EEVblog #555 - 555 Timer Kit - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: December 10, 2013, 09:57:00 pm
content: Dave celebrates the classic 555 timer IC by building the Evil Mad Scientist "three fives" discrete timer kit.Some scope measurements and an explanation of the internal 555 timer circuitry follow.Construction:http://youtu.be/U6qZPx4uD0g?t=5m10sTesting:http://youtu.be/U6qZPx4uD0g?t=34m35sCircuit Description:http://youtu.be/U6qZPx4uD0g?t=38m16sWaveforms:http://youtu.be/U6qZPx4uD0g?t=54m35sClassic old Signetics 555 timer datasheet:http://serge.bertorello.free.fr/compsnts/ne555%20&%20ne556.pdfThe kit:http://shop.evilmadscientist.com/productsmenu/tinykitlist/652Han's Book on Analog chip design:http://www.designinganalogchips.com/

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 10, 2013, 10:03:06 pm
content: Ha, I forgot I wanted to buy one of these! Thanks for the reminder, just ordered one! $40 shipped.?

author: AG6QR
author_rank: Frequent Contributor
timestamp: December 10, 2013, 11:30:46 pm
content: Excellent choice for the 555th video! I've wanted to get one of these kits, too. Absolutely no practical reason for me to have it, but it's so cool.

author: Thor-Arne
author_rank: Unknown
timestamp: December 10, 2013, 11:44:14 pm
content: Nice kit.I find it relaxing to watch the soldering videos, but it's more relaxing to solder myself.On these videos a overlay with Dave's chattering face in the corner could IMO be an enhancement.

author: Schwuuuuup
author_rank: Newbie
timestamp: December 10, 2013, 11:54:44 pm
content: Yes watching Dave solder is meditative as well... maybe I Loop it and use it as a screensaver ;-)Also I learned so much about the 555 which I used before but didn't bother to understand it.Another great Video!By the way ... if a Name starts with SCH it's almost always German, and you pronounce it, like the C wasn't there... so my Nick name here should read shwooooop to you ;-)

author: c4757p
author_rank: Super Contributor
timestamp: December 11, 2013, 12:02:52 am
content: I'm torn between loving the black solder mask because it looks like a real chip, and hating it because invisible traces on a kit is kind of a rubbish idea IMO.Too bad they couldn't silkscreen the circuit diagram over it.

author: skycarl
author_rank: Newbie
timestamp: December 11, 2013, 01:09:35 am
content: Great idea for the 555th vid. Good teaching on the chip as well.

author: deth502
author_rank: Frequent Contributor
timestamp: December 11, 2013, 01:10:27 am
content: now we are going to have to wait until the 7555th episode to learn about CMOS

author: timelessbeing
author_rank: Frequent Contributor
timestamp: December 11, 2013, 01:14:32 am
content: What size is the soldering iron tip you used in the video?

author: nathanpc
author_rank: Unknown
timestamp: December 11, 2013, 01:34:18 am
content: Awesome special video. By the way, I think current mirrors would be a awesome subject for a Fundamentals Friday.

author: juanfermed
author_rank: Regular Contributor
timestamp: December 11, 2013, 02:28:28 am
content: Hi Dave, I join to Nathanpc: Fundamentals Friday on Current Mirrors. Great video on 555, thanks!

author: ashplant
author_rank: Newbie
timestamp: December 11, 2013, 03:11:01 am
content: Great video. And great subject.I first encountered the 555 when I built a random number generator, decades ago, epochs ago. It pulsed at a few MHz into a super-simple counter. The counter went "1, 2, 3... 14, 15, 1, 2, 3... ". But all you saw at the output was a blur, until you broke the connection between the timer and the counter. Then a number magically and randomly appeared.The best part was building it. For the sake of debugging, I initially used a 33 mF timing cap. This meant that the 555 pulsed a about a Hertz. I watched the counter count up and reset. When I broke the connection the counter stopped.Then I changed the value of a capacitor (something pF) and a deterministic system that did essentially nothing, became a random-like system that did magic.

