#garfield Logs

Mar 10 2024

01:08 AM rue_mohr: I'm determined to make a better small-camera tilt-and-pan than what I can find online, but I'm failing hard
01:21 AM rifraf: new chip tray and deflector catching most chips https://www.youtube.com/shorts/2YBMQ0zRGhM
01:28 AM rue_mohr: oh I'm an idiot
01:28 AM rue_mohr: joystick!
01:28 AM rue_mohr: does this work?
01:33 AM rifraf: possibly
01:37 AM rue_mohr: https://www.aliexpress.com/item/1005005388580874.html w t f
01:40 AM rue_mohr: ah it reloaded with a proper price
01:41 AM rifraf: looks cheap enough
04:18 AM WormFood: rue_shop2, sorry I didn't see your message earlier. Try this (it's tiny) https://colorcomputerarchive.com/repo/Cassettes/Utilities/All%20RAM%20Mode.zip The zip contains a wave file, plus the raw data contained in the wav file. The header of "55" is to allow the software to sync.
04:19 AM WormFood: So, if you measure the time between two rising pulses, it should take X or Y cycles depending on if it's a zero or one, but if you get a time that is between X and Y, then you're out of sync.
04:26 AM WormFood: If you want something with more data in it, then download this one (only 39k) https://colorcomputerarchive.com/repo/Cassettes/Utilities/Hi-Res%20Screen%20Print%20Utilities%20(Tandy).zip
04:28 AM WormFood: The project is called CasDuino or MaxDuino
06:36 AM rue_mohr: did you get it working yet?
01:21 PM WormFood: I haven't gotten my bench cleared off enough where I can work on it yet.
01:22 PM rue_mohr: mhm
01:22 PM rue_mohr: how much of the used space is incomplete projects?
01:22 PM WormFood: Most of my mess is just due to be lack of organizing abilities.
01:23 PM WormFood: I actually don't have any incomplete projects right now. I have a few vintage computers I'm working on. Just got my ICs the other day, so that's really the only thing I'm in the middle of.
01:24 PM WormFood: And I just realized, I can't find one of the ICs I need for this project. I'm gonna build a zero crossing circuit, to interface the audio to the arduino.
01:40 PM rue_shop2: mhm
01:41 PM rue_shop2: capacitor, resistor divider, optional 74hc14
02:12 PM WormFood: https://colorcomputerarchive.com/repo/Documents/Manuals/Hardware/Color%20Computer%20Technical%20Reference%20Manual%20(Tandy).pdf page 75 on pdf (68 on the page) Look at P5, pin 4, that feeds the zero crossing detector
02:13 PM WormFood: The 10uf cap and resistor divider, that goes off-sheet, is for the audio amplifier. The output of the LM339 feeds an input pin on a PIA
02:15 PM rue_shop2: sure
02:17 PM rue_shop2: yea thats all it is anyhow
02:17 PM rue_shop2: the series cap is just in the tapedeck
02:18 PM WormFood: There are several different computers that use the identical zero crossing circuit.
02:18 PM rue_shop2: yea
02:19 PM rue_shop2: could have saved so many io with a scan-free keyboard decoder too
02:21 PM rue_shop2: I wonder why they used a DAC
02:21 PM WormFood: The "Dragon32" computer, had one slight difference. It has a 470 ohm resistor in series from pin 4(of P5) to the rest of the circuit, and has a pair of diodes on the other side of that 10uf cap,
02:21 PM WormFood: This is more or less the Motorola reference design for the 6809
02:21 PM rue_shop2: must be something to do with the joystick
02:21 PM rue_shop2: oooh yea
02:22 PM WormFood: Yeah
02:22 PM WormFood: 6 bit
02:22 PM rue_shop2: they use the DAC for getting the joystick position to 6 bits
02:22 PM rue_shop2: cute
02:22 PM WormFood: Right
02:22 PM WormFood: 64x64
02:22 PM rue_shop2: heh, I hope they used SAR instead of a ramp
02:23 PM WormFood: There is a high resolution joystick interface. The reprogram one of the button inputs to be an output, and manipulate a circuit to improve the resolution.
02:24 PM WormFood: Tandy used to sell them, back in the day. You plugged your joystick into this box, and the box had 2 cables to plug into the computer. Later, someone modified it, where it could work with just a single cable (but few titles supported either type of high-res joystick interface.)
02:25 PM rue_shop2: so they probably only use 0x00 and 0x3F for the tape write
02:25 PM WormFood: well, of course. it's only 6 bits :P
02:26 PM rue_shop2: but I suspect they didn't use the values in between
02:27 PM rue_shop2: I need a bit more get-up-and-go
02:39 PM WormFood: The DAC is used for recording the cassette data to the tape, and is not used for playback. That's why I'm not interested in that circuit. The AVR can output a signal it will read as cassette data, but it can't input that signal without help.
