You can use transformers to add or subtract AC (lemmings.world)

submitted 4 days ago by PixelPilgrim@lemmings.world to c/196

18 comments fedilink hide all child comments

I'm just following the rules of the community and this has. Been on my mind for the past few days . I used to be able to listen into law enforcement and even automated the process but they upgraded their system and encrypted their system.

Now I'm theorizing how I can track law enforcement different ways one of which is using a direction finding system. i could super technical and order a bunch of parts and have a desktop running all the time or I can try to dumb it down with analog composition.

I think it's cool that you can add AC with a ring of iron and winding wires in a specific way (the other way will subtract it)

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[-] TeraByteMarx@lemmy.dbzer0.com 2 points 2 days ago

Are you my wife lol

[-] fullsquare@awful.systems 19 points 4 days ago

jesse, what the fuck are you talking about. you can't make efficient antenna for UHF using power transformer toroid

[-] PixelPilgrim@lemmings.world 4 points 4 days ago

Yeah I think that transformer would have as a induction filter but I see it constantly in antenna design

[-] fullsquare@awful.systems 6 points 4 days ago

Transformers in antennas are just transformers, but you have to use ceramic cores (ferrites) that would be right for your band. I think that what you might be trying to do would be wideband antenna of some sort, but for UHF which is likely in this case, I'd recommend you some kind of log-periodic antenna instead (it just works, directional) or some kind of spiral antenna (it just works, nondirectional). You can make both of these at home

[-] PixelPilgrim@lemmings.world 2 points 3 days ago

Apparently the police operate from 850-860 mhz range and I could use adcock antenna to to get good accuracy and with their frequency being so high wavelength only has like 1% variance. I'm still locked into 2 SDRs for each antenna pairs in the adcock arrangement (I actually think I'd get 2 legitimate directions because SDRs can't match phases). The tldr is adcock doesn't play well with SDRs on paper

I forgot what log-periodic antennas were. it would be better to use directional antenna on a swivel mount and record the highest amplitude at a given angle. As I add antenna I can pick designs with directionality and add sensitivity

[-] fullsquare@awful.systems 4 points 3 days ago* (last edited 3 days ago)

wait, it sounds like you want to use something called four square antenna, but it's usually only made for HF. you'd have to rework it significantly for microwave region http://tm1o.free.fr/4SQ/80m/en_ver_final4-sq_03_04_15.pdf instead of transformers you'd have to use segments of transmission lines with right impedances and some directional couplers, gives direction immediately, no need to compare phase between different SDRs

[-] fullsquare@awful.systems 2 points 3 days ago

Or if you want to get more involved, make a couple of 3el yagis, make a small phased array out of these by plugging them in a directional coupler or 4x4 butler matrix and this will get you two or four receiving directions in a 90 degree segment. If you only want to use that small segment you don't need a LPDA, regular yagi would be fine

[-] Turret3857@infosec.pub 11 points 4 days ago

unrelated to your post, Brave's founder is a transphobic bigot who left Mozilla over being a bigot. Give Cromite a shot (or IronFox if you're feeling adventurous)

[-] shoki@lemmy.world 3 points 3 days ago

why is ironfox adventurous? downloads were bugged for like a week, but everything is working fine for me now. I've had a better experience with ironfox than cromite or vanadium (might be a bit biased though, haven't used chrome-based browsers regularly for like 4 years)

[-] Turret3857@infosec.pub 2 points 2 days ago

Adventurous for people who are used to chromium based browsers, IronFox is my mobile daily driver :P

[-] bytesonbike@discuss.online 2 points 3 days ago

I never heard of cromite.

This looks awesome.

[-] Turret3857@infosec.pub 1 points 2 days ago

It is awesome! I'm thankful for it more and more every day :)

[-] Zgierwoj 12 points 4 days ago

You don't "add AC", the power in the circuit is exactly the same, if you double the voltage you halve the current, its not magic!!!!

[-] vaionko@sopuli.xyz 2 points 4 days ago

Yes, but if you induce current in two coils, you get their sum as the output

[-] PixelPilgrim@lemmings.world 1 points 4 days ago

I should say constructive interfer inside the core of the transformer. I would only care about voltage because I want to hook up my antenna to an adr to scan multiple frequencies.

[-] KazuchijouNo@lemy.lol 13 points 4 days ago

I am confusion

[-] real_squids@sopuli.xyz 9 points 4 days ago

User discovers transformers

[-] Anarki_ 1 points 1 day ago

robots in disguise

this post was submitted on 13 Aug 2025

47 points (100.0% liked)

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