author: Macbeth
author_rank: Super Contributor
timestamp: December 11, 2013, 03:22:57 am
content: Quote from: ashplant on December 11, 2013, 03:11:01 amSurely not? The upper frequency limit is in the 100kHz range, maybe 300kHz or so with the later ones?I am amazed that this IC (and the 741 op amp) are still classics and produced to this day!

author: Six_Shooter
author_rank: Regular Contributor
timestamp: December 11, 2013, 03:38:38 am
content: Quote from: deth502 on December 11, 2013, 01:10:27 amLOL!There is some looking forward to the 1455th video for the TTL compatible version.I kinda wonder if Dave got a second 555 timer kit to make a 556 chip for the 556th video. lol

author: free_electron
author_rank: Super Contributor
timestamp: December 11, 2013, 04:32:32 am
content: on to video 741 ...

author: bandgap
author_rank: Contributor
timestamp: December 11, 2013, 04:39:07 am
content: Excellent video! I really like the little "doh" screw ups. Reminds us that you're human (as we all are!)You convinced me to order a kit to use in my classes.-Clayton

author: Stonent
author_rank: Super Contributor
timestamp: December 11, 2013, 04:47:39 am
content: Quote from: ben_r_ on December 10, 2013, 10:03:06 pmI went the cheap route and spend about $2.00 on the transistors and resistors and ordered some tinned protoboard.

author: Stonent
author_rank: Super Contributor
timestamp: December 11, 2013, 04:49:11 am
content: Quote from: Six_Shooter on December 11, 2013, 03:38:38 amVideo 595 is not that far, he can talk about shift registers. Maybe make one from scratch?

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 11, 2013, 05:06:09 am
content: Quote from: Stonent on December 11, 2013, 04:47:39 amHa yea that is the cheap route! I already have all the parts laying around as it was and I could have a circuit board made custom for myself for less as well. However I didnt buy it to use it for anything other than a conversation piece on my desk at work. I think its really cool looking and the fact that its functional makes it even better!

author: Six_Shooter
author_rank: Regular Contributor
timestamp: December 11, 2013, 05:12:43 am
content: Quote from: free_electron on December 11, 2013, 04:32:32 amI was actually thinking of something similar and how we missed videos #339, #393 (and others) in that theme. lol

author: Stonent
author_rank: Super Contributor
timestamp: December 11, 2013, 05:29:30 am
content: Quote from: ben_r_ on December 11, 2013, 05:06:09 amI am somewhat hoping someone makes another board from the schematic and releases it.I noticed the terminal screws look almost exactly like VESA monitor mount thumb screws.

author: kaushleshchandel
author_rank: Newbie
timestamp: December 11, 2013, 07:28:03 am
content: I agree soldering is so relaxing... After a day of work, I go home and work on some projects; soldering. The soft metal melting, and that weak sizzling sound of flux is amazing..

author: Six_Shooter
author_rank: Regular Contributor
timestamp: December 11, 2013, 07:55:39 am
content: The more I work on my "robot" project that is due tomorrow using a Freescale Dragonfly board and Code Warrior, the more I am reminded that my favorite programming language is Solder. My Solder debugging tools show me errors that I can understand.

author: Goophy629
author_rank: Contributor
timestamp: December 11, 2013, 10:03:44 am
content: finally a tribally exiting assembly+soldering videodamn I watched it all through....Wondering if Dave has no fear of the leaded smoke...

author: EEVblog
author_rank: Unknown
timestamp: December 11, 2013, 10:09:34 am
content: Quote from: Goophy629 on December 11, 2013, 10:03:44 amThere is no lead in the smoke, that's the rosin flux.

author: Stonent
author_rank: Super Contributor
timestamp: December 11, 2013, 10:10:07 am
content: Quote from: Goophy629 on December 11, 2013, 10:03:44 amWhat's this leaded smoke you speak of?

