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Wanted: A 'joule thief' style circuit design...

Started by ~misfit~ September 29, 2019
On 1/10/2019 3:08 PM, ~misfit~ wrote:
> On 1/10/2019 3:04 PM, ~misfit~ wrote: >> On 30/09/2019 8:17 PM, Jasen Betts wrote: >>> On 2019-09-29, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote: >>>> ... that I can use to drain alkaline cells and push the 'charge' into either a lithium-Ion cell >>>> (for a flashlight), a phone or a powerbank. >>>> >>>> I have a combined wireless doorbell - inside/outside thermometer that I quite like. Unfortunately >>>> it won't run on NiMH cells and only uses alkalines down to 1.33v. (It's the only thing I have that >>>> doesn't run on rechargeable cells.) >>>> >>>> The sender uses AAA cells and the receiver uses AA cells and I buy good quality (expensive) cells >>>> to get the longest run-time between changes (as it's a PITA to re-pair them and re-set the >>>> clock in >>>> the receiver too often). I though of converting the receiver to run on a single 14500 Li-Ion cell >>>> (AA size) and a buck regulator or even a wall-wart but that still doesn't solve the issue of the >>>> sender. >>>> >>>> I dislike throwing good quality alkalines away when they still have ~65% of their capacity >>>> remaining but have had enough leak-disasters to not want to put already semi-discharged cells in >>>> remote controllers etc. where they then get forgotten about until things stop working. (I've never >>>> had an Eneloop leak and they run my remotes for about 3 years between charges.) >>>> >>>> So I'd like to make a gizmo that takes a single alkaline and pushes out ~5v through a USB cable >>>> for >>>> as long as the cell has juice, preferably at a reasonable current. I have a few different pre-made >>>> boost modules from the usual suspects but when I tested one the output voltage curve dropped with >>>> the input so that it wasn't very successful. >>> >>> these are cheap and will do it >>> https://aliexpress.com/item/32786144773.html >> >> I've actually already got some of those in my 'module collection'. > > My bad, just checked and I don't have those. I have some of these > <https://www.aliexpress.com/item/32450571426.html> and at first glance I thought they were the same > thing. I really need to 'index' my module collection.
I just ordered 5 of these <https://www.aliexpress.com/item/32830275320.html> They're cheap enough and claim a higher efficiency than the one you linked. If I don't use them for this 'project' they will likely be useful down the track sometime. I can put them in my collection. ;) -- Shaun. "Humans will have advanced a long, long way when religious belief has a cozy little classification in the DSM" David Melville This is not an email and hasn't been checked for viruses by any half-arsed self-promoting software.
SEPIC

WIKI has a page on it that isn't too bad. 
On 2019-10-01, ~misfit~ <shaun.at.pukekohe@gmail.com> wrote:
> On 30/09/2019 8:17 PM, Jasen Betts wrote:
>> maybe you can find some device to run off the partly used batteries, >> a portable radio perhaps. > > Radio? I haven't used one of those in years! However you're right, I think I'll use them in a > flashlight or something that I *do* use. ;) Now I need to decide if buying a new flashlight (when I > have several perfectly fine 18650-powered flashlights) works out better than wasting alkaline cells. > > Cheers,
3 AAAs are smaller than an 18650 and the voltage is about right. you can get adaptors. https://www.aliexpress.com/item/32973004084.html On the other hand the torch may work just fine off a single cell, I've got mostly AA/14500 torches here, they have some sort of buck/boost device. -- When I tried casting out nines I made a hash of it.
On Sunday, September 29, 2019 at 7:07:22 PM UTC-7, ~misfit~ wrote:

> > On Mon, 30 Sep 2019 00:19:07 +1300, ~misfit~ > > <shaun.at.pukekohe@gmail.com> wrote:
> >> I have a combined wireless doorbell - inside/outside thermometer that I quite like. Unfortunately > >> it won't run on NiMH cells and only uses alkalines down to 1.33v.
> The sender uses two AAA cells and is very tightly packaged. Also it's waterproof as it's outside in > the elements so I don't want to mess with it too much.
It's bad design if it requires 1.33V; either bypass the battery terminals with a capacitor (that'll lower the impedance, if it's a logic-glitch that makes it malfunction) or consider using three cells in series (if it works on 3V, it should be OK for 4.5... maybe). A redesign of the circuit might be in order, except it's a consumer-grade package with cryptic labels and 'instructions'. Gluing it into a bigger waterproof box isn't too hard.
On Mon, 30 Sep 2019 00:19:07 +1300, ~misfit~
<shaun.at.pukekohe@gmail.com> wrote:

>it won't run on NiMH cells and only uses alkalines down to 1.33v.
You need a batteriser! -- RoRo
On 5/10/2019 6:12 AM, Robert Roland wrote:
> On Mon, 30 Sep 2019 00:19:07 +1300, ~misfit~ > <shaun.at.pukekohe@gmail.com> wrote: > >> it won't run on NiMH cells and only uses alkalines down to 1.33v. > > You need a batteriser!
... like I need a hole in the head. ;) -- Shaun. "Humans will have advanced a long, long way when religious belief has a cozy little classification in the DSM" David Melville This is not an email and hasn't been checked for viruses by any half-arsed self-promoting software.