Op-Amp Challenge: Reliable Peak Power Measurement

May 3, 2023 by Jenny List 14 Comments

As part of our Op-Amp Challenge we’re seeing a wide diversity of entries showcasing the seemingly endless capabilities of these extremely versatile parts. Another one comes from [Joseph Thomas], who when faced with the need to measure the properties of an automotive spark plug, came up with a precision peak detector to hold on to the energy level used when firing it.

It starts with an op-amp buffer feeding a diode and capacitor. The capacitor is charged through the diode and holds the level, which can be read through another op-amp. Finally there’s an opto-isolated transistor to discharge the capacitor before a fresh reading is taken.

It’s a simple enough circuit but a very effective one. The op-amps used are bit old-school FET devices, but aside from the high impedance input their performance is hardly critical. Yet another op-amp circuit to hold in reserve should you ever need to perform this task.

Op Amp Challenge: An Ultra-Cheap PH Sensor Amplifier

May 2, 2023 by Jenny List 19 Comments

It’s rare in 2023 for an instrument to be entirely analog, instead it’s more normal for a front-end to feed the analog-to-digital converter (ADC) in a microcontroller. Typically the front-end will do the job of transforming whatever the output range of the sensor is, and present it to the microcontroller in whatever range it accepts. [David] had exactly this problem with a pH sensor, and rather than buy an expensive module to do the job he designed his own.

The sensor in question produces a relatively tiny voltage of -0.414 to +0.414 volts, and requires a very high input impedance. A FET input op-amp is selected, with the ground of the sensor shifted upwards into the positive range by a voltage divider. This then feeds a second op-amp that amplifies the resulting DC voltage for the microcontroller input.

This circuit is an especially simple op-amp application, and is a typical one for a sensor interface where a DC voltage needs to be brought into range of a microcontroller. If you’re not used to op-amp circuits then take a look, this type of analogue circuit is not difficult and might just save your butt some time.

Want to know more about simple op-amp circuits? Have we got the video for you!

Op Amp Challenge: An Op-Amp Buck Regulator

May 1, 2023 by Jenny List 10 Comments

Switching regulators have delivered such convenience and efficiency compared to their linear siblings, that it’s now becoming rare to see an old-style three-terminal regulator. Modern designs have integrated to such an extent that for many of us the inner workings remain something of a mystery. It’s still possible to make switching regulators from first principles though, which is what [Aaron Lager] has done by designing a buck regulator from a quad op-amp IC,

It’s an entry in our Op Amp Challenge and it appears to be a work in progress, but the design is solid enough. We’re no fans of the schematic style of representing an op-amp chip as a rectangle rather than individual op-amps, but it’s simply a PWM generator with a final op-amp used as a driver for the usual diode-inductor-capacitor network. We’re guessing that the op-amp driver won’t make this the most powerful of switchers, but in this case that’s hardly the point. Build this if you’re interested in taking an op-amp out of its normal sphere, or if you’re interested in the workings of a buck converter.

Need more in the way of switching regulators from first principles? We’ve got you covered, with the ultimate regulator kit of parts, the Fairchild UA723.

Hackaday Prize 2023: The Assistive Tech Challenge Starts Now

April 26, 2023 by Tom Nardi 1 Comment

We’d all love to change the world and make it a better place, but let’s be honest…that’s a pretty tall order. Even the best of ideas, implemented perfectly, can only do so much globally. But that doesn’t mean the individual can’t make a difference — you just need to think on a different scale. If improving everyone’s life is a bit out of reach, why not settle for a smaller group? Or perhaps even just one person?

That’s precisely what we’re looking for in the Assistive Tech Challenge of the 2023 Hackaday Prize. In this Challenge, we’re asking the community to come up with ideas to help those with disabilities live fuller and more comfortable lives.

Whether you help develop an improved prosthesis that could benefit thousands, or design a bespoke communication device that gives a voice to just a single individual, it’s hard to imagine a more noble way to put your skills and knowledge to use.

Looking to lend a hand? You’ve got from now until May 30th to enter your Assistive Tech project. It doesn’t matter what kind of impairment it focuses on — so long as it helps somebody work, learn, or play, it’s fair game to us.

The ten finalists for this Challenge will be announced around June 12th, but you’ll have to wait until Hackaday Supercon in November to find out which projects take home their share of the more than $100,000 in cash prizes graciously provided by sponsors Digi-Key and SupplyFrame.