author: BravoV
author_rank: Super Contributor
timestamp: December 11, 2013, 10:37:57 am
content: Quote from: EEVblog on December 11, 2013, 10:09:34 am+1Just fyi, although pure lead (Pb) melting point is at about 320 C, which is considered quite low and easily reached at solder tip, but the "boiling" point is at about 1700 C which is way too far for it to even turned into vapor/gas state.Even its mixed with other other metal like Tin which may lower those points, still it wont get near within solder tip's temperature range, unless your solder tip can get into +1000C range, then you can start to worry about that.

author: c4757p
author_rank: Super Contributor
timestamp: December 11, 2013, 11:23:36 am
content: The current mirror works by matching Vbe at one current in one transistor to Vbe at the same current in another transistor. A PN diode will not have the same threshold voltage. The two devices should ideally be identical (as in, not just both 2N3904, but both measured and matched from a bunch).

author: 84GKSIG
author_rank: Regular Contributor
timestamp: December 11, 2013, 11:34:11 am
content: As the 555 is an important device in electronics I feel it would appropriate to say happy 555th official video blog videokeep them coming Davedidnt mind the assembly videoI love the 555 and I must say, if that little chip didnt exist right now, sure they would of been other ways to get the job done no doubt but it opened up a whole new world in electronics I feel and I still enjoy messing with them and a I do agree, there a great place to start for any one with an interest in electronics.

author: TheWelly888
author_rank: Frequent Contributor
timestamp: December 11, 2013, 11:47:53 am
content: Damn! I was hoping that the 555 board would not work first time!Still, perfect perfect for the 555th video!As to lead solder vapourising - of course it doesn't, but Health & Safety told my pregnant colleague to leave the workshop when one of us needed to do some soldering on the workshop's soldering station! I remember asking if it was to do with the flux fumes but I was told that it was to do with the lead vapour!!!Think I'll get myself a kit too!Edited post to add:Went as far as the Checkout and entered my address etc - cheapest shipping to UK is $42 - No way Jose!!

author: Six_Shooter
author_rank: Regular Contributor
timestamp: December 11, 2013, 12:13:51 pm
content: If I didn't already have dozens of 555s and 1455s kicking around, I'd grab one of these kits, but it would really just end up be a wall hanging.

author: Frost
author_rank: Regular Contributor
timestamp: December 11, 2013, 01:17:16 pm
content: Quote from: TheWelly888 on December 11, 2013, 11:47:53 amSame here in Germany, the shipping costs more than the kit itself.But I but i think if I should send a mail to them and ask if theyplan to add these kit to their Web store.Watterrott sells parts from Evil Mad Scientist and ship within Europe.

author: Gath
author_rank: Contributor
timestamp: December 11, 2013, 01:31:37 pm
content: I liked the video! Nice tribute to the famous triple five ^^After this, I feel like it would be really cool to have a fundamental Friday on BJT (or a couple)Quote from: TheWelly888 on December 11, 2013, 11:47:53 am+1 Where is Murphy when you need him ?

author: zapta
author_rank: Super Contributor
timestamp: December 11, 2013, 05:13:19 pm
content: Watched the first video and loved it. Will watch the rest later today. I learned for example about the layering by height approach. I also noticed that Dave is using a large tip solder iron (much larger than the pads) and don't clean up the tip that often. More than one way to skin a cat...Dave, if you run out of words while soldering, a joke or two would do. Just not that 'An Australian, an American and a French walk into the bar...' one.

author: trackman44
author_rank: Regular Contributor
timestamp: December 11, 2013, 05:49:08 pm
content: I loved the video. It means anybody could build the circuit themselves, or build parts of the circuit for their own projects, with common parts that are easily accessible. Great job Dave.I didn't find the video boring at all, quite relaxing though. Keep them coming!Will

author: opablo
author_rank: Regular Contributor
timestamp: December 11, 2013, 06:02:48 pm
content: Quote

author: Jon86
author_rank: Frequent Contributor
timestamp: December 11, 2013, 06:26:30 pm
content: Anyone notice the the unintended pun? Lead free solder, it's not worth the HASL.

