EEVblog#160 – 555 Timer Easter Egg? - Page 1
Forum section: electronics / general

author: metalphreak
author_rank: Frequent Contributor
timestamp: April 01, 2011, 02:25:06 pm
content: Hey Dave,Can confirm the same thing happens with a SGS THOMSON SOIC package 555!Easter Eggs in everything. It's crazy.

author: dimlow
author_rank: Frequent Contributor
timestamp: April 01, 2011, 03:37:35 pm
content: Quote from: metalphreak on April 01, 2011, 02:25:06 pmYep confirmed it TODAY!

author: firewalker
author_rank: Super Contributor
timestamp: April 01, 2011, 03:48:30 pm
content: I love Easter Eggs (on every date :p). In one of my projects containing an alphanumeretic lcd the "Easter Egg" was instructions for obtaining the source code.

author: Zero999
author_rank: Super Contributor
timestamp: April 01, 2011, 06:30:24 pm
content: Interesting.Looking at the internal schematic of the 555 doesn't explain it. If it's deliberate, then there's more to the schematic than the datasheet gives, if it's a coincidence there's some parasitic element inside the IC which is to blame.

author: oPossum
author_rank: Super Contributor
timestamp: April 01, 2011, 07:31:46 pm
content: It works with National LM7555 (CMOS version), but only at a supply voltage of 7.555 volts.

author: Zero999
author_rank: Super Contributor
timestamp: April 01, 2011, 07:33:55 pm
content: Quote from: oPossum on April 01, 2011, 07:31:46 pmLol, you can't be serious. Perhaps Dave should test this?

author: buffalo960
author_rank: Contributor
timestamp: April 01, 2011, 07:44:58 pm
content: I think I should show this video to my digital circuits class today

author: Strube09
author_rank: Regular Contributor
timestamp: April 01, 2011, 07:57:07 pm
content: Yep,But it doesn't seem very stable on my end.... Will have to test again tomorrow to see if it works again

author: oPossum
author_rank: Super Contributor
timestamp: April 01, 2011, 08:29:15 pm
content: Quote from: Hero999 on April 01, 2011, 07:33:55 pmI am serious. And don't call me Shirley.

author: Lance
author_rank: Frequent Contributor
timestamp: April 01, 2011, 10:50:28 pm
content: Wow, this is pretty cool! I'll see if I can give it a try.

author: EEVblog
author_rank: Unknown
timestamp: April 01, 2011, 11:16:54 pm
content: Quote from: Hero999 on April 01, 2011, 06:30:24 pmHans was a clever designer, I'm sure it's very subtle...Dave.

author: EEVblog
author_rank: Unknown
timestamp: April 01, 2011, 11:18:48 pm
content: Quote from: oPossum on April 01, 2011, 07:31:46 pmAwesome, will have to try it.Hans was bought back to design the 7555, so makes sense he put something in that too.Dave.

author: Lance
author_rank: Frequent Contributor
timestamp: April 02, 2011, 03:51:08 am
content: I wonder what would happen if you made a 555 out of discrete components.

author: steaky1212
author_rank: Regular Contributor
timestamp: April 02, 2011, 07:45:23 am
content: Am I the only one that thinks April Fools??

author: Zero999
author_rank: Super Contributor
timestamp: April 02, 2011, 08:13:33 am
content: Quote from: steaky1212 on April 02, 2011, 07:45:23 amOf course, lol, I can't believe we fell for it.

author: tnt
author_rank: Regular Contributor
timestamp: April 02, 2011, 08:30:13 am
content: A question would be "how did he do it ?".I guess the scope leads don't connect to the breadboard at all but to some signal generator with a modulation input ?

author: Zero999
author_rank: Super Contributor
timestamp: April 02, 2011, 09:25:30 am
content: What didn't make sense to me was the frequency seemed to be changing slightly, yet he detected the modulation using a simple low pass filter which shouldn't work, so it should've been obvious something was a miss.

author: EEVblog
author_rank: Unknown
timestamp: April 02, 2011, 09:43:47 am
content: Quote from: tnt on April 02, 2011, 08:30:13 amI can assure you, the scope leads were connected directly to the 555 as explained.Dave.

