Singer certainly had a place in early computing. But was it the same Singer that made sewing machines ?
On Fri, Sep 1, 2023 at 5:02 PM Tony Duell via cctalk <cctalk@classiccmp.org> wrote: > On Fri, Sep 1, 2023 at 4:51 PM dwight via cctalk <cctalk@classiccmp.org> > wrote: > > > > My first computer was a Poly-88. I had no monitor and no keyboard. > > I read and understood the instructions about finding a TV that used a > transformer power supply. Many newer TV's of that day were not using a > transformer for the main supply. I went to several secondhand stores and > found one that would work. > > > The original TRS-80 model 1 monitor was based on a live-chassis (hot > chassis?) RCA TV set. The USA version had an optoisolator circuit on > the video input, the LED driver circuit was powered from the +5V line > in the computer (hence the +5V on one pin of the video DIN socket). As > the TV was designed for 115V mains only, the European version has a > step-down transformer on the AC input. They used an isolating > transformer, meaning there was no need to isolate the video input in > the European models. > > Philips made a viewdata termal set where the colour monitor was a > modified KT3 television. The power supply in that starts by bridge > rectifying the mains input, meaning the chassis is dangerously live no > matter which way round the mains is connected. The solution to that > was a 240V 300mA (or so) secondary winding on the mains transformer in > the the viewdate terminal unit. This provided an isolated AC supply to > the monitor, so the chassis of the latter could be earthed. > > > > > > > The keyboard was from a surplus Singer data entry machine ( I thought > they only made sewing machines ). > > Didn't Singer own Friden (or at least the name) at one point? I am > sure I've seen calculators batched 'Singer Friden'). And I have a > telecoms test tone genrator that's badged 'Singer' (I assume the same > company) > > -tony >
