Permanent Magnet DC (PMDC) Motor Controller

[adamq]

adamq submitted a new Showcase Item:

Permanent Magnet DC (PMDC) Motor Controller

I assembled a PMDC (permanent magnet DC) Motor Controller for use with my variable speed mini lathe.

Forum member "Minder" was extremely helpful with this. Although it's a simple circuit, it can still be confusing for those of us who aren't very experienced with building electronics.

The motor is a 110 VDC (Volt DC) permanent magnet motor, and rated to 250 watts. This should work for any 110-volt DC motor, however, if you adjust the TRIAC and Rectifier to the appropriate amperage.

The original controller is about USD$150 to replace and comes with overload protection, but you can put this controller together for about $15 in a pinch.

Sometimes poverty, not necessity, is the mother of invention

You will need:
- TRIAC (I used Q4008L4 [8-amps 400-volts] but you can use whatever can handle your motor's power)
- DIAC (I used NTE6408 but again, others will work)
- Resistors (3.3k ohm resistor, 15k ohm resistor, 100 ohm resistor)
- Potentiometer (Pot) 250k ohm
- Capacitors (I used three 0.15uf 200-volt capacitors... schematic calls for 0.1uf)
- Bridge rectifier (I used KBPC806 [8-amp 600-volt] but any appropriately sized rectifier will work)

Schematic:
View attachment 31715

What it looks like wired up:
View attachment 31716

Lines showing the connections on the underside of the board:
View attachment 31717

Read more about this showcase item here...

 

[Bluejets]

There exists mains supply dangers in this arrangement as shown that others should be aware of.

 

[Minder]

Although all KB and T.M. DC motor controllers used in this application by many for spindle control etc, also do not offer galvanic isolation.
As is this one that is practically the same as the OP's.
http://www.harborfreight.com/router-speed-control-43060.html
M.

 

[Allen]

This looks like a very useful circuit for me. I put DC motors on my machine tools, up to 1.5 HP @ 90 VDC. I looked a some software to make a custom PCB and was overwhelmed by the complexity of generating it. So, is there an easier way to make a clean looking board with terminals and mounting holes?

 

[Minder]

For one-off's I use Stripboard Prototyping Boards
Halfway down the page.
Use a 1/8th drill to open a trace, the holes can be opened up to accommodate terminal strip etc.
Use a Box cutter knife to run down between each strip to check for shorted strips that may occur.
There is also strip board software out there to assist in layout etc.
M.