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RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

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Re: RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

#21

Post by K0balt »

walrus01 wrote: post #17
K0balt wrote: post #16

Earlier quoted context omitted.

Mmmmmmmmmmhhh. Maybe better to damage A battery than to have a drone fall out of the sky? Also most protected cells have modest current capabilities, and might not be enough for many drone applications. By its nature, MUAVs tend to push batteries to their limits and lifecycles tend to be limited. A battery that does mission X must have a maximum weight and a minimum capacity, and a minimum current spec. If you increa…

So I was referring specifically to this phone hardware project and to flashlights, which don't fly... But my thoughts on drones are also that it's very different if you're building consumer class things that are meant to be re-used or what's going on in ukraine right now. They're using high amp rate cylidrical 18650 and 21700 cells in 6S2P and 6S3P packs for one way trip munition drones where you don't particularly c…

If you’re getting into bigger (kg+) drones, it starts to make sense to shoot for 100cycle+ (and for 10kg+, 1000 cycle-ish) lifespans. The economics and the physics work out. But for very tiny systems like the single cell drone featured, the equation starts to favor squeezing every last drop of energy reasonably possible, which means that you can easily get caught out downwind or “stayed to get a few too many pictures” and end up hitting the safety walls. (Partly because the risk of doing so is proportional to the size)

Re: RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

#22

Post by spockz »

shrx wrote: post #15

We have a similarly converted rotary phone at my local astronomy club's observatory, used to receive visitors. It's driven by an arduino if I remember correctly. The main issue is that the sound quality of its built-in speaker is quite poor, especially compared to modern cell phone speakers we're used to nowadays, with a narrow frequency window and frequent echoes.

Interesting. I remember voice clarity being exceptional on old handsets and being really subpar on gsm and later. Only now we FaceTime voice and discord the quality seems to be coming back.

How can that be if the speakers in phones ubiquitously were so bad?

Re: RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

#24

Post by ssl-3 »

bux93 wrote: post #23

Cool! But who remembers phone numbers anymore? Maybe a small screen that you can navigate by dialling 1 (down), 5 (up) and 0 (select) would be a cool add-on (after dialling 0 or 411 to reach the operator perhaps).

The next move is to go further back in user interfaces: To place a call, pick up the phone and dial 0 or turn the crank to ring the operator.

Have a bot do the rest, exactly like a telephone operator.

Re: RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

#25

Post by ssl-3 »

mikeweiss wrote: post #18
ralferoo wrote: post #14

Accepting 5V over the RJ-11 jack seems asking for trouble. Someone is going to plug it into a regular phone socket at some point, so it needs to be capable of surviving at least 60VAC. Even if a secondary pair is used, there are so many different wiring standards in use, it'll end up plugged into something live sooner or later.

Dunno about you but I don't know anyone with live RJ-11 jacks in their house anymore.

It's been a very long time since I had a cable modem that didn't have a pair of 4P4C (aka RJ11 or POTS) jacks on the back. These exist to make available the VOIP service that I haven't wanted for decades.

Others using this same enormous, American ISP probably have similarly-equipped gear.

But I must admit that it has also been a very long time since I connected anything there. I don't know if they supply 48v talk battery or not when the modem has a data-only configuration.

Re: RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

#26

Post by ssl-3 »

K0balt wrote: post #16
walrus01 wrote: post #12

For the 21700 cell if you want to do this without spending a lot on batteries, but also be sure that any misconfigured hardware can't drain the battery below a damage threshold, use a button top protected 21700 cell. Here's a good 'house brand' one that is popular with 21700 flashlights. https://liionwholesale.com/collections/batteries/products/pr...

Mmmmmmmmmmhhh. Maybe better to damage A battery than to have a drone fall out of the sky? Also most protected cells have modest current capabilities, and might not be enough for many drone applications. By its nature, MUAVs tend to push batteries to their limits and lifecycles tend to be limited. A battery that does mission X must have a maximum weight and a minimum capacity, and a minimum current spec. If you increa…

What are the chances of this telephone falling out of the sky due to battery failure?

Re: RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

#27

Post by Someone »

spockz wrote: post #22
shrx wrote: post #15

We have a similarly converted rotary phone at my local astronomy club's observatory, used to receive visitors. It's driven by an arduino if I remember correctly. The main issue is that the sound quality of its built-in speaker is quite poor, especially compared to modern cell phone speakers we're used to nowadays, with a narrow frequency window and frequent echoes.

Interesting. I remember voice clarity being exceptional on old handsets and being really subpar on gsm and later. Only now we FaceTime voice and discord the quality seems to be coming back. How can that be if the speakers in phones ubiquitously were so bad?

Could be that it wasn’t bad but has gotten bad because of aging of the speaker, capacitors, resistors, etc.

Re: RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

#28

Post by alnwlsn »

shrx wrote: post #15

We have a similarly converted rotary phone at my local astronomy club's observatory, used to receive visitors. It's driven by an arduino if I remember correctly. The main issue is that the sound quality of its built-in speaker is quite poor, especially compared to modern cell phone speakers we're used to nowadays, with a narrow frequency window and frequent echoes.

In contrast, I've been messing around with some old analog phones and VOIP stuff recently, and I've been blown away with how good the quality is over what I was expecting. The audio bandwidth is low yes (it's G.711u, so 8 KHz), but the actual quality is great, with no hyper-compression artifacts or over-applied background noise filters. And yes this is on the original 60's carbon microphones.

The regular phone calls I normally make on my cell still all sound like they are underwater for some reason, except for those rare times when the better connection is actually working.

Re: RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

#29

Post by aftbit »

mikeweiss wrote: post #18
ralferoo wrote: post #14

Accepting 5V over the RJ-11 jack seems asking for trouble. Someone is going to plug it into a regular phone socket at some point, so it needs to be capable of surviving at least 60VAC. Even if a secondary pair is used, there are so many different wiring standards in use, it'll end up plugged into something live sooner or later.

Dunno about you but I don't know anyone with live RJ-11 jacks in their house anymore.

I've got them, powered by an Adit 600 in my basement.

Re: RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

#30

Post by aftbit »

K0balt wrote: post #16
walrus01 wrote: post #12

For the 21700 cell if you want to do this without spending a lot on batteries, but also be sure that any misconfigured hardware can't drain the battery below a damage threshold, use a button top protected 21700 cell. Here's a good 'house brand' one that is popular with 21700 flashlights. https://liionwholesale.com/collections/batteries/products/pr...

Mmmmmmmmmmhhh. Maybe better to damage A battery than to have a drone fall out of the sky? Also most protected cells have modest current capabilities, and might not be enough for many drone applications. By its nature, MUAVs tend to push batteries to their limits and lifecycles tend to be limited. A battery that does mission X must have a maximum weight and a minimum capacity, and a minimum current spec. If you increa…

Who mentioned drones? This is for a phone.
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