How is sequential firing in electronics achieved?

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Discussion Overview

The discussion revolves around the mechanisms and technologies used to achieve sequential firing in electronics, particularly in applications such as lighting, maglev trains, and CCD arrays in cameras. Participants explore various electronic components and systems that facilitate this functionality, including timers, counters, multiplexers, and different types of switches.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants inquire about the methods used to turn on and off light bulbs and electromagnets in sequence, as well as the operation of CCD arrays in cameras.
  • One participant suggests using a timer or clock pulse generated by an NE555 chip, which feeds into a counter chip that increments in binary, allowing for specific output signals via digital gates.
  • Another participant mentions the use of jump counters within IC chips to switch electrical outputs, questioning the underlying electrical phenomena that enable this functionality.
  • A participant introduces multiplexers as a class of chips that can operate at high frequencies, comparing them to older mechanical systems like revolving contacts.
  • There is a discussion about whether IC chips drive electromechanical relays or use transistors for solid-state designs, indicating a dependency on the application.
  • Some participants recommend researching various power switches such as SCR, TRIAC, and MOSFET, noting their relevance to the topic.
  • One participant emphasizes the importance of understanding clock circuits and state machines as foundational knowledge in digital logic.
  • There is a reiteration of the need to understand the solid-state operation of IC chips compared to electromechanical contactors.

Areas of Agreement / Disagreement

Participants express various viewpoints on the technologies and methods used for sequential firing, with no clear consensus on a single approach or solution. Multiple competing views remain regarding the specific components and designs suitable for different applications.

Contextual Notes

Some discussions touch on the limitations of mechanical systems in terms of frequency and the need for solid-state solutions, but these aspects remain unresolved and depend on specific applications.

Bararontok
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How are light bulbs turned on and off in sequence for some signs and flat screen televisions?

How are electromagnets turned on and off in sequence to accelerate maglev trains and coil gun bullets?

How are the CCD arrays in electronic cameras turned on and off in sequence to transmit the captured images to the recording device through a serially transmitted electrical signal?
 
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For simple systems, a timer/clock pulse is generated (eg by an NE555 chip) then fed into a counter chip which will count up in binary (so for each pulse the counter will increment in binary - 0000, 0001, 0010, 0011, 0100 etc). Those binary states can then be combined via digital gates (AND/OR/NOT) to give output signals/states at specific time.

Fancier systems like washing machines use microcontrollers

In the olden days, it was reels with revolving contacts/bumps pressing microswitches.
 
Yes, usually the counter will be implemented as a jump counter so that the electrical output can automatically be switched from one output terminal on the IC chip to another output terminal but how is this accomplished electronically within the circuitry of the IC chip? What type of electrical phenomenon makes this possible?
 
There is a class of chip between microprocessor and just a bunch of gates called a multiplexer. A good example is the 8 line to 1 line 74151 IC.
These can operate at video frequencies and above.

These are electronic versions of the revolving contacts called actuators or contactors, which were actually pretty sophisticated and reliable so don't sneeze at them either. However mechanical systems are frequency limited to a few kHz at best.
 
Yes, how does the IC chip perform the function of the electromechanical contactor but in a solid state manner?
 
Depends on the application. In some cases the IC would drive electromechanical relays in other cases a transistor can be used to stick with a strictly solid state design.
 
Have you googled the spec sheet or multiplexer in general?

The following is a mid 70s circuit to put 8 channels on a single channel scope.
 

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You're looking for power switches. Look up SCR, TRIAC, ignitron, MOSFET, BJT, IGBT. There are others.
 
you should also look up how a simple clock or "multivibrator" works. you can actually build a simple one with an op-amp (wired up as a Schmidt trigger), a couple of resistors and a capacitor. the timing of the period has something to do with the RC time constant.

once you have a clock, the rest is all logic, then you need to learn how a flip-flop works. and then a "state machine". this is what you learn in your first digital logic course. you need to learn about AND, OR, and NOT gates, about truth tables, about Boolean algebra, and then about sequential state machines in general. that is when you'll first run into the concept of "microcode".
 
  • #10
You're looking for power switches. Look up SCR, TRIAC, ignitron, MOSFET, BJT, IGBT. There are others.

Not really these are just signal level power requirements.
 
  • #11
Studiot said:
Not really these are just signal level power requirements.

Maybe you missed this one:
Bararontok said:
Yes, how does the IC chip perform the function of the electromechanical contactor but in a solid state manner?
 

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