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EEVblog => EEVblog Specific => Topic started by: metalphreak on April 02, 2011, 01:25:06 am

Title: EEVblog#160 – 555 Timer Easter Egg?
Post by: metalphreak on April 02, 2011, 01:25:06 am
Hey Dave,

Can confirm the same thing happens with a SGS THOMSON SOIC package 555!

Easter Eggs in everything. It's crazy.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: dimlow on April 02, 2011, 02:37:35 am
Hey Dave,

Can confirm the same thing happens with a SGS THOMSON SOIC package 555!

Easter Eggs in everything. It's crazy.

Yep confirmed it TODAY!
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: firewalker on April 02, 2011, 02:48:30 am
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.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Hero999 on April 02, 2011, 05:30:24 am
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.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: oPossum on April 02, 2011, 06:31:46 am
It works with National LM7555 (CMOS version), but only at a supply voltage of 7.555 volts.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Hero999 on April 02, 2011, 06:33:55 am
It works with National LM7555 (CMOS version), but only at a supply voltage of 7.555 volts.
Lol, you can't be serious. Perhaps Dave should test this?
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: buffalo960 on April 02, 2011, 06:44:58 am
I think I should show this video to my digital circuits class today ;)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Strube09 on April 02, 2011, 06:57:07 am
Yep,

But it doesn't seem very stable on my end.... Will have to test again tomorrow to see if it works again  ;)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: oPossum on April 02, 2011, 07:29:15 am
Lol, surely you can't be serious.

I am serious. And don't call me Shirley.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Lance on April 02, 2011, 09:50:28 am
Wow, this is pretty cool! I'll see if I can give it a try.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: EEVblog on April 02, 2011, 10:16:54 am
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.

Hans was a clever designer, I'm sure it's very subtle...

Dave.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: EEVblog on April 02, 2011, 10:18:48 am
It works with National LM7555 (CMOS version), but only at a supply voltage of 7.555 volts.

Awesome, will have to try it.
Hans was bought back to design the 7555, so makes sense he put something in that too.

Dave.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Lance on April 02, 2011, 02:51:08 pm
I wonder what would happen if you made a 555 out of discrete components.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: steaky1212 on April 02, 2011, 06:45:23 pm
Am I the only one that thinks April Fools??
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Hero999 on April 02, 2011, 07:13:33 pm
Am I the only one that thinks April Fools??
Of course, lol, I can't believe we fell for it.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: tnt on April 02, 2011, 07:30:13 pm
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 ?
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Hero999 on April 02, 2011, 08:25:30 pm
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.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: EEVblog on April 02, 2011, 08:43:47 pm
I guess the scope leads don't connect to the breadboard at all but to some signal generator with a modulation input ?

I can assure you, the scope leads were connected directly to the 555 as explained.

Dave.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Hero999 on April 02, 2011, 09:33:53 pm
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.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: neoone on April 02, 2011, 11:04:19 pm
I can assure you, the scope leads were connected directly to the 555 as explained.

Dave.
Is there a prize for figuring out how you did it? ;)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: EEVblog on April 02, 2011, 11:53:12 pm
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.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: ShiftPlusOne on April 03, 2011, 02:42:29 am
I hope there's a reveal coming up then.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: neoone on April 03, 2011, 04:32:56 am
and that's a normal 555 timer not some uC in DIP8 ? ;) I don't suppose Dave did something with Agilent scope heh. 
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: ShiftPlusOne on April 03, 2011, 05:49:18 am
Not just an engineer, but a magician also apparently.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: EEVblog on April 03, 2011, 07:55:41 am
and that's a normal 555 timer not some uC in DIP8 ? ;) I don't suppose Dave did something with Agilent scope heh. 

Yep, brand new bog standard National 555 timer.
Try harder!

Bueller?, Bueller?

Dave.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: AdShea on April 03, 2011, 01:28:53 pm
Are you putting the signal in through the power supply?
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Lance on April 03, 2011, 03:37:39 pm
I posted this in another forum...the response is skeptical.

http://www.physicsforums.com/showthread.php?p=3226304#post3226304 (http://www.physicsforums.com/showthread.php?p=3226304#post3226304)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: ShiftPlusOne on April 03, 2011, 03:52:31 pm
Doesn't seem they are being skeptical as much as they are just being asshats.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: firewalker on April 03, 2011, 06:06:02 pm
Are you putting the signal in through the power supply?

