How is sequential firing in electronics achieved?

  • Thread starter Bararontok
  • Start date
  • #1
297
0

Main Question or Discussion Point

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?
 

Answers and Replies

  • #2
11
0
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.
 
  • #3
297
0
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?
 
  • #4
5,439
7
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.
 
  • #5
297
0
Yes, how does the IC chip perform the function of the electromechanical contactor but in a solid state manner?
 
  • #6
235
2
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.
 
  • #7
5,439
7
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.
 

Attachments

Last edited:
  • #8
1,679
3
You're looking for power switches. Look up SCR, TRIAC, ignitron, MOSFET, BJT, IGBT. There are others.
 
  • #9
rbj
2,226
7
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
5,439
7
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
1,679
3
Not really these are just signal level power requirements.
Maybe you missed this one:
Yes, how does the IC chip perform the function of the electromechanical contactor but in a solid state manner?
 

Related Threads for: How is sequential firing in electronics achieved?

  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
7
Views
7K
  • Last Post
Replies
1
Views
7K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
2
Views
1K
Replies
1
Views
891
Replies
6
Views
1K
Top