[time-nuts] TBolt Monitor

[Neville Michie]

The clock displays are of two types. The analogue dials use alternate  
negative and positive pulses
and are easily generated with a 0.5 Hz square wave signal. These  
dials are either slaves from master clock systems or
a cheap quartz clock dial with leads to the driver coil. A totem pole  
driver drives a capacitor that delivers
the appropriate impulse to the dial motor. This can be conveniently  
generated by a PPS signal straight from the TBolt.
The other display is a series of decimal counters decoded to produce  
a 60 X 60 X 24 display. This also can be driven
from the PPS from the TBolt.
The problem is setting either clock to UTC (or local time). A pulse  
counting system can always either miss a pulse or
respond to a glitch to get the count out of sequence. A two phase  
clocking system can reduce this problem but there
still remains the problem of start up and confidence checking.
The TBolt could just drive the displays directly, but loss of signal  
or power drop-out requires a procedure to resynchronise
the indicators and it would be better to have the displays autonomous  
in the absence of the GPS timing. I am thinking of a TCXO
to carry over the timing for long power failures, that can be done  
with a milliwatt.
Leap seconds are another consideration, so what I think might be most  
useful is a BCD seconds output from the monitor.
This could be jammed into the pulse counter to correct it and could  
be decoded to give one minute pips like WWV to set
an analogue dial.
Just having a low power monitor indicating UTC is 99% of the required  
solution.
All of this is the alternative to running a PC to support the TBolt  
and so avoid the power demand and inconvenient size of the PC.
So what I want is a tiny black box to connect to the TBolt that would  
indicate UTC. Constructing a micro project is no problem,
but the program development and installation is a sticking point.
cheers, Neville Michie

On 06/10/2008, at 3:08 AM, Didier Juges wrote:

> Tell me what kind of signal you need to drive your clock, and I may  
> be able
> to get what you need from the processor.
>
> Didier KO4BB
>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com
>> [mailto:time-nuts-bounces at febo.com] On Behalf Of Neville Michie
>> Sent: Sunday, October 05, 2008 6:34 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: [time-nuts] TBolt Monitor
>>
>> Hi,
>> I have been having fun with my TBolt, and I am organising a
>> power supply to run it off a 12 volt battery backed up power supply.
>> I am making my own low headroom regulators, I assume it will
>> perform better with precisely controlled supply voltages.
>> What I need next is a monitor to show the current UTC time
>> and perhaps a monitor function or two.
>> That will be used to set  a PPS counting clock which is for
>> setting my clocks while I use the 10 MHz to drive a time
>> stamping logger that records the timing of the escapements of
>> the clocks (pendulum type) being analysed.
>> I saw the monitor Didier was proposing, but my skills with
>> micros are quite limited so are there any suggestions for a
>> low power, simple monitor that I can recover UTC with to set
>> my PPS counting clock? The clock will be either or both of a
>> seconds indicating slave dial and a 6 digit large LED display.
>> cheers,
>> Neville Michie
>>
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