a 2N2222 Transistor, four resistors, a zener diode, and a capacitor will all be needed for this project.

To begin, we started with a step down transformer which was built with a 10:1 or rather a 0.1 turns ratio. This lowers the incoming 120Vac coming from the wall outlet. This particular transformer was center tapped so we could pick either 13vrms or 26vrms. We chose to wire it for 13vrms. Using the formula Vsec=(Nturns)(Vpri) we would come closer to 12vrms however Vrms from the wall can fluctuate within a range so for this report I will stick with 13vrms as it was already established on the transformer. 
In order to know that our transformer was working correctly we need to calculate the peak voltage expected on the oscilloscope screen. Rms=.707(vp) gives us an 18.387Vpp. The oscilloscope verified this by displaying a 18vpp (approximate) sine wave. The sign wave is far from the flat positive voltage we need for DC. 
To start smoothing this sine wave out, we need to build a bridge rectifier. To build the bridge rectifier, we wired together four 1N4001 diodes in this pattern:


We were careful to keep the positives and negative ends of the diodes in the proper direction. At one point, failure to double check our work resulted in the melting and untimely death of a few diodes. The capacitor and the load resistor were chosen to keep the ripple factor low. With a 20KΩ load resistor and a 10uf capacitor our ripple factor turned out to be 4.2%. We could have modified this by switching out the capacitor and resistor and using these formulas until we created the desired ripple factor:

Vp(rect)=Vp(sec)-1.4
Vr(pp)= 1/(fR_LC) x Vp(rect)
VDC= (1- 1/(2fR_LC)) X Vp(rect)
% ripple factor =vr(pp)/ VDC


Connecting the bridge rectifier up to the oscilloscope produced a 18vpp approximate ripple wave to appear on the screen. This is possible due to the diode positioning. During the positive half of the AC sinewave cycle, one pair of diodes conducts the current while the other two are reversed biased. As the negative half of the AC sinewave cycle passes the reversed biased diodes become forward biased and conduct current while the first pair become reversed biased. The process repeats itself bringing all the negative voltage into the positive. Like this:

Adding the capacitor into this circuit creates the sawtooth like ripple. This is created by the capacitor charging during the positive cycles when the diodes are forward biased and discharging as the cycle begins to drop (when the diodes are reversed biased). This created a signal on the oscilloscope like this (exaggerated):


This still isn’t flat DC though. We need to build a voltage regulator to smooth this out. For this we will need a 741 Op Amp, a 2N2222 transistor, three resistors, and a zener diode wired in this configuration:

A zener was chosen to set a voltage of 6.2 volts and R1 was chosen to be 1k to limit the current to the zener and help it maintain a nearly constant 6.2 volts no matter how high or low the incoming voltage goes as long as the current does not exceed the zener limits. In order to create a flat DC voltage this voltage level held by the zener holds the positive input of the op amp at 6.2v creating a reference voltage. Any time Vin decreases or the IL (the load current) increases (due to a decrease in the load resistance), and vice versa, the voltage divider created by R2 and R3 insures that a proportional increase or decrease is applied across the negative input of the op amp.
The difference between the two op amp inputs is amplified by the gain and sent to the base of the transistor. This change in voltage applied to the transistor causes the emitter at Vout to increase until the voltage to the negative op amp input matches the zener input at the positive terminal. This creates a flat DC voltage who’s voltage we can predict by plugging the zener reference value and the chosen R2 and R3 values into the gain formula:

Vout= (1+ R2/R3)Vref    ->      (1+(10k/10k)) x 6.2= 12.4V expected output.
The power supply was completed by connecting the two circuits together by a wire connected in parallel with the capacitor and resistor from the bridge rectifier circuit over to Vin of the voltage regulator:

Connecting the oscilloscope across vout and ground showed that the signal that was once sawtooth in shape was now a flat and solid 12V (approx) DC readout.

