Author Topic: Where have you actually come across a 555 timer in the wild?  (Read 32756 times)

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Offline T3sl4co1l

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #25 on: April 01, 2014, 12:58:20 pm »
For sure, there's no reason for a 555 as a timer... perhaps it was just being used as a schmitt trigger buffer/driver?

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Offline magetoo

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #26 on: April 01, 2014, 03:20:50 pm »
Maybe "debounce" wasn't exactly correct..  My guess is it was there to guarantee a minimum on time so that the CPU would have time to deal with the interrupt before the next could come in.
 

Offline Phaedrus

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #27 on: April 01, 2014, 04:01:38 pm »
They get used in cheap PC motherboards some times to drive the motherboard speaker. Other times they use a piezo, or on higher end boards they'll use a more advanced audio chip.

Are you sure?  I thought this function was integrated in the chipsets everyone use.  (Or is it considered "legacy hardware" nowadays and has been dropped?)

I haven't seen it in a while, so I guess it's deprecated. But I remember seeing it on an old Asus AMD board, socket 939. And I thought I've seen them on a few other motherboards as well.
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Offline G7PSK

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #28 on: April 01, 2014, 05:11:28 pm »
The first MIG welder I bought had two 555 chips, one to time the post flow and one for the wire feed motor burn back and stitch weld. I still have the circuit diagram somewhere.
 

Offline thomastheoTopic starter

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #29 on: April 01, 2014, 05:29:06 pm »
We designed a product with integrated battery charger for NiMH cells at work. Because the MCU is rather busy and the programmer didn't want to enable the watchdog (the code was mature, the battery charger was added towards the end of the project!) so to avoid the situation where the MCU was locked up and the battery charger still pumping current into the cells until they died we used a 555 on the charger enable line. The MCU has to pull it low at least once every 10 seconds or the charger turns off. The 555 is basically a watchdog for the charger.

That's quite elegant, and reliable to boot.
 

Offline mc

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #30 on: April 01, 2014, 06:00:40 pm »
In a 24 to 12volt dropper for trailer electrics on a lorry. Quite an over-engineered solution, but I'm guessing they just keep using an old design rather than redesign it.
 

Offline TheWelly888

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #31 on: April 01, 2014, 06:46:41 pm »
I've seen medical equipment that uses those 555 and 556s ICs for basic square wave generation.
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Offline fcb

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #32 on: April 01, 2014, 06:56:02 pm »
I designed one into a product last month.  It generates ~96KHz to bootstrap an isolated supply (until the system is booted and can generate precision 96KHz).
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Offline Kryoclasm

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #33 on: April 01, 2014, 07:19:56 pm »
Recently in a rooftop flashing beacon.
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Offline TVman

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #34 on: April 01, 2014, 07:40:31 pm »
 :-//
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Offline Neilm

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #35 on: April 01, 2014, 08:09:37 pm »
I had to make a small plug in device to allow the product I had designed to be run under computer control. I put a 555 in it to generate a square wave - see pin toggle real device present.
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Offline david77

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #36 on: April 01, 2014, 08:11:58 pm »
In my 20 EUR cheapie toaster, used as timer for the bread ejector thingie. With the obligatory knob on the side to choose how burnt you'd like your bread.

I've used it and will continue using it myself for all kinds of things, but you can hardly call what I do "production".
« Last Edit: April 01, 2014, 08:14:16 pm by david77 »
 

Offline steve30

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #37 on: April 01, 2014, 09:02:09 pm »
They are used in some 68000 based computers in the reset circuit (including the Amiga 500+). Can't remember exactly what it does though. We had an educational 68k board at college, and the documentation explained its purpose, but I forget.

They are quite old designs though. I very rarely see 555 chips in use in products. Or at least not ones that are marked with '555'.
 

Offline lapm

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #38 on: April 01, 2014, 09:17:42 pm »
Last time i run into one on wild was one of those orange road flashes. The 555 was running flashlight bulb throw transistor.. Transistor had died, so needed replacement.. Was beyond me why friend of mine wanted it fixed instead of buying new one...

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Offline magetoo

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #39 on: April 01, 2014, 10:02:11 pm »
Are you sure?  I thought this function was integrated in the chipsets everyone use.  (Or is it considered "legacy hardware" nowadays and has been dropped?)

