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I'm currently working on a project for an internship where I need to reverse engineer a design for a vibration simulator, which use two 556 timers in order to generate four output signals. The final prototype will be a PCB, and using 556 timers would be more expensive to produce.

My question: Are there any distinct differences between using two 556 timers vs. four 555 timers?

From looking at datasheets (NE556DR and NE555DR), the typical current draw from both seems to be the same. In this case, what are the advantages to using the 556 in this scenario?

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    \$\begingroup\$ not really, that's the point of the 556, it's just 2x 555 on one chip \$\endgroup\$
    – Criticizing Israel not allowed
    Commented Jul 27, 2023 at 18:12
  • \$\begingroup\$ @user253751: as short as that is, it's the answer -- you should go ahead and answer with it. \$\endgroup\$
    – TimWescott
    Commented Jul 27, 2023 at 18:14
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    \$\begingroup\$ @TimWescott I'm not confident about it and a 555/556 expert should make it an answer. \$\endgroup\$
    – Criticizing Israel not allowed
    Commented Jul 27, 2023 at 18:16
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    \$\begingroup\$ Just FYI, a single microcontroller with whatever it requires around it to work might be cheaper than those 555 chips and what they require around them to work. \$\endgroup\$
    – Justme
    Commented Jul 27, 2023 at 18:29
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    \$\begingroup\$ [Microcontroller] might, but then you need a programmer and skill in using it - not everybody is ready to take that plunge. \$\endgroup\$
    – rdtsc
    Commented Jul 27, 2023 at 19:13

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Using 4x555 instead of 2x556 is not a problem.

But there’s no single “555”. There are at least three variants (NE555, TLC555, TLV555) available just from TI, and other vendors have more. Same goes for 556. So you have to be very careful to do price research on all those parts, instead of looking between NE556 vs NE555. Price relations change as you go away from the original bipolar version to CMOS.

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    \$\begingroup\$ There's also differences in functionality between the bipolar (NE and SE versions) and CMOS versions. They usually work pretty much the same for the basic datasheet circuits, but if you start going "off label" then differences in function can become apparent in your circuit. \$\endgroup\$
    – TimWescott
    Commented Jul 27, 2023 at 20:50

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