#garfield Logs

Jan 31 2023

01:51 AM ruenahcmohr: its hard to get down to 9600Hz with an LC oscillator on a breadboard
10:06 AM polprog_: ouch, i guess discord needs js to work
10:06 AM polprog_: ruenahcmohr: good job!
10:07 AM polprog_: So that time i made two scanned pages of bh curve math
10:07 AM polprog_: its not wrong but its not right either
10:07 AM polprog_: i rewrote it today and I did some experiments
10:08 AM polprog_: >_< projects projects projects, now i need to build a curve tracer with a switchable integrator
10:08 AM polprog_: https://polprog.net/rozne1/ircjunk/bhtracer.pdf
10:08 AM polprog_: i wrote this in tex so i can do latex2html when its ready
10:08 AM polprog_: i have to add pictures, the plain curve tracer paths look interesting
10:09 AM polprog_: You get a parallelogram (due to 10R shunt resistor) but when the core saturares you get two bulges on its sides
10:09 AM polprog_: I will download the pictures from the camera later today
10:09 AM polprog_: It is not as conveinient as the BH curve but its's a dflux/dtime - H curve
10:10 AM polprog_: which also shows the core saturating and you can also measure it
10:10 AM polprog_: it as in the saturation current
10:10 AM polprog_: I have to add scope traces there
10:21 AM ruenahcmohr: if you start from a high freq and slowly bring it down you can watch it form on the scope and see hitting system limits
10:25 AM polprog_: at high freq the coil impedance kicks in and the curve becomes more of an egg
10:26 AM polprog_: more of a phase shift rather than impedance
10:26 AM polprog_: I was testing with sawtooth wave at 3-30 kHz
10:26 AM polprog_: or even as low as 300Hz
10:26 AM polprog_: that is reasonably good
10:26 AM polprog_: You will see when i include the pictures
10:52 AM ruenahcmohr: ah square wave drive
10:52 AM ruenahcmohr: I was watching it when doing the power converter inductors
10:53 AM ruenahcmohr: hmm
10:53 AM ruenahcmohr: I was really impressed with the math comming out right for the oscillator predictions
10:55 AM polprog_: no, saw wave drive
11:09 AM ruenahcmohr: I think I did a little program for working out the frequency based on a test oscillator
11:10 AM ruenahcmohr: not sure how I set the saturaton current level tho
11:10 AM ruenahcmohr: nobody was there to see it with me
11:31 AM Tom_L: so does that mean it didn't happen?
12:20 PM polprog_: ruenahcmohr, if you refresh that pdf i added some drawings
12:20 PM polprog_: You can see on the 3 curves how the saturation current differs
04:00 PM polprog_: back to self clcking stuff i realized that the MC14500 1-bit CPU is very close to what we do
04:03 PM polprog_: i got it in one of the databooks that I scored
04:03 PM polprog_: https://cdn.discordapp.com/attachments/739849787238776855/1069592212842758175/IMG_20230130_131041.jpg
04:03 PM polprog_: The CMOS Logic one is all about motorola's 4000 series
04:04 PM polprog_: The Communications Devices is also useful, synthesizers PLLs mixers you name it
06:08 PM ruenahcmohr: nice book set!
06:08 PM ruenahcmohr: you know what I just realized too, is that the FSM could - turn the oscillator off -!!!
06:09 PM ruenahcmohr: I think I can optimize that circuit (io count)
08:57 PM aandrew: I had a few of these books
08:57 PM aandrew: the 2181 one for sure, along with the comms and 4000 series