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According to Pete - October 3, 2011

Check out this month's "According to Pete."

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I failed to mention the winner of the caption contest this morning - apologies all around! But here you have it - the winner of last week's SparkFun Caption contest.

Holy mackerel! This isn't what I meant by driving me by school.

Thank you, Mulvane, for your winning contribution - we'll get in touch to get you your prize (a SparkFun Inventor's Kit for Arduino). Also, thanks to everyone who participated. We'll do another contest in the near future. Now on to the post...

Fall is officially here and with the new month comes a new "According to Pete." If you're new to the series, it works like this - on the first Monday of the month, our Director of Engineering Pete Dokter chooses one embedded electronics topic and breaks it down to easily digestible bits of goodness. In the past, Pete has talked about things like diodes and transistors, OpAmps, and the innards of his workspace amplifier. This week, Pete's coming at you with a bit about 555 Timers. Check it out:

Well, there you have it. Leave any questions, comments, or ideas for future "According to Pete" videos in the comments. We'll be back with your next visit with Pete in a month. Cheers!

Comments 36 comments

  • Do you guys plan on releasing these on DVD? Would be great for those of us who live in the middle of nowhere and only get satellite internet.

    • I just moved from the land of unlimited super broadband to the middle of nowhere. Let's just see how much watching that video cost me download wise on my Satellite Internet connection... Hmm. 12% of my 400 Meg "Daily Allotment". That's pretty harsh! Had I opted for the standard 200 Megs, that would have been a quarter of the day's allotment.
      Heh. Satellite Internet. It's slogan should be "Well, it's better than dialup!"

      • Exactly! We used to have unlimited fiber optic internet. Talk about 15mb/s download and no bandwidth restrictions. Then we moved to the middle of no-where 10miles from town and the only thing we get is dial-up or satellite. I'm not sure if it is better than dial-up. At least with dial-up they don't cap your download limit. Most of the time it is barely faster than dial-up so who knows.
        The only way I can watch these videos is to stay up to 2am and watch them in the "unlimited period." Which really screws with my sleep schedule. It would be really nice to have a DVD set of these videos for this reason.

        • Well, to be fair, it IS better than dial up. It's always on, it mostly works. It downloads much faster than dialup, but with the savagely draconian "Daily Allotment" to deal with.
          You gotta download the "Drop Box" tool that allows you to schedule downloads for the free time (Between 1am and 7am EST)
          As such, it would be nice if videos would offer a download link in addition to the streaming link.
          Streaming video is a no-go for Satellite Internet users.

  • My understanding also is that the three resistors are 5K

  • love these!!

  • It would be nice to have an "According to Pete" about Inductors (and perhaps capacitors at the same time).

  • In the astable section, the equation for frequency is incorrect. There is a 2 missing in front of R2. As stated the frequency is 1/Th which is obviously incorrect.

  • Are those kids in the pictures your kids?
    They're cute!

  • Hay I saw that car at the Fort Wayne 1st annual Maker Fair, pretty cool.
    btw, what happened to the Gravatars? I keep checking it in my profile but it never shows up.

  • That really is an annoying chip.

  • Yes! the awaited 555 talk. I will finally know how to properly use the 15 pcs I have lying around before I went programmable....ah those were the (HARD) days. So many passives.

  • The "control" pin can be used for really cool things. Like put a diode to allow only positive or negative voltages and smooth it out with a cap feed that into the control pin. Then put an op amp with a microphone on the diode. This will allow you to use your voice to modulate say a server motor for simulating speech on a robot. Or it could be prerecorded sound.
    Another use is pwm in a switching power supply. I was actually looking through a switching power supply book today and saw them using the 555 for controlling the transistor in the power supply.
    So, there you have it, 2 uses that I have used/seen.
    Excellent explanation of the 555 timer. It is always nice to see a live human explain things rather than just reading a manual.

  • 2 thumbs up.
    It's great when someone who's excited and interested in something talks about it.
    Nice job Pete - these ATP videos achieve more in 5 minutes than my EE lectures used to achieve in 45 minutes.
    Keep these coming please

  • FYI, the frequency is 1/Ln(2)C1(R1+2*R2) unless you bypass R2 with a diode -- this is really important if you're trying to control PWM with a duty cycle of 50% or less.
    (I'm sure you already know this and simply forgot to add either the diode or the second R2 value, but I still have a head-shaped dent in my desk from when I first tried to make a PWM circuit and didn't know that the diode was necessary, and I wanted to save someone else the aggravation)
    Also, I've seen a 555 charging a capacitor which was also connected to a second 555's control pin -- this created an oscillating frequency and a really wicked flame-like flicker effect in an LED. I think that one of the engineer's mini notebooks has the circuit.

  • Man. It seems like every video I have seen regarding the 555 timer always ends with someone rocking out to a tone generator xD

  • Mon-no-stay-bleh xD

  • My arch nemesis, great.

  • If you're taking requests, how about Mars, the Bringer of War?

    • Holst? My kids LOVE that song! But I think I'd need 2 or 3 generators to pull it off right. Though I 'spose you'd get it from the rhythm...

  • Timely! I was just having issues with a 555 circuit I am working on. How did you know Pete?
    Edit: Turns out you CAN fry 555s. Circuit works much better with a working chip.

  • Sunshine of your love /
    Over the Rainbow /
    Don't you want me /
    Sunshine of your love (again)
    Also, put in a potentiometer as R1/R2 on your astable and you get a fixed-frequency (-ish) oscillator with variable duty cycle (PWM).

    • The resistor value is easy to measurer with a multi meter if you like really really like to know the value. Unfortunately I don’t have a 555 :( epic fail I know.
      And if I need a 50/50 duty cycle I use a resistor the same value as R1 in series with the discharge pin. But then your equations are not correct and you need to find the correct new ones.

    • So much for the 5K resistor myth.

      • Dude Talk about Flip Flops! LOL.
        OMG, Your friends with Jimmie P Rodgers!
        Tell him I love my open heart kit!

    • Well there went a good half-hour of my work day, good read.
      It's incredible that people used to hand-draft those layouts.

  • I haven't even watched this yet, but I have to say that the "According to Pete" series has to be my favorite of all the videos/articles that Sparkfun puts out. I've watched each one at least twice, and even set up little breadboard experiments to go along with the videos while I watch to better understand.
    Keep up the awesome videos, they are very helpful,
    Travis, UCF Junior EE undergrad.

  • Pete! Cool shirt!
    That is all? Well not quite. I think the resistors in the 555 are 5KΩ, hence the name 555.

    • I agree with you, the little schematic on the back of the RadioShack 555 box says 5k for the resistors so unless RadioShack lied, it should be 5k

  • Such videos (According-to-Pete) are very useful and appreciated. I know the preparation demands some work (and you are busy people) but nevertheless, I would suggest two videos per month.
    Thanks anyway

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