RF powered flashing stickers from the past

And antenna? https://www.reddit.com/r/nostalgia/comments/cdbdiy/nokia_led_flashing_antennas/ I seem to remember having one while working in noisy factories on my old Nokia.

Almost everyone hade those blinking LED's on their phones in the 90's

--I might be wrong here-- GSM (2G) is a single wideband FM channel broken up into 8 "timeslots" so 8 users can share. (D-amps in the US was 3 timeslots on a narrowband) The RF amplifer would come on only for the 1/8 period and the hard switching on and off, of this transmit power was what was enough to light these. Those antenna ones you mentioned (Nokia 5110) worked well on GSM, but on the D-amps 5120 they didn't work well at all, barely glowing. I even had one which was a laser pointer!

Anton

Yes, but not in the intended manner.

Big Clive

They probably share the same era.

Big Clive

This is from the era when a cell phone on your desk would make your computer speakers make a brr brr brr....brr brr brr.... noise because they were cranking out so much power the speaker leads picked it up.

John Ridley

It'll be a long time before we have a lot of towers and 5G around here. The nearest tower is 3 miles away and we can't even get reliable 3G.

John Ridley

Stick them in a microwave, that'll light them up!

Dennis Smith

OMG. Less than I paid c.1977 not even including inflation! http://www.palcoelectronics.com/p1004202.aspx

Peter Laws

Someone mentioned CBs (in the 90s!!) ... in the '70s, we went through a brief fad of "Tenna Toppers". Amazing what markup you can get for a bit of plastic tubing and a neon bulb. Put it on the top of your "tenna" and it glowed when you transmitted. Played hell with your antenna impedance, of course, but who cared when you were *that* cool?

Peter Laws

Very basic explanation: The power is in the electromagnetic signal received on the antenna. It is then rectified by the diodes and sent to the LED(s).

I have one of those "fingernail NFC LED" things and while it's pretty nifty I have no actual use for it. There is something cool about things being powered by RF energy - makes me want a crystal radio but I can't find a decent kit to make.

nowt

Can someone explain how this even works? I am used to electrons coming from somewhere and going somewhere else. Here the power comes from the air and goes to.... nowhere. Are the electrons coming from and going to the air or do they just cycle back and forth like AC?

Mark Trombley

If you configure your phone to only use GSM/2G then the stickers should still flash. We used them in an R&D project some years ago when we implemented our own GSM and GPRS network. Those stickers were neat to indicate "silent SMS" that we sent to the phones (only as a demonstrator case, no illegit intent)

The designs are reminiscent of bygone LSD tab artwork. Slightly weird and wonky.

mj

Back in the mid 90s, I had a CB radio with its magnetic vehicle antenna in my bedroom window. One day in December I noticed a bulb faintly glow on a nearby fairly light string each time I pushed the mic to talk. Sure enough when I touched the base of a small 12v bulb against the antenna,, the bulb would light when transmitting. I recall someone mentioning their CB used to also cause nearby fluorescent tubes to glow.

Seán Byrne

Wearable electronics are great, and if they double as NFC detectors, all the better!

Jeremy Impson

Interesting - I never saw these back in the 90s. RF's not my strong area but diodes are well known as AM detectors even with very low signal levels. Could there be a bit of charge pumping going on?

Mike Page

Clive, your repeated and accurate judgement of their designs brightened my day. Thank you.

Would they work on a modern mobile phone Clive ? You can see how the scare of Mobile phones cook your brains started.

Jeremy Travis

Very interesting. I've recently bought some circular cufflinks that can fit a 20 mm round PCB. I thought about making a board with a small speaker to replicate the dikke-dik-sound of a phone receiving a text or a call in the 90s.

Rasmus

I had a kind of keychain thingy hanging off my phone with an LED in it to warn me in case of call....

They only had use for warning you there was an incoming call when in a very noisy place etc....

I remember thinking phones were modern because you didn't need to extend an antenna out the top. Well, at least we got a massive advancement in class D amplification and fiber lasers out of the whole late 90s telecom boom thing.

that guy

Best wishes for 2022 :). Maybe they choose doublesided tracks so the antenna was as close to the transmitter as possible:).

Mike Weijmans

Cool! You teased this in a live stream! These things were 'the shit' back in the days! You had to have one on tour phone. I had one with very bright white LEDs. 😬

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