author: Frantone
author_rank: Regular Contributor
timestamp: December 11, 2013, 06:38:21 pm
content: A discrete kit was on my list of PCB projects - but this kit looks like fun and I really like the legs! I will have to check out what else they make. Looks like you had fun too Dave!

author: opablo
author_rank: Regular Contributor
timestamp: December 11, 2013, 07:05:22 pm
content: fyi... I'm planning on doing this as my next woodworking project...anyone interested in sharing the project ? (sharing plans, meassurements, materials, paintjob ideas, etc)the size of the one on this pictures look ok for my couch...

author: firehopper
author_rank: Frequent Contributor
timestamp: December 11, 2013, 08:14:10 pm
content: Quote from: opablo on December 11, 2013, 07:05:22 pmmake it functional too

author: eV1Te
author_rank: Regular Contributor
timestamp: December 11, 2013, 09:43:00 pm
content: Great idea with the 555 kit! You really hit the nail on the head this timeBy the way, the lead in the solder does actually vaporize when you are soldering, but it is not visible and the flux is more toxic (since you have much higher concentration of the flux vapors), the lead concentration in the air at soldering temperatures is around or below 1 ppm.

author: Frantone
author_rank: Regular Contributor
timestamp: December 11, 2013, 10:02:18 pm
content: Quote from: eV1Te on December 11, 2013, 09:43:00 pmThere is a little bit of lead in everything - a little won't hurt you. But lead boils at over 3000°F so I am pretty sure lead does not vaporize at all at 650-700°F at sea level, even in an alloy. Any contamination you get is certainly going to be from handling the solder with your bare hands rather than flux fumes. I knew a guy once who ended up detoxing in the hospital because he was holding the solder wire in his mouth to free up his hands while working..

author: electronics man
author_rank: Frequent Contributor
timestamp: December 11, 2013, 10:14:03 pm
content: that isnt cheep, plees Dave could you do stuff which is more open to the average amature hobbiest whith no income who thinks twice before spending £20

author: JOERGG
author_rank: Contributor
timestamp: December 12, 2013, 12:58:10 am
content: I am only familiar with analog scopes so far where you on a fast signal does not see the vertikal part of the line. In this video i noticed that the vertikal part of the square wave on channel 3 is drawn higher than the signal temporary. Can somebody explain this for me please. Is this so on all digital scopes?

author: Excavatoree
author_rank: Frequent Contributor
timestamp: December 12, 2013, 01:48:39 am
content: Dave's transistor outline story brought back a memory. I hadn't been working as a repair tech for long when I had the dreaded amplifier on the bench. I was doing some checks, when it began to make a horrible noise. The boss yelled at me to cut the power, but I got fumble fingered and couldn't do it in time - there were flames.I cleaned the (not badly damaged) board, checked all the transistors and replaced the bad ones. I checked everything I could, but the thing wouldn't work. It was a direct coupled amp, and I had an offset voltage on the speaker outputs. Finally, the boss had to look at it, and I had put a transistor in according to the silk screen, and not as it should have been. I learned that lesson the hard way. That's all it was, I had indeed found all the bad parts - it was my poor re-installation.

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 12, 2013, 03:09:02 am
content: Quote from: Stonent on December 11, 2013, 05:29:30 amAnd if someone were to remake another 555 discrete component board like this ideally cheaper, what would you imagine it having on it, featuring or looking like exactly?

author: Stonent
author_rank: Super Contributor
timestamp: December 12, 2013, 03:35:22 am
content: Quote from: ben_r_ on December 12, 2013, 03:09:02 amMore or less a similar board, minus threaded holes, foam legs or parts.Basically I really like this, but I can't justify $35 for it. If someone were to offer a functional equivalent bare board that I could use my own components, thumb screws and legs for under $10 I'd most likely buy it.

