Ok, I'll field a few of these..
On 7/25/2011 12:49 AM, Ryan McDonald wrote:
* Is there any reason to choose a 2x3 multiplex (mux) over 1x6? (Is a
1x6 prone to flicker or dim?)
Yes, 1x6 is prone to more flicker and to be dimmer than 2x3. I
personally consider 1x6 acceptable for me, but others are more particular.
* Although I'm an accomplisher programmer, I have very little
assembler and C++ background. Is PICbasic "good enough" for a clock?
I've looked at some sample code and it seems very understandable. Is
it fast enough? Does the PICbasic complier create bloated code
requiring a bigger uC?
Apparently picbasic _is_ good enough for a clock. I've never done it,
though, so I will have to let others give you the specifics. I always
program my AVR clocks in strict structural C.
* Is a uC with an xtal "accurate enough" or do you really need a
Dallas RTC?
Don't use an xtal. The preferred timing device is the 60hz mains
frequency. Mike Moorrees gave a post on this a little while back, but
the bottom-line is that the mains frequency is a LOT more accurate over
a year than an xtal (and only marginally less accurate than the TCXO).
* In a 1x6 mux, what is the known optimal voltage and current for
IN-14's? (Also, for a 2x3 mux?)
I'll let the man that did all of the experimentation on this answer for
you, but if you search the archives you should be able to find this
answer. Optimum depends on if you're wanting brighter or longer tube
life. multiplexing increases the tube life but dims the tubes.
* And during the final build, could you measure V&C while muxing, or
do you need to measure in direct drive tuning to the muxed values?
I would measure using direct drive if it is with a multimeter. (Or you
could use a scope and measure the peaks of the square wave).
* The previous 2 questions could simply be reduced to, "whats a good
anode V, and value for the anode resistor for IN-14's?" :)
Again, depends on your tastes. I usually use a 10k resistor with a
180vdc supply and 1x6 mux on IN-14's.. However you may find that to be
excessively dim and/or flickery for your tastes.
* What are some recommended on/off/delay times for a 1x6 and 2x3 mux
that both look good and maximize brightness without stressing the
IN-14's?
* Is it electrically correct just to throw a diode in series with each
anode to help minimize ghosting by reducing capacitance in the tube-
board?
I'll let Mike field this one. I think that the most important component
in minimizing ghosting is to provide enough delay between one tube
turning off and the next tube turning on.
* Whats a good duration& frequency to exercise a cathode for anti-
poisoning assuming normal operating V&C during the routine? I was
assuming a 0-though-9 cycle at the top of each hour where each cathode
is on 1 second. Is this reasonable?
Seems excessive. I'd set it up to grind through the anti-cathode
poisoning routines in the middle of the night, pick an hour and just run
solid for that hour. Although in the case of IN-14 (which are cheap and
soldered into the board) I'm not sure that anti-cathode poisoning
matters. The only reason I would mess with it is if you have menu
options (like on Moses' chip). If you occasionally display numbers on a
tube that never normally display that number during the clock's
operation, then you need anti-cathode poisoning. Otherwise, I don't
think it matters.
Yes, the cathodes that are unused will get poisoned... but if you never
use those cathodes, does it matter? (It doesn't).
* In anti-poisoning, is it better to do a 1-second continuous burn,
or .1 seconds ten times to increase strikes? Does it even matter?
I would use continuous burn.
Thanks for your responses. I've got the parts for my HVPSW on the way
so I can start breadboarding and light my first cathode. :)
I'm not sure I'd go with the 555, since I'm a fan of the MC34063, but
each to their own. :)
-Ryan
-Adam
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