Is a self-powered transmitter possible?

[k.udhay]

This video claims that the transmitter is self powered and hence needs no battery or other electric connection.

Is this possible? I have never come across an electronic device that runs self-powered.

Couple of things I think might happen here:
1. A solar cell in the transmitter?
2. Everytime when someone presses the switch, it converts some of that energy to electricity? Like piezoelectric for instance?

Pl. share your comments.

 

[berkeman]

2. Everytime when someone presses the switch, it converts some of that energy to electricity?

A company that I worked for has self-powered switches that transmit an RF message sequence when pressed. They use a snap spring mechanism and an induction coil to convert the button press to electrical energy to do the transmission.

https://www.easyfit-controls.com/

https://www.easyfit-controls.com/portfolio/easyfit-wireless-switch-esrp-edrp/

 

[k.udhay]

Thank you so much!

 

[russ_watters]

My GF got a couple of these so she could avoid some light switch wiring(similar product). I think they are piezoelectric.

 

[jbriggs444]

$2.69 at Staples.

 

[Vanadium 50]

Is this possible? I have never come across an electronic device that runs self-powered.

https://en.wikipedia.org/wiki/Crystal_radio

 

[tech99]

A possible way of doing it is to have a receiving antenna, a frequency doubling diode and a transmitting antenna. This system is used/was proposed for passive car collision devices, built into the number plate.

 

[Tom.G]

A possible way of doing it is to have a receiving antenna, a frequency doubling diode and a transmitting antenna.

That method was (still is?) used in stores for anti-theft alarms. If you have walked between large vertical loops positioned next to entry/exit doors, then you have been inspected.

Cheers,
Tom

 

[DaveC426913]

Is this how some proximity swipers work? I was thinking about a gas station swipe card, and I surmised that it was powered by the card holder sweeping the card through a magnetic field. That would set up a current in a wire in the card which could then transmit its data to the reader.

I don't know if this is how they actually work, or used to work, but can a chip on a card be powered by movement?

I assumed that's why one needed to swipe them fast. Too slow and it doesn't produce enough magnetically-induced current.

I was younger then.

 

[Tom.G]

I don't know if this is how they actually work, or used to work, but can a chip on a card be powered by movement?

The reading station transmits a carrier that the card receives for power.
The card then transmits its indentity my by changing the loading on its receiving antenna.

The reading station also receives the field that it transmitted, and thus detects the changes in field strength caused by the variable loading of the card.

(Klever, these Enkineers.)

Cheers,
Tom

 

[DaveE]

OK, first feel I must state the obvious: nothing that actually does anything is self powered, at least not for very long. IDK, something about thermodynamics and PMMs. But y'all already know that.

Look into RFID. It's a real thing. It's been around for quite a while. Maybe the earliest, simple version was the anti-shoplifting tags on clothes and such. Then it graduated to credit cards, warehouse inventory, identifying lost dogs, and the toll collection on our bridges and freeways. It's nearly everywhere now.

https://en.wikipedia.org/wiki/Radio-frequency_identification

 

[Vanadium 50]

OK, first feel I must state the obvious: nothing that actually does anything is self powered, at least not for very long. IDK, something about thermodynamics and PMMs. But y'all already know that.

Yes we did. Nobody is talking about magic.

But it is possible to run low-powered devices with no obvious source of power. That's clearly what is meant - nobody is arguing for PMM. Prox cards and anti-theft devices are examples of devices that do not require obvious power sources.

If you want scary, there is work on powering continuous glucose monitors with blood instead of batteries.

 

[Vanadium 50]

I also know that people are working on printing labels with conductive ink to do something similar. The use case is inventory - a box goes through a scanner and it reports whats in the box.

 

[russ_watters]

Since we're expanding the scope: https://en.m.wikipedia.org/wiki/Sound-powered_telephone

 

[jbriggs444]

Since we're expanding the scope: https://en.m.wikipedia.org/wiki/Sound-powered_telephone

Worked example:

 

[DaveE]

If you want scary, there is work on powering continuous glucose monitors with blood instead of batteries.

That doesn't scare me. There should be lots of "free" energy in a living body. Much better than surgery just to replace a battery, which I had to do for a different implant many years ago.

 

[Averagesupernova]

There should be lots of "free" energy in a living body.

Depends on how you look at it. I'd prefer a battery for a pacemaker for instance. The poorer ones health is, the less energy there is likely available to supply a device intended to improve ones health.

 

[DaveE]

Depends on how you look at it. I'd prefer a battery for a pacemaker for instance. The poorer ones health is, the less energy there is likely available to supply a device intended to improve ones health.

Better for measuring devices like a glucose monitor than a device that has to actually do regular work, like a drug pump or pacemaker. Maybe a hybrid system with a small battery that is charged with energy harvesting would be good.

 

[Vanadium 50]

The idea "this is a glucose monitor; it will slowly be eating you" gives me the heebie-jeebies. But I agree, there is a difference between something that is supposed to be diagnostic and supposed to be therapeutic.

Right now, I believe battery technology is more advanced than the monitoring, so it's a non-issue. This may change. Indeed, if you could power it with glucose, you might be able to combine functions into a single unit.

 

[jbriggs444]

The idea "this is a glucose monitor; it will slowly be eating you" gives me the heebie-jeebies.

I dump a heck of a lot more blood into the vials at LabCorp in one visit than my continuous glucose monitor samples over the course of a year.

Changing the monitors every ten days is a pain. Especially when you botch a couple and the supplier meters you with exactly 90 days worth.

 

[Vanadium 50]

You can argue that I shouldn't get the heeboe-jeebies, but I do.

How long is your transmitter/battery good for? I know it varies, but the units are in what, months? There is also the issue of range - you probably get a reasonably BT range, but you probably only really need a few feet. The receiver can be a repeater, and that you can charge like anything else.

As I mentioned earlier, the utility depend on the relative longevity of the parts: if the battery lasts 10x as long as a sensor, it's pointless. If its the other way, it's not.

 

[gmax137]

if you could power it with glucose, you might be able to combine functions into a single unit.

Maybe a klever enkineer can make one that charges up its battery when glucose is high, thus lowering the glucose? Lol.

 

[gmax137]

Maybe a klever enkineer can make one that charges up its battery when glucose is high, thus lowering the glucose? Lol.

Thinking further on this. Let's say you want to reduce the glucose level by 100 mg/dL (bring it from 200 to 100, say). Since the body has about 5 liters of blood, that works out neatly to 5 grams of sugar to be removed.

The diet books show a gram of sugar has about 4 calories. But these are kilo-calories, so our 5 grams contains 20,000 calories, or 23 watt-hours.

A typical cell phone battery is about 15 wh.

So, maybe we can operate the glucose digester AND charge our cell phone at the same time.