Continue reading “Hackaday Prize 2023: The Assistive Tech Challenge Starts Now” →

Op Amp Contest: A Slice Of The ’70s

April 25, 2023 by Jenny List 7 Comments

The 1970s was a great time to be an electronics hobbyist, as a whole new world of analogue integrated circuits was coming down in price while new devices would appear to tempt the would-be constructor. Magazines and project books were full of simple circuits to do all manner of fun things, including many synthesizers and sound generators.

We’re reminded of those days by [Burkhard Kainka]’s triggered sound generator, which couples an op-amp timer to another op-amp phase shift oscillator to produce a sound described as “the unwilling meowing of a cat, which does not want to be disturbed“. Yes, we did make things like this back in the day.

The timer is triggered by a few millivolts on its input, which can come from a bit of mains hum or a flash of light to an LED operating as a photodiode. This provides enough DC voltage to the input of the phase shift oscillator to start oscillation, and in turn the oscillator drives a piezo speaker. It’s a fun little project, it shows that a microcontroller isn’t always needed to make something work, and maybe those of you without the experience of a 1970s childhood can learn a little bit of analogue magic from it. Need to know op-amps better? Read our primer!

A High Precision ADC That You Can Understand!

April 21, 2023 by Jenny List 8 Comments

In a world where an analogue to digital converter is all too often an integrated peripheral buried inside a microcontroller, it’s easy to forget how simple these devices can be when built from first principles. An entry in our Op-Amp Challenge from [NNNI] demonstrates this perfectly, it’s a high resolution multi-slope ADC for instrumentation purposes, constructed using a mixture of op-amps, logic chips, and a Raspberry Pi Pico. Best of all, it’s easy to understand, so there’s little of that analogue mystique to worry about.

This type of ADC measures an analogue value by counting how long it takes to charge a capacitor to that voltage. A simple version that measures charge time has a few drawbacks, so this project goes from single slope to multi slope by measuring both charge and discharge times compared to the voltage. Pay attention to component matching and reference stability, and such a design can offer a very high resolution measurement.

The value in this project lies not only in the design itself, but also in the extremely comprehensive description of its operation, which should teach most readers a thing or two. That curvy-line PCB is rather nice, too. We used single slope ADCs to read analogue joysticks back in the day, but we certainly learned something here. Want to see another? This isn’t the first dual slope ADC we’ve seen.

Congratulations Low-Power Winners

April 13, 2023 by Elliot Williams 13 Comments

Congratulations to the winners of the 2023 Hackaday.io Low Power Contest! We challenged you to show us how much you could do with how little, and you did not disappoint. Our judges have put their heads together, and thanks to Digi-Key, our contest sponsor, the top three entries will be taking home a $150 gift certificate for yet more hacking supplies.

We saw a great diversity of ideas here, all on the low-power theme. So without further ado…

The Prize Winners

[Christoph]’s Ultra Low Power RF-Sensor arose out of necessity. Having just repaired a shower drain, he couldn’t be sure that it wouldn’t start leaking again at some point in the future, but couldn’t go ripping up the floor under the shower tray every week to check. He needed a remote moisture sensor that would do the job for a long time with no intervention.

This superb solution combines an Atmel ATmega328P, an HDC1080 humidity sensor, a 433 MHz radio transmitter, and an RTC to keep power consumption super-low when everything else is shut down. Idling at 600 nA total most of the time, taking a reading every 15 minutes, this device should last for 12 years, and it’s been installed and running for five so far, so we’d say that it’s already proven itself very worthy of taking home the prize here.

[BleakyTex]’s Compact, low-power Geiger counter is absolutely the lowest power Geiger counter we’ve ever seen and maybe also the cutest. With the ambitious goal of running up to two years on two tiny LR44 batteries and a proven runtime of about six months by now, this is the radiation detector you can take with you every day, should you need to. The key is a custom HV section that’s designed for efficiency and the screen – even today, it’s still hard to beat the low power consumption of the humble LCD screen. All this, and it still makes those satisfying clicks when it’s enabled. [BleakyTex] says he might make a kit from this, and we absolutely hope he does!

[mircemk]’s Microwatt Pulse Motor took one of our suggestions in the announcement of the contest and ran with it. This eight-pole handmade electric motor doesn’t actually do anything other than spin, but it does that when hooked up to a literal potato. Pulling around 40 mA at 600 mV, it can easily run on solar power with enough power left over to charge up a battery for when the sun doesn’t shine. All of this is made with extremely simple circuitry and parts scavenged from old relays with a sewing needle held up by a magnet for the bearing. This is pure ingenuity and a sweet low-power demo.

Continue reading “Congratulations Low-Power Winners” →