D
DaveC
- Jan 1, 1970
- 0
My new cordless screwdriver runs on 7.2vdc Li-Ion batteries (pm brush motor).
It's not variable but runs at one speed (2000rpm) which is nice when you need
it, but for many tasks it's way too fast.
I like everything about this tool except the speed. I'd like to add a second
speed, half or maybe slightly slower than half.
Obviously space is at a premium in cordless tools like this, so minimum
component count for this modification is paramount.
I know I can just hang a large resistor off of the battery and a large switch
for routing current through it, but I was hoping for a solid-state solution.
Is there any advantage to using a bipolar or MOSFET or such over the
bog-simple resistor method? (ie, it requires a smaller switch; a transistor
might be easier to mount externally than a resistor to cool it, etc.).
Ideas?
Those who think a PIC can be adapted to this requirement, please be prepared
to show your work. (c:
Thanks,
It's not variable but runs at one speed (2000rpm) which is nice when you need
it, but for many tasks it's way too fast.
I like everything about this tool except the speed. I'd like to add a second
speed, half or maybe slightly slower than half.
Obviously space is at a premium in cordless tools like this, so minimum
component count for this modification is paramount.
I know I can just hang a large resistor off of the battery and a large switch
for routing current through it, but I was hoping for a solid-state solution.
Is there any advantage to using a bipolar or MOSFET or such over the
bog-simple resistor method? (ie, it requires a smaller switch; a transistor
might be easier to mount externally than a resistor to cool it, etc.).
Ideas?
Those who think a PIC can be adapted to this requirement, please be prepared
to show your work. (c:
Thanks,