{111} The Beloved LM723 Voltage Regulator - Implementing Overcurrent Foldback & Overvoltage Crowbar

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8 ай бұрын

The 723 voltage regulator was a primary linear power supply controller for decades after it was introduced in the late 1960s. In the PROMPT 48 it is used as the primary 5V controller with current feedback, as well as a crowbar to trip a SCR based over voltage protection circuit.
This video shows the implementation of a 723 voltage regulator as used in the PROMPT 48. As implemented in the PROMPT, this is a little past textbook example of overcurrent foldback and over voltage crowbar.
Idea of using bridge to visualize circuit: • Fold Back Current Limi...

Пікірлер: 13

@zxborg9681 4 ай бұрын

Good explanation of the 723. I have a 30 amp amateur radio supply that is based on a 723 and a quad set of chunky 2N3055's. But it seems the designers took some shortcuts and I accidentally blew it up when I shorted it momentarily. Found the NPN bank had no emitter resistors to prevent thermal runaway, but I also think they skipped some of the limit and foldback features in the regulator itself. Now I know I can tweak the circuit to make the thing safer to use. Thanks for going through this in such an easy to follow way.

@HelloWorldETX 4 ай бұрын

Glad you found it useful. Best of luck with your supply.

@jackrubin 4 ай бұрын

Appreciate the deep dive and historical perspective - thanks for the revisiting the time when the 78/79xx family was the latest and greatest.

@HelloWorldETX 4 ай бұрын

wait.... the 78xx/79xx family *still* isn't the greatest?

@dagobertkrikelin1587 8 ай бұрын

Great video!

@HelloWorldETX 8 ай бұрын

Thank you. The LM723 has a long future ahead, I hope the next generation appreciates it as much as we did.

@ramanarao32 3 ай бұрын

Hello Hello world!!! can you suggest me -15V,3A regulator circuit configuration using LM723 with adjustable current limit. Thanks. All circuits given in the LM723 app notes omit current limit for negative regulators.

@HelloWorldETX 3 ай бұрын

Just like an isolated bench power supply, the + and - can be connected either way. so if you have a completely floating design, you can ground either the - side and it becomes a positive supply, or ground the + side and it becomes a negative supply.

@BradHarrison-lw4my 6 ай бұрын

Can you help me? I need 105 vdc with 30 amps, I have contacted the manufacture they never helped. I want to use this power supplies. For a bass amp. I get stuck on the formulas. I have the lm723cn from TI, I used the figure they recommend from the data sheet for 100vdc with the resisters recommended to bias the 723 I can not figure it out. Can you please help? Brad

@HelloWorldETX 6 ай бұрын

Hi Brad, Audio amplifier power supplies are not really my bailiwick.

@stevensexton5801 8 ай бұрын

I'm only getting 360p video. :(

@HelloWorldETX 8 ай бұрын

It only uploaded a few minutes ago. KZfaq starts at the lowest resolution and processes upwards. it will take it a few hours before finally up to HD.

@weedlordbonerhitlerii3862 8 ай бұрын

my dude I love, love, love the information you are putting out but something is deeply wrong with your audio, IDK if it's your mic, levels, encoding, or what but something is fucked please please consult someone who can help you fix the high frequency clipping and whistling your stuff is painful to listen to but it might be as simple as turning the gain down