I was going to build the coil winder using a drill powered by a 300W, 0 - 40V variable voltage supply. I built the supply using a variac and large torroid transformer. The supply worked and is nearly indestructable, then I remembered I had some huge stepper motors...
...so I used those instead.
At least I now have another power supply :)
The stepper motor is driven by a microcontroller (ATtiny2313) with coils driven by mosfet's (BUK9840). The speed and direction of rotation is varied using a rotary encoder. The micro spits out information on speed / direction / revolutions on its UART. The UART connects to an LCD.
The motor coils are rated for 3 volts. To trade off some torque for speed the motor coils are driven from a 12V supply via some resistors. These get quite warm in use, the only ones I had with a large enough power dissipation were 25W aluminium resistors, so no trouble there.
I was going to use a shift register to drive the LCD from a couple of pins, but didn't have any. I have lots of ATtiny2313's so I stuck one on a board with the LCD and used the UART to shift data to the display. The LCD microcontroller has a 32 character buffer into which any characters received on the UART are stored. Characters below an ASCII space reset the buffer index to zero.
Very simple, now I've written the code for that it will be useful for other stuff.
To turn the piece of pipe which will be the secondary's former, I made two 'centers' out of the only stuff I had, concrete. I used two plastic funnels for a mold, which also held the aluminium shaft central while the concrete went off.
Here, the bottom funnel is full of concrete and its stuffed into a bucket of sand while it sets.
The finished winder with first coil secondary. The two blue concrete 'centres' are holding the piece of plastic pipe.
This only took about 15 minutes to wind, I was expecting to spend at least an hour on it.
No comments:
Post a Comment