To test whether our power supply could handle a variable load we connected an 80k potentiometer at Vout in parallel with R2 and R3. Keeping an eye on the oscilloscope we were able to turn up the resistance to find where the transistor could no longer keep up with the current load (and could no longer keep the voltage at a stable 12volts). As the transistor failed this caused the signal on the oscilloscope to become distorted once again. We unplugged the potentiometer and tested the resistance with a meter to find that the transistor was able to handle the current and keep a steady 12v signal going to the output as long as the resistance of the load stayed under 6K.

Using what was learned in this project it would be possible to replace pieces of the circuit to create a power supply that could operate at higher voltages or tolerate wider load resistance variances. It was very interesting to see firsthand how each part of the circuit worked individually and then how they changed the Ac to Dc once they were connected together. The greatest challenge for me during this project was making sure the diodes in the rectifier were all going in the proper directions and figuring out where everything was in relation to the diagram once we started adding the circuits together. 



  If you have come this far (Holy smokes CONGRATULATIONS!) and have questions (I'm sure you do!)... feel free to leave them in the comments or reach out to me on facebook/twitter ;)

Also, hit the subscribe button because I will be going back to writing sci-fi short stories on my blog as well as entering in updates on my current work in progress which should be out of edition hopefully before May 2018... Just in time for ConCarolinas- I hope.

Meanwhile... run on over to Amazon to get the updated edition of The Alien Mind on kindle for just $0.99 till Jan 1st (afterwhich it returns to $2.99)!

Till next time-> Never stop reaching for the stars and exploring your potential!



Tuesday, August 22, 2017

Solar Eclipse 2017 Pictures From Totality in Columbia SC

Warning... Photo heavy post. Pictures from totality tailgating at the South Carolina State Fairgrounds in Columbia where we witnessed 2.5 minutes of awesome jaw dropping totality!

The clouds tried to have their way-(which made for some interesting views and images) but by the grace of God we were able to have some large chunks of time where the sun was completely clear of the clouds. Totality was completely unmarred by the clouds.

I was able to take pictures of the sun leading up to totality (partial eclipse) both through my telescope and through my phone. I used a pair of solar lense glasses over my phone. For my telescope pictures, my telescope had a solar filter at the top, so I could lay my phone on the eyepiece to photograph what I could see in the telescope. I was impressed at how well the images came out actually (for a phone camera that WASN'T actually mounted to the telescope- I didnt think it would work as well as it did.)

I was able to show my children (ages 6, 13, and 16) sun spots during this time (some of which show up in the pictures. As well as what the solar eclipse looks like through the telescope. We all had glasses so we could view it with our eyes too.

The spectacle of seeing the sky go dark during the day, the stars come out, and the sun disappear except for a thin shiny silver ring was as awesome as one would expect. The air cooled (THANKFULLY) and the atmosphere took on an eerie feeling. Everyone cheered as the last bit of sun hid itself behind the moon.

NOTHING, however, can compare to the shock and awe I felt when I spared a moment to look down into my telescope during totality (AFTER I remembered I needed to take the solar filter off if I expected to see anything during that time lol). The effect through my telescope was so shocking that I exclaimed out loud "Oh my gosh!". I've never been so completely shocked at what I've seen through my telescope until that moment. I've been intrigued in the past, as I've found saturn, or jupiter. But this was a feeling of 100% total amazement. A once in a lifetime sight!

Then I took a moment to tighten my telescope down and begged everyone else to come take a peek. I loved watching everyone else experience that too! My middle son exclaimed "I want to be a scientist now!" We saw at least two 'stars' during this darkened moment, one of which was rumored to be a planet- but I did not have time to confirm that with my telescope or charts.

I went back to take pictures through my telescope by setting my phone on top of the eyepiece right before totality ended. Then... far too soon (wish we had longer) some blessed stranger was broadcasting a radio program that called out a countdown for "glasses on"- which meant I needed to get my face away from my telescope and put that solar filter BACK ON the darn thing before I fried my retinas. Thank you dear stranger!