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 12, 2013, 03:37:15 am
content: Quote from: Stonent on December 12, 2013, 03:35:22 amGotcha. Be kinda nice to have a few extra holes for pin headers at some key places to use as test points as Dave mentioned in his video right after he completed it. Obviously have to decide on those going into the design though.

author: Six_Shooter
author_rank: Regular Contributor
timestamp: December 12, 2013, 03:54:35 am
content: Quote from: Stonent on December 12, 2013, 03:35:22 amAt that point I'd just use a bona fide 555.The only reason to buy this kit is because of the novelty. To have it look like an overgrown IC, and to use discrete parts to make it functional, is what makes it interesting to some of us nerds. It's not bought because it's economical or has any real use.

author: Stonent
author_rank: Super Contributor
timestamp: December 12, 2013, 04:02:15 am
content: Quote from: Six_Shooter on December 12, 2013, 03:54:35 amOh I would plan on recreating the IC look.Perhaps offer more than one way to attach wire. Or have the spots drilled and tinned ready to go for other methods.

author: Frenchie
author_rank: Regular Contributor
timestamp: December 12, 2013, 05:32:58 am
content: Quote from: Frantone on December 11, 2013, 10:02:18 pmPurely semantics but it will do, but the amount will be so small it's never going to be a problem (or even measureable for that matter).

author: Stonent
author_rank: Super Contributor
timestamp: December 12, 2013, 06:46:28 am
content: Quote from: electronics man on December 11, 2013, 10:14:03 pmWell there's your problem!I have an income but most of my money is gone shortly after it comes in, after all my bills are paid I then do my best to make sure other family members are able to pay their bills. My mom's car just broke a connecting rod and I had to use my Christmas bonus towards getting her another car. So right now I try to keep about $20 or $40 a month for my hobby and beer.

author: Bored@Work
author_rank: Super Contributor
timestamp: December 12, 2013, 07:17:30 am
content: If you need to watch therapeutic videos, have a look at Bob Ross' "The Joy of Painting" TV series.We don't make mistakes, we make happy little accidents.

author: G7PSK
author_rank: Super Contributor
timestamp: December 12, 2013, 08:53:47 am
content: Quote from: eV1Te on December 11, 2013, 09:43:00 pmThere would be no lead vapor at soldering temperature but there could well be a minute amount of lead aerosol caused by the flux boiling and ejecting some lead as it dose so. But even so it would normally be at such a low level that it would be of no health concern.

author: Stonent
author_rank: Super Contributor
timestamp: December 12, 2013, 09:34:05 am
content: Quote from: Bored@Work on December 12, 2013, 07:17:30 amFor anyone outside the US:

author: miceuz
author_rank: Frequent Contributor
timestamp: December 12, 2013, 11:56:58 am
content: Dave, I agree, the soldering part of the video was somewhat boring. An ok background for I was soldering some stuff too while watching, but not much content. But I would guess this is due to monotonic nature of the particular kit - what do you have - just resistors and transistors in same packages for a fixed design ages old - not much to comment on really.I'd suggest you to try it once on another kit - the one that has more diversity in it - you'd have more to comment on and in my opinion it could make a great video. Say, the video about microscope ring light soldering - that was essentially a "putting a kit together" video and that one was not boring a single bit.

author: amyk
author_rank: Super Contributor
timestamp: December 12, 2013, 01:01:01 pm
content: Not sure if this is a coincidence but here is a die photo of a CMOS version:http://www.bunniestudios.com/blog/?p=3542

author: EEVblog
author_rank: Unknown
timestamp: December 12, 2013, 01:31:59 pm
content: Quote from: ben_r_ on December 12, 2013, 03:09:02 amWell whilst I liked the look of the board and thumb screws, practical wise it's just a PITA to wire up.For practical use, I'd have one that plugs into an existing breadboard somehow.

author: jancumps
author_rank: Unknown
timestamp: December 12, 2013, 02:18:46 pm
content: Maybe the market is ready for a gigantic breadboard

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 12, 2013, 03:40:52 pm
content: Quote from: Six_Shooter on December 12, 2013, 03:54:35 amI bought it for the same reason as well. However, if a design can be redone for a different or better reason, thats a whole different thing and reason to buy.

