upgrading my minilathe motor control

[hobby]

I'm upgrading my motor controle for my 7 x 10 minilathe, I'm converting it from my original class A amplifier analog design with current feedback, to my version of PWM with current feedback for torque control.

This is a very quick demo. of my version of design using all discrete transistors, for my PWM with torque feedback circuit, that I am going to use for my mini lathe.

https://youtu.be/a9aX4NlnSmM

I still need to design the oscillator circuit for it, but the main design of getting a pulse width modulation, and feedback for torque control was the aim for this experiment.



Have fun in the shop.

 

[bmac2]

Hi Hobby
It looks like we’re heading to the same place just taking different routes. I’ve been having problems with the controller in my mini-mill. I was thinking of repairing it but the boards in my mill look very cheaply made.

What I’m using is the PWM output on an Arduino. Sorry for the fuzzy picture, I haven’t found a way to export from my cad system that’s useful.:shrug:

View attachment Mini-Mill.pdf

 

[hobby]

I know what you mean, those boards seem to need repaired or replaced quite often, looks like you got a good solid controler drawn up, please let us know how well it works for you.

 

[bmac2]

Thanks Hobby
I have had it working on a breadboard. When I got my mill (used) it came with a second motor and you can tell from the video why it was replaced. This past weekend I got the “if something bad happens” circuit working the way I want it so now I’m scraping 20 years of rust off the part of my brain that remembers how to layout a PCB.
One thing I don’t like about the original control circuit is that it takes the mains voltage, runs it through a bridge and straight to the MOSFETs. This has the potential for a failure on a biblical level so I want to put in an isolation transformer.
In the video the pots wired backwards and watch your volume . . . . that motor is just nasty!

[ame]https://www.youtube.com/watch?v=VB2Fa4JetvU&feature=youtu.be[/ame]

 

[hobby]

Very nice, it has nice linear control,
Your breadboard looks very neat and orderly.
PC board layout can be fun, it will come back to you as you get back into it.

I was going to make a PC board for my new controller, but instead I opted this time to build my entire circuit on a breadboard module, that way I can always easily troubleshoot and replace components or redesign the circuit at any time I need to.