Big Clive's YouTube channel is worth a watch if you like seeing electrical items disassembled and critiqued. It also has the occasional explosion and unusual cooking videos!
* Anticipated explosions managed with the fire containment pie tin.
Big Clive is an electrical engineer from The Isle of Man and has a very unique English accent, complete with local slang and idioms. He’s a very engaging character and passes as entertainment, even without the electronics content. Genuine and occasionally heartfelt and up-lifting. :)
His accent is quite common in Scotland. What's really cool is he has a brother "Ralfy" who also has a Youtube channel specializing in reviewing Whisky:
Big Clive's channel(s) (he has a separate one for live streams) have some of my favorite content on YouTube. He's super down to earth and just has fun with what he does, never taking himself too seriously while being very knowledgeable.
beside clive there's a bunch of special electrical oriented channels:
- photonicinduction (warning, absurd levels of everything up to 11, borderline insane at times, but if you want to see ultra high everything, here's the channel)
- styropyro, spiritual son of the above, but for everything lasers
A few years ago there was some new company (I vaguely recall that it may have been a Kickstarter or similar) touting something like this built into a shell that you could put an AA battery in, and the shell would still fit in most AA slots.
They were way overselling its benefits, claiming you would get something like 6 times as much runtime out of your batteries, and it got a lot of negative reviews and debunking at EE tech sites.
I wish someone would make one of these with that sleeve approach, not as some sort of miracle energy extended scam but rather as a voltage curve adjuster.
A common non-rechargeable alkaline battery starts at about 1.5 volts and over its useful life drops fairly steadily to a little over 1 volt, and then rapidly drops to near zero.
A NiMH rechargeable starts at around 1.4, fairly quickly drops to about 1.3, then over most of its life drops fairly smoothly to about 1.2, then starts dropping faster to around 1.1, then rapidly to near zero.
This is why you can use NiMH in devices designed for alkaline batteries even though nominally alkaline batteries are higher voltage. The device has to actually be designed to handle 1 to 1.5 volts, and the NiMH is in that range for nearly all of its discharge curve.
This is also why some devices designed for alkaline report low battery on NiMH long before the batteries actually need changing, and still report low but useful battery level right up until the device stops working. They are estimating battery life by looking at the voltage and fitting that to the alkaline discharge curve to estimate how far the battery has discharged, and it makes the batter level meter on many devices close to useless if you use NiMH.
It would be great if there were a sleeve you could put around your NiMH batteries that would dynamically raise or lower the voltage as the battery discharges to make it match the alkaline curve. Then your battery level indicator on your devices that were designed only for alkaline would work.
If you search for "1.5V rechargeable", there are lots of lithium ion batteries with electronic voltage regulators now. Some designs will step down to ~1V when nearly depleted, so that low battery indicators still work.
I'm not sure if an NiMH sleeve was ever practical given the space constraints, but it's kind of moot now that better technology exists.
What you're talking about is the Batteriser/Batteroo. It would actually work fine as a voltage stabilizer delivering a constant voltage all the way to the end, but the inefficiencies in power conversion would probably be a major downside (you're losing some energy on the conversion even if the device itself is powered off).
> but the inefficiencies in power conversion would probably be a major downside (you're losing some energy on the conversion even if the device itself is powered off).
You can get around this[0] by starting the power converter in series with the battery (so the load pulls current through it to start it up) although that's: a: complicated, b: more conversion overhead when it is running, and c: rather difficult when you only have 1.5 volts (or 1 volt) to work with initially, compared to eg a 9-volt or 12-volt battery, which exacerbates problems a and b.
I know they are a scam when it comes to their claims of extended battery life. However, the product itself appears to be legit in terms of being a boost converter if that's actually what you need (in most cases you don't, but I guess running certain devices that need exactly 1.5V and can't take the lower ~1.2V from rechargeable cells would make this a legitimate use-case for it).
I built a joule thief flashlight as part of a workshop at a security conference in 2018. We bought a kit that had all the parts, and then soldered them together. For a beginner soldering project, this is excellent.
