General > General Technical Chat

Where have you actually come across a 555 timer in the wild?

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T3sl4co1l:
For sure, there's no reason for a 555 as a timer... perhaps it was just being used as a schmitt trigger buffer/driver?

Tim

magetoo:
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.

Phaedrus:

--- Quote from: magetoo on April 01, 2014, 12:44:30 pm ---
--- Quote from: Phaedrus on April 01, 2014, 12:27:19 am ---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.

--- End quote ---

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?)

--- End quote ---

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.

G7PSK:
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.

thomastheo:

--- Quote from: mojo-chan on April 01, 2014, 03:30:20 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.

--- End quote ---

That's quite elegant, and reliable to boot.

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