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means that a point in a circuit (a node) allows a relatively small amount of current through, per unit of applied voltage at that point. High impedance circuits are low current and potentially high voltage, whereas low impedance circuits are the opposite (low voltage and potentially high current).
167:. Since the terms low and high depend on context to some extent, it is possible in principle for some high impedance nodes to be described as low impedance in one context, and high impedance in another; so the node (perhaps a signal source or amplifier input) has
255:) output is not being driven to any defined logic level by the output circuit. The signal is neither driven to a logical high nor low level; this third condition leads to the description "tri-stated". Such a signal can be seen as an
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259:(or "floating" wire) because connecting it to a low impedance circuit will not affect that circuit; it will instead itself be pulled to the same
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voltages and are more prone to capacitive and inductive noise pick up. When testing, they are often difficult to probe as the impedance of an
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The high-impedance state of a given node in a circuit cannot be verified by a voltage measurement alone. A
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are actually tri-state capable outputs which have been internally connected to inputs (resulting in
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a high impedance node is one that does not have any low impedance paths to any other nodes
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or voltage on the node. High impedance signal outputs are characteristic of some
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as the actively driven output. The combined input/output pins found on many
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can match a high-impedance input source to a low impedance amplifier.
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High impedance inputs are preferred on measuring instruments such as
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Numerical definitions of "high impedance" vary by application.
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151:or other devices with high internal impedance.
210:more easily supply high-impedance inputs than
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115:Learn how and when to remove this message
165:in the frequency range being considered
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53:adding citations to reliable sources
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313:"What's a Tri-state Buffer?"
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21:Electrical impedance
229:Digital electronics
149:crystal microphones
292:pull-down resistor
155:Analog electronics
273:four-valued logic
269:three-state logic
235:Three-state logic
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321:. Retrieved
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105:January 2021
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47:Please help
42:verification
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204:Vacuum tube
192:transducers
129:electronics
323:2017-03-22
298:References
249:tri-stated
184:multimeter
141:voltmeters
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19:See also:
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200:amplifier
194:(such as
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