isaac-b@tahoe.unr.edu (Benjamin Isaac) (02/23/90)
I have had a lot of problems locating a decent schematic for a speed controler
for a cordless drill.
The type of schematics I am looking for is one that:
1. DOESN'T use a transitor/resistor design (i.e. heat/excessive drain).
2. doesnt require extremely hard to find components.
3. can handle around 1amp at 6volts.
4. will hopefully have some torque at lower speeds.
I would appreciate any help through e-mail or through this newsgroup.
net: isaac-b@tahoe.unr.edu
rdi@cci632.UUCP (Rick Inzero) (02/23/90)
In article <3609@tahoe.unr.edu> isaac-b@tahoe.unr.edu (Benjamin Isaac) writes: >I have had a lot of problems locating a decent schematic for a speed controler >for a cordless drill. > >The type of schematics I am looking for is one that: > > 1. DOESN'T use a transitor/resistor design (i.e. heat/excessive drain). > 2. doesnt require extremely hard to find components. > 3. can handle around 1amp at 6volts. > 4. will hopefully have some torque at lower speeds. > >I would appreciate any help through e-mail or through this newsgroup. > >net: isaac-b@tahoe.unr.edu > If anyone has a good, tried-and-true circuit for this, I'd be interested in seeing it posted too! I've found a "Speed Control for Power Tools" schematic in the Feb. 1967 Popular Science (plus a correction on p. 10 of Apr 1967), but is uses resistors and a mechanical contact set up that would be difficult to make from scratch. Hey, at least it matches the age of my electric drill!! --- Rick Inzero rochester!cci632!rdi Computer Consoles Inc. (CCI) uunet!ccicpg!cci632!rdi Rochester, NY uunet!rlgvax!cci632!rdi "Your grandmother never, ever called me stupid. She always called me 'pinhead'." -Jimmy Stewart in 1988 Campbells Soup commercial.
grege@gold.GVG.TEK.COM (Gregory Ebert) (02/24/90)
In article <3609@tahoe.unr.edu> isaac-b@tahoe.unr.edu (Benjamin Isaac) writes: >I have had a lot of problems locating a decent schematic for a speed controler >for a cordless drill. > >The type of schematics I am looking for is one that: > > 1. DOESN'T use a transitor/resistor design (i.e. heat/excessive drain). > 2. doesnt require extremely hard to find components. > 3. can handle around 1amp at 6volts. > 4. will hopefully have some torque at lower speeds. > Easy. Use a tapped-voltage power source. If you have 4 batteries rated 1.5 volts apiece, you get 4 possible voltages: (1.5,3,4.5,6). The 1.5 might be useless, but the other 3 should be OK. Some batteries get 'bogged-down' by internal series resistance, so you may want to use 5 cells for 7.5 v (MAX). Be careful you don't overload the batteries. Some reachargeable cells will 'vent-off' at high drain-rates due to excessive heating. This puts yucky corrosive fumes in your equipment :( .