The ring started to grow larger and our focus was drawn to the shadows returning slowly on the ground as the sun started to come back out once again! Totality cleared and the moon started its recession. We had to fight traffic back out of columbia so we didn't stay for the whole recession but every moment was completely worth the hours of traffic jams afterward!

Oh and one other thank you to the couple that we shared our tent with ;) Our tent was a bit big for the space, so thank you for letting us share it with you! It was awesome getting to hang out with you guys!



More Pictures!

I apologize that these are not in order, I will go back later and put them into order and add more captions.

Dusk Before Totality





Clouds fogging up the shot



some of the red tint is from my phone case reflecting off the solar glasses





Another image through my phone

Pictures through my telescope with solar lens cap




Another through my phone



Through my phone right before totality






Saturday, August 12, 2017

Best Plot Twist- Book Lovers Blog Hop


Tweet: What's our favorite plot twist?
We will share during today's entry in the Book Lover's Blog Hop! https://ctt.ec/2ARZ5+
Today's Book Lover's Blog Hop question for our group of authors is... What's the best plot twist you've ever read?

I LOVE plot twists... though I struggle to rank who's is the best. Anne (in Anne of Green Gables) starts off hating Gilbert Blithe and then by the end of the books she's married to him. This is also done in Pride and Prejudice. Jacob likes Bella who likes Edward is solved by the insinuation that Jacob only ever liked Bella because he was destined to imprint on their daughter born later in the story (Twilight Saga). "Luke, I am your father" (OK that one is a movie).

So what’s the best plot twist you’ve read?






Usually anything by Agatha Christie but I think the one that Got me the most was the one in Cat Amongst the Pigeons. I will not spoil it, but it is one of the least known Poirot stories and the first Agatha Christie I ever read.






Skye Hegyes www.skyehegyes.com
I can’t go into detail of the plot twist without revealing the ending of the book, but Bridge to Terabithia by Katherine Paterson. I was not expecting it, especially in a children’s book. It ripped out my heart and soul, dragged them around, and delivered them back to me broken and bruised, and it was absolutely brilliant.






Laurie Lucking www.landsuncharted.com

I’m going to have to go with a certain plot twist in White Dawn by Sara Baysinger. Her whole Black Tiger series has been full of amazing plot twists, but this one in particular (which I can’t go into because—spoilers!) just blew my mind. Seriously, I was sitting there on my couch in total shock. So crazy and brilliant!





Jebraun Clifford www.jebraunclifford.com

I’d have to say the plot twist in the thriller/mystery Gone Girl. I’d heard there were some unexpected occurrences. But. Wow. Did not expect that one!







Just B. Jordan www.JustBJordan.com 
There have been a lot of fantastic ones out there! The first that comes to my mind is in the Mistborn series. I had to sort through some emotions to come to terms with it! 









One of the first to come to mind is The Kite Runner by Khaled Hosseini which has lots of twists. Pretty much any book by Agatha Christie deserves a mention here too. 









What about you, dear reader? What is your favorite plot twist? Leave your suggestion in the comments below!



Book Lovers Blog Hop Schedule!

(Links are likely to not go live until the date of)

1st August   www.JoLinsdell.com
What are you reading this month? TBR list for August

What’s your favourite genre to read?

Where do you get your books?

Best read of 2017 so far?

Favourite author?

Favourite book cover design?


Preferred book format? (ebook, print, audio)

How do you organise your bookshelves ?

Favourite book to movie adaption?

Most evil villain?

What’s the best plot twist you’ve read?

13th August http://www.cjbrightley.com
Favourite fictional character?

14th August www.JustBJordan.com
Best fictional friendship?

15th August  www.saderena.com/blog
Best book series?

16th August http://www.angelaguidolinauthor.co.uk/blog
Most thought provoking book you’ve read?

17th August  www.tabithacaplinger.com
Top 3 books you think everyone should read

18th August www.skyehegyes.com 
Where do you post your reviews of books you’ve read?

19th August www.landsuncharted.com
What was the last book you gave a 5 star review?

20th August  kmcarrollblog.wordpress.com
Which book do you wish had a sequel?