Unfortunately, I don't think the kit I built is still available.
It would be great if this was available for purchase from somewhere. And if it also included an on off button! I've got a lot of dead batteries (because children toys) and it would be nice using them to get some light for night reading!
Why don't you use rechargeable batteries? I stopped using them in the 90s but switched back a few years ago. More convenient and less wasteful than single use batteries, higher capacity and longer device life than built in batteries.
Rechargeable AA/AAA batteries were always limited to 1.2 volts, which works poorly in some devices. Now you can buy lithium ion cells that regulate down to 1.5 volts, so NiMH is basically obsolete. Alkaline can still make sense for things with multi-year battery life, like remote controls.
> Now you can buy lithium ion cells that regulate down to 1.5 volts, so NiMH is basically obsolete.
NiMH is a lot safer, cheaper, and has slightly better capacity. It's been a few years since first available, but any posters even heard of anyone using 1.5V Li-ion cells? Once you know enough to even be aware of them, you'd be using 3.6V Li-ion instead, so really it's the 1.5V Li-ion that was instantly obsolete, yet still somehow hangs on due to extremely specific circumstances of boutique users that want a flat-regulated 1.5 volts.
Are you sure NiMH has better capacity? You have to look at mAh * voltage (or just mWh) for a fair comparison.
NiMH is safer, and cheaper for now, but those factors are irrelevant when 1.2V is insufficient for a particular device. If a device accepts 3.6V with overdischarge protection, then regular Li-ion makes sense, but there are a lot of 1.5V-3.0V AA/AAA devices out there.
> Are you sure NiMH has better capacity? You have to look at mAh * voltage (or just mWh) for a fair comparison.
Great question. Yes. At least I was, until I just found some newish 1000mAh 14500 cells. Last I knew, 800mAh was the highest capacity around. Ironically, I think in a lot of cases the 1.5V Li-ion cells use Wh rather than Ah to obfuscate the fact that the cell has less considerably less capacity than a 30¢ alkaline. So there is now about the same energy in an AA 1.2V NiMH cell as in a top capacity 14500 3.6V Li-ion cell. But this doesn't stay true for the lifetime of the cell as opposed to a single charge, for the most part because NiMH cells can tolerate 4X the recharges before resistance gets too high.
> NiMH is safer, and cheaper for now, but those factors are irrelevant when 1.2V is insufficient for a particular device. If a device accepts 3.6V with overdischarge protection, then regular Li-ion makes sense, but there are a lot of 1.5V-3.0V AA/AAA devices out there.
In hindsight, the observation I made does not apply much beyond flashlights. You're right, a 3.6V cell is not going to help someone whose device takes 2xAA cells without Dr. Frankenstein's assistance. However, if 1.2V is insufficient to power a device that was designed around alkaline chemistry, then it's a problem with the design, not the chemistry (granted, I have heard stories that NiMH doesn't work in some devices, but this wasn't most devices nor devastating to consumers). Alkaline cells aren't 1.5V for very long, it's a pretty steady discharge curve from ~1.65V down to 1V. So a device with such strict power parameters designed around drawing power from alkaline cells, without taking into account the discharge curve of alkaline chemistry, is thus poorly designed and wasting upwards of a third of your batteries' capacity (if 1.2V no longer works, and an alkaline cell is fully charged at 1.65V).
I agree, NiMH rechargeables are better than alkalines in almost every way. They don't leak and destroy the electronics. They can be recharged 500-1000 times, so they don't end up in a landfill after a single use. They have a really flat voltage curve. They have lower internal resistance, so can provide higher currents than alkalines.
I think the only exception might be in ultra low power devices which last over a year on a single charge. But even then, I am likely to use the more expensive NiMH, because I'm so fed up with leaking alkaline batteries.
Low self-discharge NiMH can last a long time in low power devices.
