Making A Classic Chip From Discretes

A hackspace discussion of voltage regulators within our earshot touched on the famous μA723, then moved on to its competitors. Kits-of-parts for linear regulators were ten-a-penny in the 1970s, it seems. A rambling tale ensued, involving a Lambda power supply with a blown-up chip, and ended up with a Google search for the unit in question. What it turned up was a hack from 2014 that somehow Hackaday missed at the time, the replication by [Eric Schlaepfer] of an out-of-production regulator chip using surface-mount semiconductors when his Lambda PSU expired.

Lambda were one of those annoying electronics companies with a …read more

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Circuit Challenge: Two Transistor 3.3V Regulator

[Kevin Darrah] wanted to make a simple 3.3V regulator without using an integrated circuit. He wound up using two common NPN transistors and 4 1K resistors. The circuit isn’t going to beat out a cheap linear regulator IC, but for the low component count, it is actually pretty good.

In all fairness, though, [Kevin] may have two transistors, but he’s only using one of them as a proper transistor. That one is a conventional pass regulator like you might find in any regulator circuit. The other transistor only has two connections. The design reverse biases the base-emitter junction which results …read more

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Not Your Typical ATX Bench PSU

We know what you’re thinking — yet another scrap PC power supply turned into a bench PSU. But look a little closer and you’ll see a nicely designed linear bench supply that just fits inside a gutted ATX case.

A lot of the items on [Medzik]’s BOM for this build are straight from the scrap bin. The aforementioned ATX supply case is one, as is the power transformer donated by a friend. Modules such as the 30V/2A regulator, the digital volt/ammeter, and a thermostat module to control the fan at higher power settings were all sourced via the usual suspects. …read more

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A Lesson On Zener Regulators

For the longest time, Zener diode regulators have been one of those circuits that have been widely shared and highly misunderstood. First timers have tried to use it to power up their experiments and wondered why things did not go as planned. [James Lewis] has put up a worth tutorial on the subject titled, “Zener Diode makes for a Lousy Regulator”  that clarifies the misconceptions behind using the device.

[James Lewis] does an experiment with a regulator circuit with an ESP8266 after a short introduction to Zener diodes themselves. For the uninitiated, the Zener diode can operate in the reverse …read more

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A Lesson On Zener Regulators

For the longest time, Zener diode regulators have been one of those circuits that have been widely shared and highly misunderstood. First timers have tried to use it to power up their experiments and wondered why things did not go as planned. [James Lewis] has put up a worth tutorial on the subject titled, “Zener Diode makes for a Lousy Regulator”  that clarifies the misconceptions behind using the device.

[James Lewis] does an experiment with a regulator circuit with an ESP8266 after a short introduction to Zener diodes themselves. For the uninitiated, the Zener diode can operate in the reverse …read more

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Current Sink Keeps The Smoke In

One of the most versatile tools on anyone’s work bench, at least as far as electrical projects are concerned, is a power supply. Often we build our own, but after we’ve cobbled together some banana jacks with a computer’s PSU or dead-bug soldered a LM317 voltage regulator to a wall wart, how will that power supply perform? Since it’s not desirable to use a power supply that’ll let the smoke out of everything it powers (or itself, for that matter) a constant current sink, or load, can help determine the operating limits of the power supply.

[electrobob] built this particular …read more

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Get To Know Voltage Regulators with a 723

“Chapter 5; Horowitz and Hill”. University students of all subjects will each have their standard texts of which everyone will own a copy. It will be so familiar to them as to be referred to by its author as a shorthand, and depending on the subject and the tome in question it will be either universally loathed or held onto and treasured as a lifetime work of reference.

For electronic engineers the work that most exemplifies this is [Paul Horowitz] and [Winfield Hill]’s The Art Of Electronics. It definitely falls into the latter category of course books, being both …read more

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DIY Pressure Regulator for Exciting SCUBA

To get a SCUBA certification, a prospective diver will need to find a dive shop and take a class. Afterwards, some expensive rental equipment is in order. That is, unless you’re [biketool] who has found a way to build some of his own equipment. If you’re looking for a little bit of excitement on your next dive, this second stage regulator build might be just the thing for you.

It’s worth noting that [biketool] makes it explicitly clear that this shouldn’t be used on any living being just yet. The current test, though, was at 120 PSI using some soda …read more

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