On 5 Mar 2004 11:57:16 -0800, (Paul Probus)
wrote:

I have printed off the pdf version of the treadmill motor controller
schematic at the dropbox retired files. As I was looking it over, I
saw that there are some components that aren't labeled as to what
values they should be. For example, R2 and R4 are not labeled what
their resistance values should be. In addition, and I will admit that
I am a complete novice to electronics, I have no idea what L1 is
supposed to represent and there are no values for its size, so I
cannot even make a guess. I am hoping that those who developed the
schematic are still here.

I'm still here but I'm pretty far from a expert compared to most of
this group. I just reverse engineered the schematic from the board.

As for the values of R2 and R4 they should be on the schematic. At
least they're on the copy that I've got in front of me right now
(you're lucky that I just cleaned up my office and happened to find my
copy a couple of days ago). According to this one R2 is 4K and R4 is
4.74K.

L1 is a torrodial choke and I've not got any clue what it's rated
at. It is one of several components on the board that would be
difficult to source but could probably be worked around by somebody
with more electronics engineering experience than I have.

Keep in mind that there's a resister not shown on the schematic and
not obvious when looking at the board. It's in the form of one of the
traces on the board itself. It snakes around to make for a low value
high capacity resistor in the power portion of the circuit.



While I do have interest in using the controller as-is (if I can get
the values needed) I am also interested in what it would take to
modify the controller for use to control universal motors because I
have need for controlling the speed of a large router, since the
TDA1085C controller IC was designed primarily for universal motors
according to Motorola's literature that I printed off.


The big problem you'll have is that this controller needs a
tachometer on the motor to function properly. That might be hard to
add to a router.

The fact is that I'm not to one who came up with any of the
modifications to the board. I just had the time to make up the
schematic by tracing the board (wish I had that kind of free time now
days). I then posted it and let others do the figuring on how to
modify it.

Wayne Cook
Shamrock, TX