Many consumer grade USB power banks come with a built-in automatic shutdown circuit. Light loads, such as the nominal 6.8 μA drawn by a portable MP3 player, are not enough to prevent shutdown. To compensate, this project uses a 555 to nominally pull 100 mA every 5.5 seconds.
( excerpt - read more at
Danke,
Your blatantly obvious approach was the first solution attempted by me. It was eventually, reluctantly, rejected because it doesn't work out so well in practice. Read the link to find out why.
Danke,
Maybe just a capacitor would keep it alive.
forgot the 'u' in microamps.
I thought, what USB can supply 6 AMPS ?!?! :)
boB
It sounds about right - you're probably correct in regards to what most people do. They use their phone to download MP3s from the Inet. OTOH, my phone is used strictly for phone calls, SMS, and photographs. By choice, it never connects to the Inet. A plain MP3 player appeals to me in the same manner as a unix command - it does only one job and it does it well. In this case, it plays MP3s pre-loaded onto an SD card. And it actually is still sold on ebay. There's a link to a retailer on my page.
Upon further reflection, your LED idea certainly works as a replacement for the 555 circuit. It's a tradeoff - LED simplicity versus 555 efficiency. As is, the 555's about 18 times more efficient. It's probably doable to make it 40 - 50 times more efficient.
The simultaneous use of both USB outputs didn't work for me. Nor did the simultaneous use of an external and internal battery. The back of the Power Bank states "Output: 5 V DC, 1 A or 2.1 A." There's two lightening bolts next to one of the USB outputs, while the other has only a single bolt. Presumably the former's for 2A. Anyhow, it seems to imply you can either use one or the other, ???but not both???
Danke,
The back label on my Power Banks boasts it can supply 5 V DC at 2.1 A for 5,000 mAh.
Anyhow, my message is UTF-8 encoded. The question mark between the 6.8 and A is actually a Greek mu character.
Danke,
The Power Bank doesn't show a garbage can with an X through it as is typically found on Li-Ion batteries. For all I know the Power Bank /is/ just a capacitor. It's the perfect size - about half the length of a smart phone. The whole gadget fits nicely into my pocket with plenty of space left over for a small flashlight and a Swiss army knife.
Danke,
I was surprised a couple of years ago when I went to Best Buy to get an MP3 player and they only had one, one piece that is, not one model.
The question remains which would I rather take to the gym and possibly destroy, a $30 SanDisk Jam or a smart phone. Which is more convenient to clip to my t-shirt? Even though I don't have a $1000 smart phone it's still not a hard question.
When the MP3 player is drawing uA, it means that its own internal battery is charged up. Who cares if the external bank shuts down ?
If the MP3 player internal battery is low, it should draw current from the external bank, to recharge, when present.
If your external battery bank is misbehaving, you should consider using another that doesn't.
If the mp3 Player is misbehaving, then ditto.
'Smart' battery electronics are configured, modified and patched by imbeciles.
Portable MP3 players are available that offer trouble-free operation from a single charge, at moderate volume levels, for >12hrs. No fuss - no muss - no bother.
RL
In the light of a new day, my caffeine enhanced neurons now understand your intention to use a capacitor to replace the 555 and not the Power Bank. It probably won't work because MP3 chips seem super sensitive to the slightest power disruption, no matter how short. IOW the Power Bank must first automatically shutdown before the capacitor kicks in. And, most likely, the oh-so-brief, transient voltage droop triggers the MP3 player to replay its current audio track from the beginning.
Danke,
My MP3 contraption was originally connected to a half-depleted Power Bank (too lazy to fully charge it beforehand) with half of its power consumption LED indicators dark. And it's now been used for about fifty hours with no change in indicators. In the end, instead of hours, the Power Bank may last for /seasons/.
My 555 keep-alive is the tail end of a long process. It entailed experimentation on a couple of different MP3 players and Power Banks. It all cases, the simultaneous use of internal and external batteries and/or USB Power Bank ports ended in failure.
My goal never was to advance the state of the art. It was always to simply listen to MP3s during treks and spins, from a SD inserted into a cheap, disposable (eg no tears if lost/broken) MP3 player.
From a metaphysical perspective, my keep-live functions as absurdist, modern art. An attempt to add an old fashioned ON/OFF switch to a device created by an industry with an unhealthy obsession for baroque, Rube Goldbergist switches.
Danke,
Maybe a cap across the UPS ac output will make current that fools the load sensor into thinking there is always a load. The cap will dissipate no power.
It wouldn't be hard to try.
Not a UPS, a power bank. No AC output.
It is a little disappointing; how the original, simple MP3 players disappeared from the local retail market.
I think it was the introduction of early small screens that killed them. Fashion trends are a bitch.
RL
Check out this dusty fool foaming over some trash mp3 player that requires an external battery pack plus some 555 hack nonsense to even stay powered on.
Rediculous.
On a sunny day (Sun, 12 Jun 2022 09:14:24 -0700 (PDT)) it happened a a snipped-for-privacy@gmail.com wrote in snipped-for-privacy@googlegroups.com:
Bull, I have many mp3 capable things, credit card size mp3 / video player, what not, phone But my mp3 player is a 20 year old or so Creative Muvo, runs on an AAA Eneloop battery all day if needed, easy to charge or swap, I concatenated all my favorite music into one long mp3 so it can run unattended for many hours, and is small and simple to use.
I prefer no RF shit next to my head, you see what it can do to people ;-)
Silly
He used a mu symbol, just your newsreader apparently can't handle the way he did that.
Hello Don, you're obviously a handy guy, so why not just open up the power bank, and bypass that 'auto-shut-off' circuitry?
Maybe you use this power back for other uses? So you still want the auto-shut off?
I don't see the logic why that feature is needed in the power bank, anyway. Any electronic device (beyond a simple thing like a light) is likely to have its own auto-shut
-off function.
But you do want to preserve it, then I'd install a simple SPST switch to select bypassed- or native-behavior as you like. cheers, Rich S.
One reason for me to leave the Power Bank unopened is it may open a can of worms. Especially if it uses an undocumented, expoxied, exposed-lead chip to control its charge cycle /and/ perform an automatic shutdown. Also, my tear-down of the MP3 player to remove its battery and USB-B port already sated my appetite to take things apart (for now). :) You didn't comment on my MP3 player. Muchas Gracias. After all, the player's merely an available adjunct to test my keepalive with a field trial.
Although the keepalive functioned as originally intended, the prospect to double its efficiency tempted me to replace R2's original 150 K ohm value with a 300 K ohm. So my page now reflects R2's new value:
Note.
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