Today i spent a bunch of time going nowhere trying to configure a raspberry pi 4 with raspberry pi os to act as a wifi to ethernet bridge.
I think I might try to configure one of the "cpu nodes" in my server, running Mint to bridge instead. In theory it should be similar if not exactly the same, but ive had no luck with the pi. I suppose I could try pfsense. Idk, I'll decide when I have patience for that again.
Ok, so I got openwrt "working". The raspberry pi is definitely haunted by the ghosts of a dead installation, but if it gives me Internet from afar, that's fine.
I followed a couple guides to get a bridge setup, but for some reason, the pi wouldn't talk to the router at all. Openwrt says it's connected. The router doesn't list it as a client, and I cant ping anything from the pi. I try a bunch of things to no effect and decide to start over with a fresh image. I use rpi-imager. I power on the pi and connect a thinkpad to try to log in to the web ui like I did before, but it wont connect at all. I try various things for awhile and decide the data must have gotten corrupted the second time I flashed the sd card. I take the sd card, format the whole card, quick, no overwrite, in order to try to make things real clean. I flash openwrt to it for a 3rd time. I power on the pi. I enter the IP for the webui, and it redirects me to the login page for the router . . . like it's a working bridge all properly configured with the wifi password and everything . . . even though I rewrote openwrt to the sd card twice . . .
Im sure there's some logical explanation like openwrt caches some stuff to something on the pi itself or maybe the sd card held some data, cuz I didn't overwrite it, but I think it's more fun to believe
Pi's haunted
Used a little usb oscilloscope for my phone to set my signal generator to as close to 9V peak to peak and 2.5kHz as I could. Now to adjust the first display to match
The trimmer knob is close to one end, but I think I got it all set right.
I hooked up a signal generator, and we can see a sine wave in the first display!
Used a little usb oscilloscope for my phone to set my signal generator to as close to 9V peak to peak and 2.5kHz as I could. Now to adjust the first display to match
The testpoints measure 115VDC and +7.4VDC. I didnt measure the middle cuz it's a little awkward to reach, and I don't want to short anything. 7.4 seems a little too low for me, but I'll keep checking it and see if it changes as the caps get reformed with use
I hooked up a signal generator, and we can see a sine wave in the first display!
Ive never seen a crt running from above/behind before, and wow it looks cool. It feels weird to just see some little green lines floating there
The testpoints measure 115VDC and +7.4VDC. I didnt measure the middle cuz it's a little awkward to reach, and I don't want to short anything. 7.4 seems a little too low for me, but I'll keep checking it and see if it changes as the caps get reformed with use
And we have life! One tube doesn't show a line like the others, but I see a dot appear on it when I turn everything off, so it might just need some adjustment
Ive never seen a crt running from above/behind before, and wow it looks cool. It feels weird to just see some little green lines floating there
Next are the circuits for each individual display. It looks like they use a lot of ceramic caps. Some of the non-ceramic capacitors I might be worried about look similar to one I measured in the high voltage card, and it was dead-nuts on, so I think they're probably fine. There's some orange-drop caps, and on one card, they're blue instead of orange. There's no obvious signs of service or repair, so I think the color change would just indicate a change to a new order of capacitors at the factory. There's some small diodes, which given the age wouldn't surprise me if they need replacement, but they're hard to access, and everything else seems pretty good, so I think I'll plug it in and see what happens.
And we have life! One tube doesn't show a line like the others, but I see a dot appear on it when I turn everything off, so it might just need some adjustment
It has 1 big sprague cap which seems good, and 3 of obscure brands which all measure a little high. 2 of them are only rated for 16V and the other is rated for 200V. This is also in-circuit, so the measurements can rightly be questioned, but I think I'll keep an eye on them and what those 8V testpoints measure
Next are the circuits for each individual display. It looks like they use a lot of ceramic caps. Some of the non-ceramic capacitors I might be worried about look similar to one I measured in the high voltage card, and it was dead-nuts on, so I think they're probably fine. There's some orange-drop caps, and on one card, they're blue instead of orange. There's no obvious signs of service or repair, so I think the color change would just indicate a change to a new order of capacitors at the factory. There's some small diodes, which given the age wouldn't surprise me if they need replacement, but they're hard to access, and everything else seems pretty good, so I think I'll plug it in and see what happens.
And heres the low voltage power card. It is visually similar, so I wont bother with alt text. It has an aluminum plate to dissipate heat from some silicon components, and is also model 1201. It's slot has some pins next to it labelled +120, -8, and +8. They're not connected to anything, so I guess they're test points.
It has 1 big sprague cap which seems good, and 3 of obscure brands which all measure a little high. 2 of them are only rated for 16V and the other is rated for 200V. This is also in-circuit, so the measurements can rightly be questioned, but I think I'll keep an eye on them and what those 8V testpoints measure
Here's the high voltage power card. The capacitors were all at 0.0V, and their in-circuit capacitances were all within spec. Even tho it's been sitting for unknown decades, I think this card is probably safe to power up. The little bar isn't electrically connected to anything. I think it's just to help put the card in the slot.
And heres the low voltage power card. It is visually similar, so I wont bother with alt text. It has an aluminum plate to dissipate heat from some silicon components, and is also model 1201. It's slot has some pins next to it labelled +120, -8, and +8. They're not connected to anything, so I guess they're test points.
TommyTorty10