02:41 PM rue_shop2: yup
03:43 PM rue_shop2: ok getting work done on the reduction pullies for the X on the cnc
03:43 PM rue_shop2: the two seem to be good
05:17 PM rue_mohr: Tom_L,
05:17 PM rue_mohr: pulley
05:17 PM rue_mohr: about 1.5-2" dia
05:17 PM rue_mohr: small V belt
05:17 PM rue_mohr: 10k RPM
05:18 PM rue_mohr: considerations you can think of to make it?
05:18 PM rue_mohr: I'm thinking NOT cast metal
05:25 PM Tom_L: belt won't hold up those rpm
05:26 PM Tom_L: at those rpm balance is a big issue
05:27 PM Tom_L: lathe
05:28 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/new_pulleys/old_pulley2.jpg
05:28 PM Tom_L: i made that one and wasn't that happy with it's performance
05:35 PM rue_mohr: hmm
06:22 PM Tom_L: maybe a different type of belt would be better suited for that
06:23 PM rue_mohr: I'v got a lot invested in this, I'd like to take it to failure
06:26 PM Tom_L: lathe it is then
06:26 PM Tom_L: make sure you don't pinch the belt with the grooves or make them too sloppy
06:26 PM Tom_L: mine were a bit tight i think
06:26 PM rue_mohr: hmm
06:26 PM rue_mohr: the motor is 10k
06:27 PM rue_mohr: there is about 3.5:1 to the first pulley
06:27 PM rue_mohr: then two more 3.5:1
06:29 PM Tom_L: they could all be different depending on the load and speed requirements
06:35 PM rue_mohr: 10k -> ~100:1 = ~1m/s peak jog, with the ~ 10 degrees/ 0.05mm I'm looking for
06:36 PM rue_mohr: twice in one week I'v had people interested in using by big cnc
06:36 PM rue_mohr: one would be into putting the $400 in motors into it too
07:57 PM Tom_L: servos or stepper?
07:57 PM Tom_L: probably servo
07:57 PM rue_mohr: $400 for 3 BIG steppers
07:57 PM rue_mohr: the ones rif was reffering to
07:58 PM Tom_L: missed that
08:01 PM rue_mohr: bit over $100ea
08:02 PM rue_mohr: feedback and built in drivers and all that stuff
08:02 PM Tom_L: nema 34?
08:02 PM rue_mohr: I didn't evaluate them for speed and resolution tho
08:02 PM Tom_L: right closed loop steppers
08:02 PM rue_mohr: dont recall if thats 34 or bigger
08:02 PM Tom_L: big steppers will be slower
08:03 PM rue_mohr: again, without funds, no.
08:03 PM rue_mohr: the brushed motors I'm working on will peak 1HP
08:03 PM rue_mohr: which they dont need to do for long
08:04 PM rue_mohr: I do need to set up the Y drive tho
08:04 PM Tom_L: how does grbl handle dual motor axis?
08:04 PM rue_mohr: looking at using a gearbox with lash, because the Y carriage has heavy gravity influence
08:04 PM rue_mohr: dont want to do that
08:04 PM rue_mohr: but I'd just parallel the step/dir
08:06 PM rue_mohr: how you been latley, irc been quiet
08:06 PM rue_mohr: I'm going stirrcrazy
08:07 PM rue_mohr: +- a few new faces on the internet I'm getting less than ever done
10:15 PM rue_mohr: I cant find a solid piece of aluminum stock to make the pulley from
10:15 PM rue_mohr: 10k I dont want it cast
10:16 PM rue_mohr: I wonder, with the load, if it can get up to that
10:16 PM rue_mohr: maybe I should just make it and run it slow till I get something else
10:16 PM Tom_L: not even plate?
10:19 PM rue_mohr: plate would be hard to mount to the shaft
10:19 PM rue_mohr: I'd like to do this in one part
10:19 PM rue_mohr: use symmetic bolts to lock it on
10:24 PM rue_mohr: interseting, I wanted to show you a picture, but all the high speed motors are now using a collette type mount
10:24 PM rue_mohr: for mounting things to the shaft
10:28 PM rue_mohr: https://ae01.alicdn.com/kf/Ha3f6877eb2504d6791904fe386ac1d380.jpg
10:28 PM rue_mohr: you can kinda see it there,
10:28 PM rue_mohr: to balace the set screw, they use two at 180 degrees