Reply by Jim Thompson 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.
Reply by JosephKK 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 Jim Thompson 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 Jim Thompson May 17, 20092009-05-17
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.
Reply by Fred Abse May 17, 20092009-05-17
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. -- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)
Reply by JosephKK May 16, 20092009-05-16
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.
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 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.
Reply by Fred Abse May 16, 20092009-05-16
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. -- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)
Reply by Jim Thompson May 16, 20092009-05-16
On Sat, 16 May 2009 09:25:47 -0700, Fred Abse
<excretatauris@invalid.invalid> wrote:

>On Sat, 16 May 2009 09:10:20 -0700, Jim Thompson wrote: > >> If "Mark" is current in the solenoid, it's fine. > >On a neutral (current or no current) system, mark is no current. >Makes idling more economical.
Could the first "space" be made long? ...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 Fred Abse May 16, 20092009-05-16
On Sat, 16 May 2009 09:10:20 -0700, Jim Thompson wrote:

> If "Mark" is current in the solenoid, it's fine.
On a neutral (current or no current) system, mark is no current. Makes idling more economical. -- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)
Reply by Jim Thompson May 16, 20092009-05-16
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. > >The idle state is constant Mark (positive or 0V, depending on whether it's >polar or neutral signaling). > >John's approach does take account of this.
If "Mark" is current in the solenoid, it's fine. (I'm obviously not at all familiar with Teletype... I'm not THAT old ;-) ...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.