Op Amp - Revision history

Adamcolton: /* Real Op Amps */

2020-07-08T14:15:32Z

Real Op Amps

← Older revision		Revision as of 14:15, 8 July 2020
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	== Real Op Amps ==		== Real Op Amps ==

	I have a 741 and the lowest it will go is to 1.9V, but it can go all the way up to V+. Which kind of sucks, because it can't easily drive N fets.		I have a 741 and the lowest it will go is to 1.9V, but it can go all the way up to V+. Which kind of sucks, because it can't easily drive N fets. The quad op amps I have are ??? and they go down just a few mV.

	I tested this on a 2n7000 and the active region is really around a Gate-Source voltage of 1.2v, so the 741 doesn't go low enough.		I tested this on a 2n7000 and the active region is really around a Gate-Source voltage of 1.2v, so the 741 doesn't go low enough.

			I came up with a few solutions. One is to send the output of the op amp through a voltage divider. Even better was a diode (an LED worked well because it has a large voltage drop). This drops the output voltage to below the 1.2V of the N-FET base. The other solution was to drive the N-FET with a PNP BJT. However, since the op amp doesn't go all the way to the top rail, I can't turn the BJT all the way off so I have to drop the voltage to the emitter. Again a diode works, but if an op amp can be spared, it can be pegged high to provide a reference to the voltage drop.

	[[Category:Electronics]]		[[Category:Electronics]]

Adamcolton: /* Real Op Amps */

2020-07-06T01:38:28Z

Real Op Amps

← Older revision		Revision as of 01:38, 6 July 2020
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	== Real Op Amps ==		== Real Op Amps ==

	I have a 741 and the lowest it will go is to 1.9V, but it can go all the way up to V+. Which kind of sucks, because it can't easily drive N fets. ~~This may not be an issue, it looks like 2V~~ is ~~essentially off for most N Fets~~. ~~Need to test~~.		I have a 741 and the lowest it will go is to 1.9V, but it can go all the way up to V+. Which kind of sucks, because it can't easily drive N fets.

			I tested this on a 2n7000 and the active region is really around a Gate-Source voltage of 1.2v, so the 741 doesn't go low enough.

	[[Category:Electronics]]		[[Category:Electronics]]

Adamcolton: /* Real Op Amps */

2020-07-05T22:30:05Z

Real Op Amps

← Older revision		Revision as of 22:30, 5 July 2020
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	== Real Op Amps ==		== Real Op Amps ==

	I have a 741 and the lowest it will go is to 1.9V, but it can go all the way up to V+. Which kind of sucks, because it can't easily drive N fets.		I have a 741 and the lowest it will go is to 1.9V, but it can go all the way up to V+. Which kind of sucks, because it can't easily drive N fets. This may not be an issue, it looks like 2V is essentially off for most N Fets. Need to test.

	[[Category:Electronics]]		[[Category:Electronics]]

Adamcolton: /* Real Op Amps */

2020-07-05T16:38:28Z

Real Op Amps

← Older revision		Revision as of 16:38, 5 July 2020
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	== Real Op Amps ==		== Real Op Amps ==
	~~I need to test the op amps I have and see how close to the rails they actually get.~~

	I ~~also need to build~~ a ~~real circuit that uses an op amp~~ to ~~drive a transistor from on~~, ~~through active~~ to ~~off~~.		I have a 741 and the lowest it will go is to 1.9V, but it can go all the way up to V+. Which kind of sucks, because it can't easily drive N fets.

	[[Category:Electronics]]		[[Category:Electronics]]

Adamcolton: /* Real Op Amps */

2020-07-01T19:44:10Z

Real Op Amps

← Older revision		Revision as of 19:44, 1 July 2020
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	== Real Op Amps ==		== Real Op Amps ==
	~~Don't work well near~~ the ~~terminals~~.		I need to test the op amps I have and see how close to the rails they actually get.

	* lm324 :		I also need to build a real circuit that uses an op amp to drive a transistor from on, through active to off.
	* lm741

	[[Category:Electronics]]		[[Category:Electronics]]

Adamcolton at 19:15, 1 July 2020

2020-07-01T19:15:31Z

← Older revision		Revision as of 19:15, 1 July 2020
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	== Current Sensor ==		== Current Sensor ==
	I had to do the math analysis to understand this. Configuration is a differential amplifier.		I had to do the math analysis to understand this. Configuration is a differential amplifier.

			== Real Op Amps ==
			Don't work well near the terminals.

			* lm324 :
			* lm741

	[[Category:Electronics]]		[[Category:Electronics]]

Adamcolton at 23:43, 7 February 2018

2018-02-07T23:43:16Z

← Older revision		Revision as of 23:43, 7 February 2018
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	https://en.wikipedia.org/wiki/Operational_amplifier_applications		https://en.wikipedia.org/wiki/Operational_amplifier_applications

			* http://4.bp.blogspot.com/-J97VeAMfTS8/VarSHHscsOI/AAAAAAAAI4A/nuwYvkHMt2Y/s1600/1044843_565709233486797_1067282875_n.jpg
			* https://mysite.du.edu/~etuttle/electron/circ23.gif
			*

	== Comparator ==		== Comparator ==

Adamcolton: /* Current Sensor */

2017-10-16T01:50:07Z

Current Sensor

← Older revision		Revision as of 01:50, 16 October 2017
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	== Current Sensor ==		== Current Sensor ==
	I had to do the math analysis to understand this.		I had to do the math analysis to understand this. Configuration is a differential amplifier.

	[[Category:Electronics]]		[[Category:Electronics]]

Adamcolton at 01:49, 16 October 2017

2017-10-16T01:49:31Z

← Older revision		Revision as of 01:49, 16 October 2017
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			https://en.wikipedia.org/wiki/Operational_amplifier_applications

	== Comparator ==		== Comparator ==
	Simplest op amp circuit		Simplest op amp circuit

Adamcolton: Created page with "== Comparator == Simplest op amp circuit == Non-Inverting amplifier == Amplifies the input voltage. Cannot go below unity. For high power, output can go through a transistor..."

2017-10-16T01:48:34Z

Created page with "== Comparator == Simplest op amp circuit == Non-Inverting amplifier == Amplifies the input voltage. Cannot go below unity. For high power, output can go through a transistor..."

New page

== Comparator ==
Simplest op amp circuit

== Non-Inverting amplifier ==
Amplifies the input voltage. Cannot go below unity.

For high power, output can go through a transistor.

== Schmitt Trigger ==
Uses positive feedback.

== Current Sensor ==
I had to do the math analysis to understand this.

[[Category:Electronics]]