thanks Bert, I found another document (M100SIG) that suggested the components to add were a 10 ohm resistor and a silicon diode. Interesting. All hacks place a circuit between the orange and red leads.
Option 1: 47 ohm - works, but does not prevent reverse conduction from batteries to an unplugged wallwart option 2: 10 ohms + silicon diode: - protects from reverse current, but drops the voltage for charging option 3: 10 ohms + schottky diode - also protects , maybe a little less voltage drop? On Mon, Nov 23, 2020 at 4:04 PM Bert Put <[email protected]> wrote: > Hi Steve, > > Email from 2010... :-) > > Hope this helps. > > Cheers, Bert > > > > From: Frederick Whitaker <[email protected]> > To: [email protected] > Date: Sun, 03 Jan 2010 08:15:53 -0500 > Subject: Re: Recharging Circuit! > > Thank you for finding that error, I didn't see it when I did the proof > reading. Anyone who wants to keep that information can make that change, > or they can use the change I am adding to this email. > > Fred Whitaker > > IZ2eib wrote: > > --- Dom 3/1/10, Frederick Whitaker <[email protected]> ha scritto: > > > > > >> Da: Frederick Whitaker <[email protected]> > >> Oggetto: Re: Recharging Circuit! > >> A: [email protected] > >> Data: Domenica 3 gennaio 2010, 02:56 > >> > > > > > >> I have no idea why it calls for 4 > >> watts. > >> > >> Fred Whitaker > >> > > > > Hi Fred and all member list. > > Resistor is 1/4W (0,25W), no 4W: 4W is a typo. > > Please look at http://www.club100.org/library/libp100.html, > > there are all Portable 100 Magazines, download Vol. 3 No. 7 Mar 1986 > and read on page 44: you can read "The resistor you need for > self-charging is a 47 ohm, 1/4 watt resistor which you can find at any > electronics or TV repair store". > > I believe that the error is due to conversion of the original > document, nothing serious. > > Since 1983, and as usual, club100 is the bible of Tandy 100's family > laptops thanks to Rick Hanson!!! > > > > Regards, > > > > Fabio. > > > > > > > > > > > > > > A Simple Self-Charger for the 100 > > BY JOHN L. MENKE AND SUSAN M. MENKE > > > > The Model 100 is easy to use, powerful and lightweight. It also eats > > batteries. > > > > If you're tired of hand-feeding it every few hours, you can modify its > > dietary habits to self-charge. All you need are a resistor, a power > > line adapter (current retail cost $5.95) and a quartet of rechargeable > > batteries. > > > > After you've owned your machine for 90 days, its warranty expires and > > this modification won't affect it. If your warranty is still in force, > > we point out that Radio Shack does not recommend what we're about to > > describe. However, we've had no problems with our two machines over > > several years of use. > > > > RECHARGEABLE BATTERIES Rechargeable nickel-cadmium (nicad) batteries > > have a nominal voltage of 1.2 volts (V). This remains virtually > > constant as the cell discharges, then drops quickly to near zero. Four > > such batteries give the Model 100 a combined voltage of 4.8 volts, > > which is lower than the recommended 6.0V. The 100 will shut itself off > > if voltage drops slightly below 4.8V. In spite of this relatively > > narrow voltage band, we have never experienced problems from low power > > shutdown. > > > > We have tried several brands of nicads. All give about 8-10 hours of > > use when fully Charged. Makers recommend occasionally letting the > > cells run all the way down before recharging. Our experience is that > > repeated partial discharge (or extensive use of trickle charging) will > > reduce charge life to 4-5 hours. One or two cycles of full > > discharge/recharge restores the 8-10 hour useful life. > > > > We have used the same nicads for hundreds of cycles over two years > > without evident degradation. Aside from the relatively limited life of > > each recharge, the only noticeable effect is a very short warning time > > after the lowbattery light comes on, before the 100 shuts itself off. > > > > Different brands of nicads have slightly different dimensions. The > > positive tips of Radio Shack nicads are somewhat shorter than those of > > other makers such as Lynacharge, so use of the Radio Shack cell can > > lead to poor positive contact and intermittent operation. If you > > experience this, the best solution is to switch to a different brand > > of nicad. However, it's possible to use needlenose pliers and > > partially uncoil the 100's positive spring terminals for better contact. > > > > HOW TO ADD THE SELF CHARGER RESISTOR > > > > You probably wonder, as we do, why all portable computers don't have > > built in rechargeable power supplies. Radio Shack has been > > consistently guilty of this fault, and even compounds it with new > > battery-powered products that lack automatic shutoff. > > > > However, if you have ten minutes and twenty cents, you can wire in a > > resistor (without soldering) that will recharge your IOU overnight > > from a power line adapter. > > > > We repeat: This change may invalidate your 90-day warranty if still in > > effect.but there is virtually no risk from adding a resistor, nor will > > it make troubleshooting difficult if your machine should ever need > > repair. Simply removing the resistor before sending the 100 for > > service will avoid any issue being raised. . > > > > The resistor you need for self-charging is a 47 ohm, 1/4 watt resistor > > which you can find at any electronics or TV repair store. A resistor > > twenty percent above or below those values will still work. > > > > On 11/23/20 2:54 PM, Stephen Adolph wrote: > > Wondering if anyone recalls or can point to the small modification > > needed to be able to use NiMH or NiCd batts in the M100, and enable > > charging? > > Seems to me there was a nice little change you could make. > > thx > > Steve >
