Re: Cordless screwdriver innards?

From: Terry Pinnell (terrypinDELETE_at_THESEdial.pipex.com)
Date: 07/06/04 

Date: Tue, 06 Jul 2004 08:56:04 +0100

"John Jardine" <john@jjdesigns.fsnet.co.uk> wrote:

>I've scrapped 3 of them. The leccy bits are all within the trigger mech.
>Speed control via a tiny linear pot moulded with the trigger. I found the PM
>motors are OK but the electronics are magnificently designed and constructed
>to do just the job in hand and very awkward to cannabalise for other uses.
>Good luck with the curtain openers :-).

>Tried it once with a windscreen wiper motor. This apparently simple project
>to do a useful simple job, escalated over a 2 week period into a screaming
>nightmare of electronic controls, timers, limit switches, wires, cords,
>pulleys and mechanical hardware. The dynamics never 'felt' right and the
>eventual size weight and complexity of this monster caused it (thankfully!)
>to fall off the wall. A version #2 a couple of years later. worked but
>wasn't really worth the effort.
>Learnt at that point that some things are better off being industrially
>manufactured.

Thanks, very helpful. All I'm hoping for is to be able to (a) open it
up without bits flying off in all directions, and (b) solder thin
wires to the F/off/B switch contacts and still be able to close the
thing up again.

Alternatively, I could dust off my existing unit, based like yours on
an old windscreen wiper motor. It briefly served as a lounge curtain
opener (until my first wife objected on aesthetic grounds - a
reasonable complaint; it was an ugly accessory <g>). But I then
adapted it as a window opener/closer, where it worked well for some
years. It let me keep the window closed while dozing off reading in
bed, without light-attracted moths and other bugs getting in, and
avoided having to then get up (and wake up) to open window for fresh
air overnight.

Here's a photo taken during developement
http://www.terrypin.dial.pipex.com/Images/WindowOpener1.jpg
and here's the circuit
http://www.terrypin.dial.pipex.com/Images/AutoMotorExtremes.gif 

-- 
Terry Pinnell
Hobbyist, West Sussex, UK

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