I haven't seen it in a while, so I guess it's deprecated. But I remember seeing it on an old Asus AMD board, socket 939. And I thought I've seen them on a few other motherboards as well.

I meant the other way around, older machines will have something that is compatible to an actual 82xx (or whatever the number was) timer chip, not a 555, and probably needs that compatibility to be able to run DOS or something.

So I imagine slightly newer systems that don't need the compatibility could have dropped it and used something else for a beeper instead, like the 555 triggered by a GPIO.  (And anything recent would get rid of the internal speaker altogether.  Or use a "real" audio chip?)

Historic note: In the original PC, the timer chip had three separate timers - it generated a periodic interrupt at 18.2 Hz for DOS, drove the speaker with another timer, and also did a third thing I can't remember.
 

Offline T3sl4co1l

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #40 on: April 01, 2014, 10:37:03 pm »
Historic note: In the original PC, the timer chip had three separate timers - it generated a periodic interrupt at 18.2 Hz for DOS, drove the speaker with another timer, and also did a third thing I can't remember.

Third is actually the first (timer 0): interrupt for the DMA controller to perform another DRAM refresh.  Every couple of microseconds I think.

The 18.2Hz is used by the clock (at least when DOS is handling it, I think?).  You can hijack the interrupt and use the count for something else (say, an in-game timer to trigger another frame of activity), but don't be surprised if your system time is running slow afterwards. ;D

This, by the way, is precisely why, if a motherboard had a 555, it's not used to generate PC tones: the timer has a pin toggle mode which does it directly.  Give or take a driver for the PC speaker (2" 8 ohm in the old fashioned models, usually some piss tiny piezo these days).

All this stuff was integrated first into a SuperIO chip (along with all the other system functions, and serial and parallel), then into the South Bridge when that become a thing.  If your motherboard has a BIOS, it has all of this stuff in it somewhere; UEFI models may not, I don't know.

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Offline Jarrod Roberson

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #41 on: April 09, 2014, 07:18:49 pm »
Ben Heck finds a 555 timer chip in SOT packaging no less in a drill trigger assembly!

http://youtu.be/PUZyzU24Ta4?t=3m53s
 

Offline peter.mitchell

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #42 on: April 13, 2014, 04:43:19 am »
I've seen a few of them on power supplies for fan failure. The RPM line from the fan triggers it a minimum number of times a second.
 

Offline kolbep

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #43 on: April 13, 2014, 05:12:50 am »
Saw a 556 in a Barcode Scanner that they use at the Supermarket tills...
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Offline Anks

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #44 on: April 13, 2014, 05:16:08 pm »
I saw two just the other day in a Crown high power audio amplifier.  At a guess I'd say the amp design is from about 10-15 years ago.

Crown amplifiers that use the VZ supply (variable impedance) Macrotech 5000VZ and 3600VZ are the most popular. Its very clever in that its quickly switches voltage dependent on the needed output so the transistors don't have to dissipate the extra unneeded energy as heat.
 

Offline NiHaoMike

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #45 on: April 14, 2014, 03:07:19 am »
I saw two just the other day in a Crown high power audio amplifier.  At a guess I'd say the amp design is from about 10-15 years ago.

Crown amplifiers that use the VZ supply (variable impedance) Macrotech 5000VZ and 3600VZ are the most popular. Its very clever in that its quickly switches voltage dependent on the needed output so the transistors don't have to dissipate the extra unneeded energy as heat.
Some modern digital amplifiers also vary the supply voltage depending on the volume setting. Apart from the efficiency improvement, it makes it easier to get good resolution at low volume settings. Some others have multiple fixed voltage rails and are basically multi level inverters.
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Offline kolbep

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #46 on: April 14, 2014, 01:12:29 pm »
Took a lot of searching, but I just found one in the wild....








« Last Edit: April 14, 2014, 01:14:31 pm by kolbep »
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Offline madires

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #47 on: April 14, 2014, 01:30:19 pm »
Took a lot of searching, but I just found one in the wild....

I hope that wild electronics bug didn't bit you.  ;)
 

Offline kolbep

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #48 on: April 14, 2014, 01:54:11 pm »
Now just to track down a resistor colony, and I should be well on my way....
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Offline SeanB

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Re: Where have you actually come across a 555 timer in the wild?
« Reply #49 on: April 14, 2014, 06:14:58 pm »
Time to mow your lawn, all the rain is getting it growing nicely.
 


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