The Boards

The Velleman K8055 ( or Velleman VM110 or Jaycar KV3600 )

http://apogeekits.com/usb_interface.htm

http://store.qkits.com/moreinfo.cfm/K8055

Not really anything to say here yet, other than build the thing (if it is a kit) and test it with the supplied testing program.

And the other board …

Ocean Controls kit No KT 5198

http://www.oceancontrols.com.au:80/motor_controller/dc_motor_controllers.htm (Look for KT5198)

http://store.qkits.com/moreinfo.cfm/KT-5198A

Straight out the “box” these kits are complete and reasonably well documented, although I have heard of some units being supplied with out the documentation.

If you haven’t got a booklet, you can download it here ….

http://www.oceancontrols.com.au/motor_controller/KT-5198%20Dual%20Bidirectional%20DC%20Manual.pdf (Copywrite to the respective owner)

The very early units never had PWM frequency control, so if you think you think you will need control over the PWM frequency, then you can get a later IC to replace the one supplied for about $8 from the supplier you bought the board from. Other than that, the boards I have, worked perfectly ,,, one a kit,, the other a made up unit. Simply speaking, if changing the PWM in my program doesn’t change the performance of the motor, you may have the earlier IC,, but if it performs OK with your setup,, why worry ???

Beefing up the tracks ..

I want to draw about (peak, short time) about 15 amps at 24 volts so I beefed up the tracks where required on the board ….

(Sorry about the fuzzy picture, its the only one I’ve got, but you will get the idea )…

There is another way, and that is to go directly onto the heat sink tabs, but I chose not to do it that way as it would increase the risk of physical damage due to heavy wires going onto the mosfets or their heat sinks.

Cooling and fan etc.

The cooling of the mosfet’s are a must with the current I will be using so I done a mod to help in this department.

NOTE NOTE NOTE !!!!!! The only heat sink tabs that can be joined together electrically are the ones facing one another, back to back.

NEVER, NEVER join all the tabs together in a common heat sink or electrically join any mosfet to any other mosfet, other than the one’s backing on to

one another ,,, if you do, then you will blow it up !!!!

The cooling fin’s are aluminum strip about 3mm thick and bent to suit.

I used heat sink compound just because I had it.

Be careful where you mount this as you cannot have any of the 4 heat sinks touching one another or any earth potential framing.

Time will tell if this is sufficient. (I’m still using the dual wiper motors but building these for industrial type motors)

Heat sink’s 3 and 5 are cut short to allow access to the screw terminals for the motor. (Down thru the fan)

Pictures tell it all….

Then I added the 80mm fan …..

The fan is blowing down onto the heat sinks.

The fan needs to be made of plastic so not to short out different heat sinks.

And then I mounted them both on a board using plastic stand-offs.

Underneath the board is a USB to serial adaptor for the KT5198, so all the connections are USB.

Not related, but a picture of how I made the platform position sensing pots. There are mounted on the wheel rim and coupled to the moving platform via a short length of curtain wire. They are 100Kohm linear.

Progress report. 31-10-07

I am just back from a 2 month holiday in the Aussie outback, but prior to going, the above worked flawlessly for a test run of about 2 hours before Liz grabbed my ear and ripped me out of the thing. (Geeeeze !!!!) (Although, I do have some minor software problems to sort out)

Dated 31-10-07