21st August www.upstreamwriter.blogspot.com 
Which author would you most want to interview and why?

22nd August www.JoLinsdell.com  
How often do you go to the library?

23rd August www.belindabekkers.com
Goodreads challenge/reading goal for this year? On track so far?

24th August www.FabianSpace.com 
Do your family/friends support your reading habit?

25th August  http://theliteraryapothecary.blogspot.com 
Do you enter book giveaways? Last prize you won?

26th August  www.JustBJordan.com 
Name a book that made you cry

27th August  www.jebraunclifford.com 
Do you write as well as read? Do you see yourself being an author in the future?

28th August www.brandypotterbooks.com
When did you get into reading?

29th August www.skyehegyes.com 
What do you do to get out of a reading slump?

30th August www.brandypotterbooks.com
If a genie were to grant you 3 bookish wishes, what would you ask for and why? 

31st August  www.landsuncharted.com
Do you take part in readathons? Why? If yes, which are your favourites? 




Friday, August 11, 2017

Most Evil Villain- Book Lovers Blog Hop


Tweet: Who's voted the most evil villain? Book Bloggers Blog Hop shares our choices! https://ctt.ec/cXf3U+
Today and tomorrow I am participating in the Book Lovers Blog Hop. During this blog hop every host gets to ask a group of authors some reading related questions. Today I'll be asking six authors who they think is the most evil villain. There are links at the end of this post to the rest of the Blog Hop days as well!

It can be pretty hard to nail down just how evil a bad guy is. Most baddies have a reason for doing what they are doing, even in some twisted way. To me, the most evil bad guy is one who takes away the humanity of a person, stripping them of the right to choose, the right to be different. IT in A Wrinkle In Time comes close for me. IT does this by telepathically taking over the victim's mind and forcing them to conform. To top all this off, IT isn't so easy to defeat completely either! (I love Villains that never completely go away!)


The mind is a delicate and valuable thing. The mind is what makes you, well... you. I've seen first hand what damage to a mind can do. Stripping a once hopeful person of all their dreams, making them forget things they once knew, altering their personality so they are no longer who they once were. Villains that toy with their victims mind, manipulating and/or damaging them in any way will always win the Most Evil Victim award in my opinion.

 What do you ladies think?

Brandy Potter - www.brandypotterbooks.com
Defining the most evil villain is hard to do. I think for me it comes down to motivation. For example Moriarty to me isn’t evil, he is just motivated by using his wits to gain what he wants. Then you have Sauron and Voldemort who are absolutely evil, but are they the MOST evil. Perhaps. Voldemort though is a “children’s” evil which fails to portray depravity. Sauron’s evil is masked by the other villains in the story who are concentrated on more. Except for maybe in the Silmarillion, but that is like reading the begats section of the bible for me, so I couldn’t choose him. So I took the road of choosing the character that made my skin crawl and found that it was none other than Jack the Ripper. In Alex Grecian’s The Devil’s Workshop he is portrayed as “Saucy Jack” another name that Scotland Yard gave to the notorious serial killer. He has rules, yes but the way his mind works is chilling… chilling. Coming in a close second is Dr. Peter Teleborian in Stig Larsen’s The Girl that shook The Hornet's Nest. To explain his evil is difficult because I could give away the ending and some would argue Nils Bjurman, Martin Vanger or even Zalachenko were more evil. All of them were chilling, but what Teleborian did to Lisbeth is appalling.

Jo Linsdell www.JoLinsdell.com
There are so many evil villains out there who would easily merit the top spot, but I’m going to go with Ackerman from the Shepherd series by Ethan Cross. Father of Fear (the third book in the series) is when we see just how evil, and twisted this man really is. As far as serial killers go he is definitely at the top of the list with how much he enjoys torturing his victims. What makes him the most evil though is the experimenting he does on his own family. Ackerman Jr really didn’t have much of a chance with a father like that… and although he holds his own ranking in the evil villain list, he’s nothing compared to his father. 


