On Sat, 16 May 2009 10:22:45 -0700, Fred Abse <excretatauris@invalid.invalid> wrote:>On Sat, 16 May 2009 09:34:46 -0700, Jim Thompson wrote: > >> Could the first "space" be made long? > >The first space is the start bit from which the sample timing originates. >It's the usual start/stop protocol: One start bit, five NRZ data bits, 1.5 >stop bits. The start bit trips the clutch that starts the reading >mechanism, which samples the position of the selector magnet at fixed >intervals. The mechanism resets after 5 bit intervals and the clutch >disengages. You can regard the idle condition as one long continuous stop >signal, it's actually only 1.5 bit intervals between successive characters >in a string. > >Most machines have an adjustment to set the sampling window relative to >the start so as to get the sample on the flat part of the pulses. > >I once had a teletype as printer for a TRS-80 (remember those?), using the >cassette motor relay for signaling. I think I've still got the Z80 >assembly code somewhere.So make a 120V supply that can supply just the "leak-off", then the "snub" energy won't go to waste and heat. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Stormy on the East Coast today... due to Bush's failed policies.
Re: LTspice question: modelling a solenoid
Started by ●May 7, 2009
Reply by ●May 17, 20092009-05-17
Reply by ●May 18, 20092009-05-18
On Sat, 16 May 2009 09:10:20 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:>On Sat, 16 May 2009 08:43:14 -0700, Fred Abse ><excretatauris@invalid.invalid> wrote: > >>On Tue, 12 May 2009 15:24:51 -0700, Jim Thompson wrote: >> >>> Now at device level (no behavioral).... >>> >>> http://analog-innovations.com/SED/HammerDriver(J.Nagle)2.pdf >> >>There's a problem with this, Jim. Your circuit works fine with a >>continuous pulse train, but teletype isn't like that, it can have long >>periods of no activity (constant Mark signal), then a few characters, then >>more inactivity. The selector magnet must respond to the first drop to >>Space (beginning of start bit) of the first character. >>[snip] So add a weenie supply to keep the capacitor "alive", as shown in... www.analog-innovations.com/SED/HammerDriver_RevD.pdf Since the current requirements are essentially leakage, I'd be tempted to use a capacitor type feed directly from the AC line. I do that often in appliance control chips. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Stormy on the East Coast today... due to Bush's failed policies.
Reply by ●May 19, 20092009-05-19
On Sun, 17 May 2009 03:17:51 -0700, Fred Abse <excretatauris@invalid.invalid> wrote:>On Sat, 16 May 2009 18:35:20 -0700, JosephKK wrote: > >> Punched tapes could reliably achieve this tightness of character >> separation. Manual typists had much more jitter in start to start. =The>> system is truly asynchronous between characters. Intra character =timing>> was created by steady speed electromechanical means. > >Most machines needed either CR-CR-LF or LF-CR-CR as end-of-line, adding =a>delay, to allow the carriage or basket to fully return, otherwise you =got>the first character of the next line printing whilst the carriage was >still flying. > >That's the reason for the still-widespread CNC tape code using LF-CR-CR. >It was designed for ASR33s et al. > >When all the "modern" magnetic and semiconductor media have lost data, >punched paper tape will still be readable, by humans if necessary.And just what, per se, does that have to do with what i said?
Reply by ●May 19, 20092009-05-19
On Mon, 18 May 2009 17:44:49 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote:>On Sat, 16 May 2009 09:10:20 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote: > >>On Sat, 16 May 2009 08:43:14 -0700, Fred Abse >><excretatauris@invalid.invalid> wrote: >> >>>On Tue, 12 May 2009 15:24:51 -0700, Jim Thompson wrote: >>> >>>> Now at device level (no behavioral).... >>>> >>>> http://analog-innovations.com/SED/HammerDriver(J.Nagle)2.pdf >>> >>>There's a problem with this, Jim. Your circuit works fine with a >>>continuous pulse train, but teletype isn't like that, it can have long >>>periods of no activity (constant Mark signal), then a few characters, then >>>more inactivity. The selector magnet must respond to the first drop to >>>Space (beginning of start bit) of the first character. >>> >[snip] > >So add a weenie supply to keep the capacitor "alive", as shown in... > > www.analog-innovations.com/SED/HammerDriver_RevD.pdf > >Since the current requirements are essentially leakage, I'd be tempted >to use a capacitor type feed directly from the AC line. I do that >often in appliance control chips. >Where did the OP of this thread (John Nagle) go to? ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Stormy on the East Coast today... due to Bush's failed policies.
