Schematics Reading

  • Thread starter nDever
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  • #1
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Main Question or Discussion Point

Hey Guys,

I have built circuits based on schematics before but this diagram, as it stands, is confusing. The IC is the 8284 Clock Signal Generator and I know the chip has a Vcc pin but according to the diagram, power is not connected to the Vcc pin but directly to ground. In fact that pin is not even displayed. Don't ICs require power to function? I must reading this diagram incorrectly.

clock_circuit.png
 

Answers and Replies

  • #2
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Often if diagrams were to show all the connections, the schematic becomes confusing because of all the connections so the obvious connections are omitted. That's the case in this one but that doesn't mean the pins not shown aren't connected.

In this diagram Vcc is not directed to ground but through R1 and C1 to ground. Pin 11 is the reset pin. To reset the chip, S1 is closed and then opened. C1 charges through R1 and when it reaches a preset voltage the chip resets.
 
  • #3
davenn
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hi nDever,

agree with skeptic2's comments, sometimes reading schematics takes a little background knowledge/experience and some things are assumed to be known by
other users. that 10k resistor from VCC to pin 11 RES holds the reset pin HI till the
reset switch is pushed and held, allowing the pin 11 to go to GND once the capacitor
has discharged

here's a more accurate way of showing power connections to your cct as they has also omitted the GND connection to the chip
 

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