author: Zero999
author_rank: Super Contributor
timestamp: April 02, 2011, 10:33:53 am
content: The circuit doesn't match the schematic.The pot is really 200R rather than 500R and then there's all those resistors connected in parallel.The pot should also never be allowed to go too low otherwise it'll burn out the discharge transistor in pin 7 so there should be a fixed resistor in series with it.

author: neoone
author_rank: Regular Contributor
timestamp: April 02, 2011, 12:04:19 pm
content: Quote from: EEVblog on April 02, 2011, 09:43:47 amIs there a prize for figuring out how you did it?

author: EEVblog
author_rank: Unknown
timestamp: April 02, 2011, 12:53:12 pm
content: It matches.As mentioned, the values are approximate.Only found a 200R pot in my kit, so used a series resistor as well.The 1k5 is made with 3 resistors to tweak the value so I could get the range needed.No trickery in the resistors at all.Dave.

author: ShiftPlusOne
author_rank: Regular Contributor
timestamp: April 02, 2011, 03:42:29 pm
content: I hope there's a reveal coming up then.

author: neoone
author_rank: Regular Contributor
timestamp: April 02, 2011, 06:32:56 pm
content: and that's a normal 555 timer not some uC in DIP8 ?I don't suppose Dave did something with Agilent scope heh.

author: ShiftPlusOne
author_rank: Regular Contributor
timestamp: April 02, 2011, 07:49:18 pm
content: Not just an engineer, but a magician also apparently.

author: EEVblog
author_rank: Unknown
timestamp: April 02, 2011, 09:55:41 pm
content: Quote from: neoone on April 02, 2011, 06:32:56 pmYep, brand new bog standard National 555 timer.Try harder!Bueller?, Bueller?Dave.

author: AdShea
author_rank: Contributor
timestamp: April 03, 2011, 03:28:53 am
content: Are you putting the signal in through the power supply?

author: Lance
author_rank: Frequent Contributor
timestamp: April 03, 2011, 05:37:39 am
content: I posted this in another forum...the response is skeptical.http://www.physicsforums.com/showthread.php?p=3226304#post3226304

author: ShiftPlusOne
author_rank: Regular Contributor
timestamp: April 03, 2011, 05:52:31 am
content: Doesn't seem they are being skeptical as much as they are just being asshats.

author: firewalker
author_rank: Super Contributor
timestamp: April 03, 2011, 08:06:02 am
content: Quote from: AdShea on April 03, 2011, 03:28:53 amDave used batteries also.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: April 03, 2011, 08:35:28 am
content: Take a look Here

author: neoone
author_rank: Regular Contributor
timestamp: April 03, 2011, 09:25:44 am
content: Could you explain some things? Are you saying there is not only 55.5kHz but also it's harmonics at 111kHz ? sorry but I couldn't understand few words on your video probably due to accentOr maybe you wanted to show Us that there is something injected to the signal through a ground loop of the probes ?

author: FreeThinker
author_rank: Frequent Contributor
timestamp: April 03, 2011, 09:28:23 am
content: It's not my videoJust found it on YouTube.

author: neoone
author_rank: Regular Contributor
timestamp: April 03, 2011, 09:56:42 am
content: oh, OKAny ideas then ?

author: FreeThinker
author_rank: Frequent Contributor
timestamp: April 03, 2011, 10:41:48 am
content: As I understand it he says that it also modulates at 111hz at 111khz carrier ie twice Daves frequency. 55khz could be the fundamental frequency or another harmonic, still not convinced that there isn't some sneaky business going on but it's beyond me, just have to wait for Dave to come clean or someone to crack it........watch this space

author: tnt
author_rank: Regular Contributor
timestamp: April 03, 2011, 10:48:14 am
content: Quote from the video author found on youbtube :Quote

author: FreeThinker
author_rank: Frequent Contributor
timestamp: April 03, 2011, 02:07:28 pm
content: Perhaps Daves April Fool will get to be as famous as thishttp://news.bbc.co.uk/onthisday/hi/dates/stories/april/1/newsid_2819000/2819261.stm

author: Zero999
author_rank: Super Contributor
timestamp: April 03, 2011, 03:36:01 pm
content: Quote from: FreeThinker on April 03, 2011, 10:41:48 amThat makes sense, so it/s not just the frequency which changes, varying the voltage on pin 5 also varies the duty cycle which can be detected with a simple RC filter.

