#garfield Logs

Oct 30 2021

11:06 AM Tom_L: morning
12:05 PM aandrew: More turns means more flux, higher power transfer I think. Essentially lets you stuff more energy into the core (until you saturate) so you can extract more on the other side
12:05 PM aandrew: rue_mohr: what do you say?
01:27 PM rue_mohr: yes, ok, somehow I have something that says more turns puts you further away from saturation because if your volt-seconds are the same your peak flux is lower
01:27 PM rue_mohr: polprog, your getting into the fiber thing eh?
01:28 PM polprog: yeah
01:28 PM polprog: I might run out of the easy to use SC modules
01:28 PM polprog: so I wanna try experimenting with SFP modules
01:28 PM polprog: ive literally paid $10 for all of them
01:28 PM polprog: and the cages are cheap too
01:42 PM aandrew: polprog: yeah I picked up a shitload of 1G SFP modules for next to nothing, htey really are super cheap
01:45 PM polprog: I want to see if they will send just any digital signal you feed them or do they need actual ethernet frames
01:45 PM polprog: i hope the optical ones dont need any magick
02:35 PM rue_mohr: so, posting the storage drawers on twitter went crazy...
03:56 PM rue_shop3: hey wait
03:56 PM rue_shop3: an inductor has an impedence at a freqency
04:00 PM rue_shop3: if I know I was running 21.6khz at 3V across 280uH
04:01 PM rue_shop3: 38 ohms
04:02 PM rue_shop3: 78mA
04:02 PM rue_shop3: sounds like the right ballpark
04:54 PM aandrew: polprog: IIRC they are "dumb"; the SFP only does voltage<-->optical and much like the cheap 433MHz radios, you must ensure your signal has an average 0V level
04:55 PM aandrew: er sorry, the avg 0V, I mean it has no long run of zeros or 1s
04:55 PM polprog: Ah, so like the AFBR type transceivers
04:55 PM polprog: yeah
04:55 PM polprog: for mine it turned out to be just below 10kHz, they would emit noise as the AGC goes haywire
04:56 PM polprog: they would start emitting noise on the low transitions of the square
05:36 PM rue_shop3: :)
05:38 PM polprog: i just solved problem 1 of the project for uni
06:13 PM rue_mohr: is it optical?
06:15 PM polprog: no, not even remotely related
06:15 PM polprog: it's gravimetry
06:16 PM polprog: i have data for calcium oxalate, had to plot it
06:16 PM polprog: and then figure out what is going on
06:16 PM polprog: https://0x0.st/-n_v.png
06:16 PM polprog: the blue trace is the relative mass %
06:16 PM polprog: red trace is a temp difference between the reference and the sample
06:18 PM polprog: is that a clapp oscillator you are playing with?
06:28 PM rue_mohr: not really sure
06:29 PM rue_mohr: I'm getting lazy about trying to identify them now
06:29 PM rue_mohr: I'm impressed a 1.5V circuit can genrate a 9V peak signal tho
07:21 PM rue_mohr: so, the royer I made
07:22 PM rue_mohr: according to an LC resonance calculator, the freq is at 50% of what it should be
07:23 PM rue_mohr: I have 140uH, and 0.1uF
07:26 PM rue_mohr: why is there a 200% discrpency
08:14 PM Tom_L: it's all in the math
08:15 PM rue_mohr: mhm
08:15 PM Tom_L: were they jealous of your storage bins?
08:53 PM rue_mohr: https://twitter.com/RueNahcMohr/status/1454150245474979841
08:53 PM rue_mohr: for me even 100 likes on anything is insane
09:11 PM rue_mohr: I wonder if the scope screwed up and measured the freqency wrong becasue of the split waveshape