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 12, 2013, 03:43:14 pm
content: Quote from: EEVblog on December 12, 2013, 01:31:59 pmGood idea. Have to condense down the board quite a bit to fit it on a standard sized hobby breadboard, but it could probably be done.Anybody have a good, detailed schematic of the 555 schematic like the one Dave used in the last part of his video? Or Dave could you post that one you printed out?

author: Rodville
author_rank: Contributor
timestamp: December 12, 2013, 05:39:47 pm
content: Great video. I would like to see more videos of you soldering kits with the "pointless rambling". It is very interesting to hear some of your random thought as you are building a board. Believe it or not it is relaxing to watch, and watching you solder had helped my technique immensely.

author: Stonent
author_rank: Super Contributor
timestamp: December 12, 2013, 06:41:35 pm
content: Quote from: ben_r_ on December 12, 2013, 03:43:14 pmSomeone posted it in the other 555 thread

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 12, 2013, 06:52:03 pm
content: Quote from: Stonent on December 12, 2013, 06:41:35 pmHavent seen any other 555 threads, but Ill take a look.

author: Ronald1962
author_rank: Contributor
timestamp: December 13, 2013, 08:27:35 pm
content: It's a nice idea.I just wanted to order one, but...This thing cost 35 US $.Not cheap but o.k.The cheapest shipping rate to Germany is another 35 US $And that is redicculous!So no kit...Great video!

author: Slothie
author_rank: Regular Contributor
timestamp: December 13, 2013, 10:11:14 pm
content: Quote from: G7PSK on December 12, 2013, 08:53:47 amWrong!Boiling point is just the point that the vapour pressure in the liquid reached ambient. Water boils at 100 degC but will happily evaporate at much lower temperatures. Likewise liquid lead will evaporate at much lower temperatures than it boils at.However, the amount of lead evaporating during soldering will be tiny and of no concern. Youre in more danger from holding the solder. The fumes are bad because of the smoke contains complex chemicals which are corrosive (after all, thats its job!) and possibly carcinogenic. But blowing gently as you solder is all the effort needed to prevent inhaling it, unless your doing a marathon session in a small room, in which case fume extraction is a good idea, as it is if you do it all day every day.

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 14, 2013, 01:39:38 am
content: Just got mine built. They are local in my state so shipping was very fast. Took me about a half hour. Awesome little kit, but yes a bit pricey. Oh well, itll make a great conversation piece for my desk at work and thats what I wanted it for.

author: Bored@Work
author_rank: Super Contributor
timestamp: December 14, 2013, 06:08:36 am
content: Quote from: Slothie on December 13, 2013, 10:11:14 pmThe serious measurements (measurements, not theoretical speculations), could not detect any lead, using the most sensitive detection methods. That's good enough for me and I don't care if some made-up theory says there could be some lead vapor.

author: SArepairman
author_rank: Frequent Contributor
timestamp: December 14, 2013, 07:16:06 am
content: I think that kit is trash! I absolutely LOATHE the black solder mask on this board, a demonstration board should have the traces shown, so you can get an idea of how the parts are wired, this is WAY too interesting of a detail to miss, its like a picture of a strip tease vs a dildo video.I just cannot forgive this board. It looks like satan made it.The wiring is ultra important to me in the case of a 555. A god damn block diagram tells you more then a glance at that board.

author: EEVblog
author_rank: Unknown
timestamp: December 14, 2013, 08:25:42 am
content: Quote from: ben_r_ on December 12, 2013, 03:43:14 pmIt's on the EMSL web site.A board using SMD parts and test pads would probably allow a size that plugs into a breadboard.

author: DL8RI
author_rank: Regular Contributor
timestamp: December 14, 2013, 10:39:27 am
content: Hi,QuoteWhy so heated up?It is made to look like a Chip. Therefore black color is essential.I think it looks nice, and the stuff isn't that complicated... the schematics are sufficient.If you want such a thing as "training", build it on a breadbord or free-flying-solder w. GND-Plane. The kit is a nice geek-gimmick, but otherwise quite useless

author: Stonent
author_rank: Super Contributor
timestamp: December 14, 2013, 10:45:09 am
content: Quote from: ben_r_ on December 12, 2013, 03:43:14 pmHere ya go!http://shop.emscdn.com/catalog/emskits/555/kit/555_datasheet_RevA3.pdf

author: SeanB
author_rank: Super Contributor
timestamp: December 14, 2013, 11:39:18 am
content: BTW the writing Dave was muttering about on the PCB is the Underwriters Association registration number, issued to the manufacturer as a certification of conformity to a standard. Nice having that on a kit.Myself i like the kit idea, a nice thing to see there, with a modicum of care and thought put into the layout and design.Must look at getting the die photo of the 555 printed on a canvas sheet and frame it.