author: Lance
author_rank: Frequent Contributor
timestamp: April 03, 2011, 04:43:06 pm
content: Quote from: ShiftPlusOne on April 03, 2011, 05:52:31 amI found this slightly amusing:One person: I want to know what brand solder flux that guy is using and how much he's inhaling.Another person: Holy jeez, I know! He is rather obnoxious.

author: ziq8tsi
author_rank: Regular Contributor
timestamp: April 03, 2011, 06:35:49 pm
content: I do not detect any extra wires going to the breadboard, but I notice that Dave is working on top of a thin mat. So I am going to suggest a loop antenna underneath transmitting the 55.5Hz signal. With the cap missing, the breadboard spring would need to pick up well enough to put a few tens of mV swing onto the control pin (which is connected to the 5k-5k divider internally).

author: DrGeoff
author_rank: Frequent Contributor
timestamp: April 04, 2011, 03:13:46 am
content: Dave must be reading too much of 'Harmonic 695'! Maybe time to get out our tin foil hats

author: EEVblog
author_rank: Unknown
timestamp: April 04, 2011, 04:06:19 am
content: Quote from: Lance on April 03, 2011, 04:43:06 pmI get comments like that all the time!They wouldn't now what enthusiasm is if it bit them on the arse.Dave.

author: itstemo1
author_rank: Newbie
timestamp: April 04, 2011, 06:48:14 am
content: Can we get a Detail Sketch (all the values and where you took your measurement).I am new to electronics and just got myself a oscilloscope and I can't get the same wave form as you did. Sorry n00by speaking.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: April 04, 2011, 04:13:30 pm
content: Very interesting 1/2 second or so at about 2:15 are those wires to the bottom of the bread board? aerial?

author: Lance
author_rank: Frequent Contributor
timestamp: April 04, 2011, 04:34:01 pm
content: Quote from: EEVblog on April 04, 2011, 04:06:19 amHa! You said arse...

author: steaky1212
author_rank: Regular Contributor
timestamp: April 04, 2011, 04:55:22 pm
content: Quote from: FreeThinker on April 04, 2011, 04:13:30 pmhaha, busted i think

author: neoone
author_rank: Regular Contributor
timestamp: April 04, 2011, 09:25:41 pm
content: You meant that ?

author: FreeThinker
author_rank: Frequent Contributor
timestamp: April 04, 2011, 10:04:52 pm
content: Yep! Looks suspiciously like an aerial coil or a pair of wires to me, could be just a wire clipping but the breadboard seems to be stood on some sort of mat. Makes me suspect some sort of magnetic loop or rfid type of thing (running out of ideas so any straw looks good)

author: insurgent
author_rank: Regular Contributor
timestamp: April 06, 2011, 04:38:51 am
content: Just listened to the latest AmpHour. Definitely sounds like you nailed it FreeThinker!Good thing Dave doesn't work for the CIA/NSA/FBI.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: April 06, 2011, 08:36:27 pm
content: Yahhh! Do I get a prize? Lol. .......perhaps a Tshirt 'I Sussed Dave 04/2011' (With my luck it would be one of those bloody lcd's he's trying to shift) Looking forward to to the reveal to find out exactly how it was done

author: Mr J
author_rank: Regular Contributor
timestamp: April 08, 2011, 01:16:21 am
content: Check out my video responsewww.n1ir.com. Breadboarded multiple times multiple chips and still could not get it to oscillate? Watch video 7 and see me build it up. Might be a ground loop or picking up the mains (50 hz) all I can think of?N1IR, Mr J.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: April 08, 2011, 09:58:50 am
content: Reveal has been posted. Nice one!

author: Zero999
author_rank: Super Contributor
timestamp: April 08, 2011, 04:07:42 pm
content: Quote from: EEVblog on April 04, 2011, 04:06:19 amGoing by the comments, they also lack a sense of humour.