Dave used batteries also.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: FreeThinker on April 03, 2011, 06:35:28 pm
Take a look Here
555 Easter Egg and Ground Loops (http://www.youtube.com/watch?v=BJNhVb_JO0U#ws)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: neoone on April 03, 2011, 07:25:44 pm
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 accent ;) Or maybe you wanted to show Us that there is something injected to the signal through a ground loop of the probes ?
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: FreeThinker on April 03, 2011, 07:28:23 pm
It's not my video  :) Just found it on YouTube.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: neoone on April 03, 2011, 07:56:42 pm
oh, OK :) Any ideas then ?
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: FreeThinker on April 03, 2011, 08:41:48 pm
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 ;)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: tnt on April 03, 2011, 08:48:14 pm
Quote from the video author found on youbtube :

Quote
If he has done it like me, than there is a hidden wire to the control voltage pin, from an external sine generator, adjusting the level with another? pot outside the camera view. Of course, if you add a capacitor from this input to ground, the modulating signal will be shorted :-)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: FreeThinker on April 04, 2011, 12:07:28 am
Perhaps Daves April Fool will get to be as famous as this
http://news.bbc.co.uk/onthisday/hi/dates/stories/april/1/newsid_2819000/2819261.stm (http://news.bbc.co.uk/onthisday/hi/dates/stories/april/1/newsid_2819000/2819261.stm)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Hero999 on April 04, 2011, 01:36:01 am
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 ;)
That 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.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Lance on April 04, 2011, 02:43:06 am
Doesn't seem they are being skeptical as much as they are just being asshats.
I 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.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: ziq8tsi on April 04, 2011, 04:35:49 am

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).
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: DrGeoff on April 04, 2011, 01:13:46 pm
Dave must be reading too much of 'Harmonic 695'! Maybe time to get out our tin foil hats :)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: EEVblog on April 04, 2011, 02:06:19 pm
Doesn't seem they are being skeptical as much as they are just being asshats.
I 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.

I get comments like that all the time!
They wouldn't now what enthusiasm is if it bit them on the arse.

Dave.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: itstemo1 on April 04, 2011, 04:48:14 pm
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.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: FreeThinker on April 05, 2011, 02:13:30 am
Very interesting 1/2 second or so at about 2:15 are those wires to the bottom of the bread board? aerial?
http://www.youtube.com/watch?v=XZ4r8Rc5aus&feature=player_embedded#t=135s (http://www.youtube.com/watch?v=XZ4r8Rc5aus&feature=player_embedded#t=135s)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Lance on April 05, 2011, 02:34:01 am
Doesn't seem they are being skeptical as much as they are just being asshats.
I 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.

I get comments like that all the time!
They wouldn't now what enthusiasm is if it bit them on the arse.

Dave.
Ha! You said arse...
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: steaky1212 on April 05, 2011, 02:55:22 am
Very interesting 1/2 second or so at about 2:15 are those wires to the bottom of the bread board? aerial?

haha, busted i think
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: neoone on April 05, 2011, 07:25:41 am
You meant that ?
(http://img839.imageshack.us/img839/3677/dave555.jpg) (http://img839.imageshack.us/i/dave555.jpg/)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: FreeThinker on April 05, 2011, 08:04:52 am
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  ;D)
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: insurgent on April 06, 2011, 02:38:51 pm
Just listened to the latest AmpHour. Definitely sounds like you nailed it FreeThinker!

Good thing Dave doesn't work for the CIA/NSA/FBI.  ;D
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: FreeThinker on April 07, 2011, 06:36:27 am
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 ;D ;D ;D
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Mr J on April 08, 2011, 11:16:21 am
Check out my video response www.n1ir.com (http://www.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.
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: FreeThinker on April 08, 2011, 07:58:50 pm
Reveal has been posted. Nice one!
Title: Re: EEVblog#160 – 555 Timer Easter Egg?
Post by: Hero999 on April 09, 2011, 02:07:42 am
I get comments like that all the time!
They wouldn't now what enthusiasm is if it bit them on the arse.
Going by the comments, they also lack a sense of humour.