author: Phroon
author_rank: Contributor
timestamp: December 14, 2013, 10:19:46 pm
content: Quote from: EEVblog on December 12, 2013, 01:31:59 pmSomething like this?http://www.evilmadscientist.com/2013/555-ice/

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 15, 2013, 12:59:00 am
content: Quote from: Phroon on December 14, 2013, 10:19:46 pmHa ha Wow! Yea thats one way to do it! There are also the little pads with holes next to each of the thumb screws along the edge of the board that Im sure either pin headers or at least wire leads could be soldered to for tapping into the legs.

author: VK3DRB
author_rank: Super Contributor
timestamp: December 15, 2013, 01:52:21 am
content: Thanks for the EEVBLOG! The kit could be made mandatory in all high schools. Sure beats reading Shakespeare. You never know we might even become a "knowledge nation" one day.A few comments if I may...THE SIDE CUTTERS:The side cutters look pretty average. I hate having to use crappy side cutters. Every place I have worked at I have reached out to unbelievers and witnessed born again conversion to the TRONEX brand of side cutters. These are a godsend to electronics engineers, technicians and hobbyists. They are of vastly superior quality. They seem to last forever providing you don't cut nails with them. (They do work well on fingernails though!). Mektronics sells a variety of these side cutters, sometimes on special. My favourite is the Tronex 7111 side cutters for general PCB work. If I recall they sell for around $60 or so but will last a lifetime. And no, I don't work for Mektronics.BLACK PCBs:Black PCB's look sexy and might even attract chicks. I recently followed one of Dave's EEVBLOG suggestions with a company in NZ called Circuit Labs and got a 4 layered complex board done in matt black. Like with Dave's experience the quality was outstanding, the price cheap and the turnaround time very quick. The reason I got black was the board was used in an optics application and light reflection has to be minimised. Thanks for the tip Dave! I also found it to be very hard to trace PCB tracks visually, but they do look sexy.The 555:As for the 555, about 25 years ago some of the bipolar 555's from one manufacturer (not CMOS) were quite noisy. I suspected this was because the the totem pole output transistors could both turn on at the same time creating a very brief short from rail to ground. They were also not very reliable. Since then, if I have used these devices I use the CMOS variety.Finally, other ubiquitous nostalgic parts besides the '555 include the BC547, LM317, 7805. And let's not forget the 2N3055 and his best mate the MJE2955.cheers,another Dave.

author: notsob
author_rank: Frequent Contributor
timestamp: December 15, 2013, 02:54:20 am
content: If you read page 11-5 of 'designing analogue chips' by Hans Camenzind- he mentions this limitation in his original 555 design, and goes on to show how he would have designed it later in his life [ new design has approx twice the transistors in it ]Cheers

author: mrkev
author_rank: Regular Contributor
timestamp: December 15, 2013, 07:08:37 pm
content: I would like to see some measurments on those differential amplifiers and current mirrors.There is a reason why you won't see those very often in descrete designs, matched pairs on chip can be very precise, but when using descete parts, the VA char. and h21efor each transistor (especially in quad) can be really off.

