#garfield Logs

May 02 2022

12:48 AM rue_mohr: took me a while, but I found an LM317 that outputs a bit low, to do the 1.2V supply for the core voltage of the fpga I'm playing with
12:57 AM rue_mohr: and I need to think up an oscillator
12:57 AM rue_mohr: I'm pondering using the device itself as the transformer with the feedback and everything
12:57 AM rue_mohr: but its only 1 winding right now, I need a center tap
04:56 AM Tom_L: .
08:42 AM rue_bed2: ugh
12:21 PM polprog: why dont you use a regular 4 pin oscillator
02:40 PM polprog: https://0x0.st/oA4k.jpeg
02:40 PM polprog: i guess ill have to find (or build) an amplifier with 330ohm Zout
03:42 PM polprog: and 100V RMS output
03:42 PM polprog: sounds fun
07:10 PM rue_mohr: ?
07:10 PM rue_mohr: no, for the inductance eater
07:11 PM rue_mohr: polprog, "70V" PA amplifiers are common
07:11 PM polprog: I just bought a car radio kit
07:11 PM polprog: Gonna play with that too
07:12 PM polprog: I never seen a PA amplifier
07:12 PM polprog: Plus id like to design my own, ill ask a friend who does analog for help
07:21 PM polprog: https://fccid.io/2ABQZ-JSD/User-Manual/15-JSD-520-UserMan-3972189.pdf
07:21 PM polprog: 4x60W for less than <$10
07:22 PM polprog: with USB, SD card and aux in :)
07:22 PM rue_mohr: just 8R into a transformer
07:22 PM polprog: and bluetooth!
07:23 PM polprog: ill have to make one
07:25 PM polprog: or find one, for 100V
07:25 PM polprog: perhaps i could use an existing mains transformer, use the primary 110V winding for the speaker
07:25 PM rue_mohr: I dont have a source of the transformers et
07:25 PM rue_mohr: yet
07:27 PM polprog: need to match 330 ohms to 4 or 8 ohms
07:28 PM polprog: id need a 110V->2.66V transformer...
07:28 PM polprog: nope
07:29 PM polprog: or find some clever way to use a common transformer to get a 82:1 or 40:1 ratio
07:30 PM polprog: 220 to 6V looks very feasible, thats 5.5:1 ratio
07:30 PM polprog: wait no, what am i calculating
07:31 PM polprog: 220 to 5.5V is 40:1 ratio. close
07:32 PM polprog: if i used a 220V->6V i would match 330ohm speaker to a 9 ohm amplifier
07:32 PM rue_mohr: you dont ahve to be exact
07:32 PM polprog: thats a reflection coefficient of about 5% id say its bang on
07:32 PM rue_mohr: they usually have multiple taps for different volume levels
07:32 PM polprog: its not microwave engineering :D
07:33 PM polprog: https://0x0.st/oA4k.jpeg this is the speaker
07:34 PM rue_mohr: oh wait
07:34 PM rue_mohr: its worth mentioning
07:34 PM rue_mohr: see the volume _SWITCH_
07:34 PM polprog: hm?
07:34 PM rue_mohr: yea, its selecting different taps on the transfomer _THATS IN THE SPEAKER TO CONVERT IT TO 8 OHMS_
07:34 PM rue_mohr: ;)
07:34 PM polprog: wait so the speaker is already 8 ohms?
07:35 PM polprog: no i fet it
07:35 PM polprog: get*
07:35 PM rue_mohr: yea, what you have there is the backside of its transforer
07:35 PM polprog: the actual driver is 8 ohms
07:35 PM polprog: ahhh
07:35 PM rue_mohr: yea
07:35 PM rue_mohr: sorry that kinda slipped my mind
07:35 PM polprog: So the switch here selects the output power and the input impedance of the speaker
07:35 PM rue_mohr: yes
07:36 PM rue_mohr: "with trans"
07:36 PM polprog: ok so for my 8 ohm amplifier id use a 220->6V transformer as above and set the switch to "6"
07:36 PM rue_mohr: trans = transformer
07:36 PM polprog: yes
07:36 PM rue_mohr: no just open it and bypass all that junk, go right to the 8 ohm driver
07:37 PM polprog: oh
07:37 PM rue_mohr: keep it tho, it could be handy later
07:37 PM polprog: i guess that works too
07:37 PM polprog: ill jump it then
07:38 PM rue_mohr: some models dont have the transformer, their just driect to the 8 ohm driver
07:38 PM polprog: yeah i guess this is why it weighs 1.7kg :-D
07:38 PM rue_mohr: :)
07:39 PM polprog: thanks rue!
07:41 PM Tom_L: .
07:41 PM rue_mohr: its not 2am tom...
07:41 PM polprog: its 2am here
07:41 PM polprog: so im going to sleep
07:41 PM rue_mohr: oh
07:41 PM * polprog waves to Tom_L
07:41 PM rue_mohr: ok
07:41 PM Tom_L: buy
07:41 PM Tom_L: !
07:41 PM Tom_L: bye!
07:42 PM polprog: we can never catch each other
07:42 PM polprog: night! :)
07:42 PM Tom_L: i had a nap
07:42 PM rue_mohr: I need to make cages to protect plants
07:42 PM rue_mohr: and I'm falling asleep
07:42 PM Tom_L: chicken wire?
07:42 PM rue_mohr: yes
07:43 PM rue_mohr: well, stucko wire
07:43 PM Tom_L: concrete reinforcing wire?
07:43 PM rue_mohr: more ridgid
07:43 PM rue_mohr: 2" squares
07:43 PM rue_mohr: deer cant quite fit thru
07:43 PM Tom_L: i used 2 x 4 wire
07:43 PM Tom_L: and cut parts out at the bottom so i could reach in and pick tomatoes
07:43 PM rue_mohr: mmm
07:44 PM Tom_L: cucumbers too
07:44 PM Tom_L: they do better if you cage them
07:44 PM Tom_L: i had >200 one year in 6 mounds
07:46 PM Tom_L: you gotta file the wire down though or you end up lookin like a suicide patient
07:47 PM Tom_L: also for storage i made them different sizes so they would fit inside each other
07:47 PM Tom_L: 4 sizes
07:49 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/temp/house/house.jpg
07:49 PM Tom_L: back row there
07:49 PM Tom_L: used concrete reinforcing rod to hold them up
07:50 PM Tom_L: made 12" extensions on the sprinkler so as it grew i could make them taller
07:51 PM Tom_L: wire cage row is in the middle
07:51 PM Tom_L: barely see it
10:33 PM rue_mohr: I dozed off
10:33 PM rue_mohr: damn
10:38 PM Tom_L: https://imgur.com/gallery/qycDcBz
10:39 PM rue_mohr: ugh,t hat doesn't work
10:39 PM rue_mohr: has to be a link to the image
10:40 PM Tom_L: https://imgur.com/ANpJo9A
10:40 PM Tom_L: ?
10:42 PM rue_mohr: no, has to end in .jpg or whatever
10:43 PM rue_mohr: they specifically hide it if they see my browser
10:45 PM Tom_L: https://i.imgur.com/ANpJo9A.jpeg
10:49 PM rue_mohr: hahah
10:50 PM rue_mohr: after weeks.. hahaha