I've got a pair of first generation AAA Sanyo Eneloops in my bathroom scale. They've been in there for 1028 days. I have a pair in the display unit for a pair of wireless fridge/freezer thermometers. That went 395 days.
I've got first generation AA Panasonic Eneloops currently at 1079 days in one of the fridge/freezer thermometer sensors and 978 days in the other. 539 days in a humidity meter. 544 days in an analog wall clock.
With a good charger (not the ones included in sets of batteries) you can also refresh them through programmed charge discharge cycles if you have batteries that aren't in great shape anymore.
They have so many toys (which use for so little each time) that it ain't really worth it to use rechargeable batteries... I am just buying a lot of normal batteries each time and install them whenever needed. I just don't know what to do with the empty (or seeming empty) ones.
Perhaps off-topic, and this may or may not be a popular sentiment on HN, but maybe they could do with fewer toys? At least fewer battery-operated ones? I mean, each and every one of us should be doing our part to not partake in unsustainable consumerism.
I’ve tried this but it’s really hard to get the rest of the gift-giving family on board. My kids just get way too many toys these days. I use rechargeable almost exclusively though and try to keep on top of pulling them out of disused toys to put into newer toys. If a kid tries to use an old toy that I’ve taken the batteries out of (which rarely happens), I just give them more.
This circuit is intriguing…a single transistor power converter that steps up the voltage to any value the load can take. It’s more like a pulsed current source.
Yes and no (your question is invalid/underspecified), with voltage source (constant voltage), current is consequence of device power demand at required voltage. More power required at a given voltage, more current will flow. Less power required, less current will flow, but voltage stays constant. So, ALL voltage regulators are "dropping" current, so your question could be answered by "any voltage regulator, for example LM7805". But if some device requests some power and your regulator's power source can't provide that power, your voltage will drop.
You mean a voltage regulator? That is possible to build but not with this circuit (Joule thief).
The Joule thief charges an inductor in one half of each cycles, and let’s it discharge into the load in the next half. Inductors like to emit a constant current and will kick up the voltage to maintain the current, so it’s more like a current source. Because it drops to 0 quickly before the transistor starts charging it again, it delivers its output as a series of pulses.
So it’s a pulsed current source. The only way to get a constant voltage out of it is to 1) feed the current into a fixed resistance load 2) filter the output via a capacitor.
I thought about how to make a single transistor voltage source but I gave up. Transistors are so cheap there’s not much point. The world has a bizarre preference for voltage sources (maybe due to the fact that early batteries were DC, or maybe it’s just Edison’s ghost). Most real-world loads have useful outputs proportional to current (LEDs, magnetic fields) and the voltage is just a secondary variable.
I love that it's easily small enough to fit into a flashlight bulb base, which would also make it feasible as a replacement for an emergency flashlight. You might not get a lot of light, but you'd almost always get some.
Curious now whether some of the little garden path solar cell lights use these to get maximum output from 4-5 square inches of cheap solar cell and a small nicad battery.
Reminds me of this video about LED light bulbs that continue to draw power even with the switch off. (Something to do with capacitance of the house wiring, the capacitive coupling is enough to make the bulb glow faintly even with the switch turned off)
What are some of the most practical applications? I work in off-grid energy (solar) and would be interested in when/whether a JT can be more viable than, say, a boost DC/DC converter / linear current booster.
It is a DC/DC converter. It's a basic switching power supply.
I was hoping, from the name, for something that would pick up ambient RF and deliver a milliwatt or so. That would be useful for things that need minimal power and are a pain to connect to a power source.
Such things have been around for decades. There's an Instructable for this.[1] Newer designs try to use more of the available spectrum.[2]
Agreed, though it's an impressively simple DC-DC converter.
A whole milliwatt is a lot to hope for from ambient RF (you can do it if you get lucky or make the device big enough), but it's easy to get from solar cells. The purple amorphous kind are less efficient in sunlight but provide more power under the dimmer lighting we use indoors.
https://www.youtube.com/channel/UCtM5z2gkrGRuWd0JQMx76qA