Linear power supply - Revision history

Jnc: +cat

2018-12-14T18:44:42Z

+cat

Jnc: Be explicit about the implication

2018-09-28T13:29:15Z

Be explicit about the implication

Jnc: Refer to VI conversion article

2018-09-28T00:32:33Z

Refer to VI conversion article

Jnc: typos

2018-09-23T18:59:59Z

typos

Jnc: Mention common input/output voltage relationship

2018-09-23T18:26:48Z

Mention common input/output voltage relationship

Jnc: An OK start

2018-09-23T17:51:26Z

An OK start

New page

A '''linear''' power supply is one that uses purely [[analog]] techniques (i.e. internal [[signal]]s with [[voltage]]s with continuously varying values) to convert input power to output, at the correct voltage needed. (Devices operating in this mode are said to be operating in their 'linear' mode.)

Linear supplies are generally inefficient since if they take in a given [[current]] (at the supply voltage), then without using a [[transformer]] (which only works with [[alternating current]]), there is no easy way to produce more than that much output current (since the number of [[electron]]s in the current is fixed, and 'electrons out' must equal 'electrons in').

Generally, the extra power (the actual amount is given by the [[ampere|amperage]] multiplied by the voltage drop from the input to the output) is discarded as heat.

The usual internal [[circuit]]ry is that a combination of a [[transistor]] and the load (output) are used as a voltage divider network; the [[emitter]] of the transistor is connected to the output, and the [[collector]] to the input voltage. The current through the transistor's [[base]] is adjusted so that the voltage drop across the load is as desired; the rest will be dissipated in the transistor.

Due to their low efficiency, in high-power applications they have generally been replaced by [[switching power supply|switching power supplies]].

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 Linear supplies are generally inefficient because of the [[VI conversion]] issue; since linear supplies are usually quite simple internally, they usually do not have any mechanism for this. Generally, the extra power (the actual amount is given by the [[ampere|amperage]] multiplied by the voltage drop from the input to the output) is simply discarded, as heat.
-The usual internal [[circuit]]ry is that a combination of a [[transistor]] and the load (output) are used as a voltage divider network; the [[emitter]] of the transistor is connected to the output, and the [[collector]] to the input voltage. The current through the transistor's [[base]] is adjusted so that the voltage drop across the load is what is desired; the rest will be dissipated in the transistor.
+The usual internal [[circuit]]ry is that a combination of a [[transistor]] and the load (output) are used as a voltage divider network; the [[emitter]] of the transistor is connected to the output, and the [[collector]] to the input voltage. The [[current]] through the transistor's [[base]] is adjusted so that the voltage drop across the load is what is desired; the rest will be dissipated in the transistor.
-Depending on the circuit details, in linear supplies the output voltage is often dependent on the input voltage (and directly related to it), so if the latter varies, so will the former.
+Depending on the circuit details, in linear supplies the output voltage is often dependent on the input voltage (and directly related to it), so if the latter varies, so will the former. Simple linear supplies are thus unsuited to applications where precise regulation of the output voltage is needed.
 Due to their low efficiency, in high-power applications they have generally been replaced by [[switching power supply|switching power supplies]].
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@@ Line 1: / Line 1: @@
 A '''linear power supply''' is one that uses purely [[analog]] techniques (i.e. internal [[signal]]s with [[voltage]]s with continuously varying values) to convert input power to output, at the voltage needed. (The internal devices operating in this mode are said to be operating in their 'linear' mode.)
-Linear supplies are generally inefficient since if they take in a given [[current]] (at the supply voltage), then without using a [[transformer]] (which only works with [[alternating current]]), there is no easy way to produce more than that much output current  (since the number of [[electron]]s in the current is fixed, and 'electrons out' must equal 'electrons in').
+Linear supplies are generally inefficient because of the [[VI conversion]] issue; since linear supplies are usually quite simple internally, they usually do not have any mechanism for this. Generally, the extra power (the actual amount is given by the [[ampere|amperage]] multiplied by the voltage drop from the input to the output) is simply discarded, as heat.
 The usual internal [[circuit]]ry is that a combination of a [[transistor]] and the load (output) are used as a voltage divider network; the [[emitter]] of the transistor is connected to the output, and the [[collector]] to the input voltage. The current through the transistor's [[base]] is adjusted so that the voltage drop across the load is what is desired; the rest will be dissipated in the transistor.

@@ Line 1: / Line 1: @@
-A '''linear''' power supply is one that uses purely [[analog]] techniques (i.e. internal [[signal]]s with [[voltage]]s with continuously varying values) to convert input power to output, at the voltage needed. (The internal devices operating in this mode are said to be operating in their 'linear' mode.)
+A '''linear power supply''' is one that uses purely [[analog]] techniques (i.e. internal [[signal]]s with [[voltage]]s with continuously varying values) to convert input power to output, at the voltage needed. (The internal devices operating in this mode are said to be operating in their 'linear' mode.)
 Linear supplies are generally inefficient since if they take in a given [[current]] (at the supply voltage), then without using a [[transformer]] (which only works with [[alternating current]]), there is no easy way to produce more than that much output current  (since the number of [[electron]]s in the current is fixed, and 'electrons out' must equal 'electrons in').
@@ Line 5: / Line 5: @@
 Generally, the extra power (the actual amount is given by the [[ampere|amperage]] multiplied by the voltage drop from the input to the output) is simply discarded, as heat.
-The usual internal [[circuit]]ry is that a combination of a [[transistor]] and the load (output) are used as a voltage divider network; the [[emitter]] of the transistor is connected to the output, and the [[collector]] to the input voltage. The current through the transistor's [[base]] is adjusted so that the voltage drop across the load is as desired; the rest will be dissipated in the transistor.
+The usual internal [[circuit]]ry is that a combination of a [[transistor]] and the load (output) are used as a voltage divider network; the [[emitter]] of the transistor is connected to the output, and the [[collector]] to the input voltage. The current through the transistor's [[base]] is adjusted so that the voltage drop across the load is what is desired; the rest will be dissipated in the transistor.
-Depending on the circuit details, in linear supplies the output voltage is often dependent on the input voltage (and directly related to it), so if the former varies, so will the latter.
+Depending on the circuit details, in linear supplies the output voltage is often dependent on the input voltage (and directly related to it), so if the latter varies, so will the former.
 Due to their low efficiency, in high-power applications they have generally been replaced by [[switching power supply|switching power supplies]].
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