Skye Hegyes www.skyehegyes.com
I think it’s safe to say that the most evil villain in the fictional world is someone everyone can hate with a passion that’s almost holy, and that’s Professor Dolores Umbridge. I mean, how can you not hate the evil little toad of a woman. She was specifically cruel to anyone who did not go along with her exact thoughts of how things should be done. Ugh! Monster!





Belinda Bekkers www.belindabekkers.com
I think Cruella del Vil from The Hundred and One Dalmations and Professor Moriarty from the Sherlock Holmes stories are pretty unbeatable. Pap in the Mosquito Coast is also evil.


Jebraun Clifford www.jebraunclifford.com
Villains should be complicated and three-dimensional. They can’t just be bad because they’re bad. They’ve got to have a good motivation for what they do! To me, a terrible and chilling villain is the Queen in the Hall from Elizabeth Marie Pope’s The Perilous Gard because she doesn’t believe she is evil, she’s only doing what she must to keep her and her faerie folks’ way of life secure. There’s no reasoning with an antagonist like that! 



Just B. Jordan www.JustBJordan.com 
When I hear “most evil villain” my mind instantly goes to Sephiroth from Final Fantasy. (I know, they’re games, not books. Haha) In my childhood Sephiroth was the baddest bad guy out there. My brothers and I would have conversations about how cruelly evil he could be. I think in my mind he will always hold the Most Evil trophy. ;)







I have to go with One from Hexwood by Diana Wynne Jones. He’s this head of the galactic council who has extended his lifespan with various treatments to make sure he never has to pass his rule to anyone else. And he’s ruthlessly destroyed the descendents of the true reigning house, turning them into slaves and worse. No blood is shown, of course, but it’s very implied. I think the implications are so horrible because your mind gets to fill them in. The things he did to one of the heroes … I just shudder, even now. And he does it with a smile and completely friendly logic.


How about you, dear readers? Do you have a Villain that you love to hate? Leave a comment for all of us in the comments section below!



Book Lovers Blog Hop Schedule!

(Links are likely to not go live until the date of)

1st August   www.JoLinsdell.com
What are you reading this month? TBR list for August

What’s your favourite genre to read?

Where do you get your books?

Best read of 2017 so far?

Favourite author?

Favourite book cover design?


Preferred book format? (ebook, print, audio)

How do you organise your bookshelves ?

Favourite book to movie adaption?

Most evil villain?

What’s the best plot twist you’ve read?

13th August http://www.cjbrightley.com
Favourite fictional character?

14th August www.JustBJordan.com
Best fictional friendship?

15th August  www.saderena.com/blog
Best book series?

16th August http://www.angelaguidolinauthor.co.uk/blog
Most thought provoking book you’ve read?

17th August  www.tabithacaplinger.com
Top 3 books you think everyone should read

18th August www.skyehegyes.com 
Where do you post your reviews of books you’ve read?

19th August www.landsuncharted.com
What was the last book you gave a 5 star review?

20th August  kmcarrollblog.wordpress.com
Which book do you wish had a sequel?

21st August www.upstreamwriter.blogspot.com 
Which author would you most want to interview and why?

22nd August www.JoLinsdell.com  
How often do you go to the library?

23rd August www.belindabekkers.com
Goodreads challenge/reading goal for this year? On track so far?

24th August www.FabianSpace.com 
Do your family/friends support your reading habit?

25th August  http://theliteraryapothecary.blogspot.com 
Do you enter book giveaways? Last prize you won?

26th August  www.JustBJordan.com 
Name a book that made you cry

27th August  www.jebraunclifford.com 
Do you write as well as read? Do you see yourself being an author in the future?

28th August www.brandypotterbooks.com
When did you get into reading?

29th August www.skyehegyes.com 
What do you do to get out of a reading slump?

30th August www.brandypotterbooks.com
If a genie were to grant you 3 bookish wishes, what would you ask for and why? 

31st August  www.landsuncharted.com
Do you take part in readathons? Why? If yes, which are your favourites?