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 15, 2013, 07:25:35 pm
content: Quote from: mrkev on December 15, 2013, 07:08:37 pmLOL its a fancy soldering kit man, not a precision replica...

author: Stonent
author_rank: Super Contributor
timestamp: December 15, 2013, 10:08:22 pm
content: I suppose you could check the HFE on each transistor with a transistor checker and try to match them that way.

author: mrkev
author_rank: Regular Contributor
timestamp: December 15, 2013, 10:51:47 pm
content: Quote from: Stonent on December 15, 2013, 10:08:22 pmWell It's more about the shape of V-A characteristic than h21e. But I was just curious what can you get from discrete solution...

author: SArepairman
author_rank: Frequent Contributor
timestamp: December 16, 2013, 11:42:20 pm
content: I think the trace wiring is beautiful, just looking at some wiring inspires curiosity. I got heated because I saw something that was one solder mask away from being beautiful, its like frustrating you know. It's like you built an awesome dinosaur skeleton and then you decided to throw a garbage bag over it, with the interests of teaching anatomy!!!!!!!!I could probobly tell you how a 555 timer works, but I know that if I wanted this "geek prop", especially to show others, it would be much cooler to have wiring.Even if someone does not know alot about electronics you can tell them "oh you see this little thing here with this wire going to it? well yea, that thing is pretty much just like a like this, when it sees something here then it lets electricity through here and...."I just don't see why it was done.Its just so much better to see the actual wiring then look at a schematic. It feels so much more real to see that little electrical connection then to look at a boring ass black and white document and believe that it is there.I don't think things should be made into black boxes unless they absolutely have to be.Quote from: DL8RI on December 14, 2013, 10:39:27 am

author: c4757p
author_rank: Super Contributor
timestamp: December 16, 2013, 11:57:48 pm
content: Quote from: SArepairman on December 14, 2013, 07:16:06 amYes, I know that when I see a picture of a strip tease, my first thought is "this would beinterestingif I could just see the goddamndildo!"

author: Six_Shooter
author_rank: Regular Contributor
timestamp: December 17, 2013, 05:17:15 am
content: I think you guys are making too big of a deal over the colour of solder mask.I like the black, I also like other colours of solder mask. I think a different colour would have been the wrong choice for this kit, simply due to how the finished product was to look. Whens the last time you saw a green or red 555 timer?

author: mrkev
author_rank: Regular Contributor
timestamp: December 17, 2013, 07:20:06 pm
content: Quote from: Six_Shooter on December 17, 2013, 05:17:15 amI don't like any solder mask, wanna keep all my PCBs unmasked

author: Stonent
author_rank: Super Contributor
timestamp: December 17, 2013, 07:27:45 pm
content: Quote from: mrkev on December 17, 2013, 07:20:06 pmHow about making the "foot stool" but have a lid on it that you can flip open to probe it?

author: ben_r_
author_rank: Frequent Contributor
timestamp: December 17, 2013, 08:43:36 pm
content: I think it looks awesome just the way it is! The flat black soldermask is mean to look like the flat black housing that the real 555 chips come in I think. Either way for what I bought it for, its perfect right on my desk

author: SArepairman
author_rank: Frequent Contributor
timestamp: December 18, 2013, 12:03:40 am
content: Quote from: Stonent on December 17, 2013, 07:27:45 pmI agree, it should have a black case that looks like the real chip and open up so you can look at the wiring under the hood, preferably with a single sided PCB using jumper wires if necessary.

author: c4757p
author_rank: Super Contributor
timestamp: December 18, 2013, 12:23:12 am
content: Quote from: SArepairman on December 18, 2013, 12:03:40 amWhy?

author: Stonent
author_rank: Super Contributor
timestamp: December 18, 2013, 11:45:30 am
content: And just because... I'd make the legs out of real metal and be live.

author: SArepairman
author_rank: Frequent Contributor
timestamp: December 19, 2013, 06:38:10 pm
content: Quote from: c4757p on December 18, 2013, 12:23:12 amso you can see exactly how everything is wired.ok maybe a ground plane is ok.

author: J4e8a16n
author_rank: Regular Contributor
timestamp: May 20, 2017, 06:50:20 pm
content: Here are some 555 LTSPICE files I created.

author: Roberts_Curiosity
author_rank: Contributor
timestamp: November 30, 2020, 01:05:14 am
content: I did this on breadboard and transistors:, easy, fun and educational.