15-11-2013, 01:17 AM
The circuit Lawrence has described has given me an idea that will help sort out the final components that need to be fitted.
The 5k pot will be used to control the speed however the resistance value across the track terminals needs to be between 2k and 3k. Make up a parallel resistor using one of the 10k pots by setting it with a multimeter on ohms range and start with 5k. Cover the shaft and don't adjust it while connecting it up to the 5k pot and don't connect the other end of the track to anything. Set the other 10k pot to 8k and cover the shaft and don't adjust it again while connecting it up and do not connect the other terminal. Make sure you NEVER power it up with both of the 10k pots set to minimum resistance as it could blow a soldered in fuse in the controller and will cause tears
Finally look up a pot with a value as close to 2k as you can get and set the pot in parallel with the 5k pot to get the same value with a meter across the pair of pots to as close as you can to the value of the one you choose to order.
With the pot that is set to 8k and with the speed pot set to maximum set the maximum speed you want carefully with the machine running using this 10k pot but do not turn it all the way in the higher speed direction direction. You can adjust the speed pot to see how the span changes and this will tell us how close you are getting to to the final fixed resistor you will need to order and fit to complete the job along with the correct 2k pot.
The 5k pot will be used to control the speed however the resistance value across the track terminals needs to be between 2k and 3k. Make up a parallel resistor using one of the 10k pots by setting it with a multimeter on ohms range and start with 5k. Cover the shaft and don't adjust it while connecting it up to the 5k pot and don't connect the other end of the track to anything. Set the other 10k pot to 8k and cover the shaft and don't adjust it again while connecting it up and do not connect the other terminal. Make sure you NEVER power it up with both of the 10k pots set to minimum resistance as it could blow a soldered in fuse in the controller and will cause tears
Finally look up a pot with a value as close to 2k as you can get and set the pot in parallel with the 5k pot to get the same value with a meter across the pair of pots to as close as you can to the value of the one you choose to order.
With the pot that is set to 8k and with the speed pot set to maximum set the maximum speed you want carefully with the machine running using this 10k pot but do not turn it all the way in the higher speed direction direction. You can adjust the speed pot to see how the span changes and this will tell us how close you are getting to to the final fixed resistor you will need to order and fit to complete the job along with the correct 2k pot.
