On Sat, 08 Nov 2008 07:52:44 -0700, Jim Thompson
wrote:
On Sat, 08 Nov 2008 07:12:58 -0600, John Fields
wrote:
On Fri, 07 Nov 2008 19:31:07 -0700, Jim Thompson
wrote:
On Fri, 07 Nov 2008 05:46:14 -0600, John Fields
wrote:
On Thu, 06 Nov 2008 15:45:43 -0600, John Fields
wrote:
---
A "gotcha" I noticed yesterday, or the day before is that, wired the way
it's shown, (with the register outputs sinking current) if all the
register outputs come up reset on power-on, then there won't be enough
current to turn on all the LEDs and you'll have to wait for an entire
cycle before the thing starts to chase properly. If you've got the pot
set to "full slow" that could take about 30 seconds, so it might be
working, but since nothing was appearing to happen it looked like it
wasn't working.
In order have it start right away the shift register outputs should
_source_ current, so I fixed the circuit and attached a copy of the new
schematic.
---
Dotting the 'i's and crossing the 't's yields rev b:
JF
John, Hate to be a party-pooper, but I believe, unless this starts
just right it doesn't work :-(
---
How so?
JF
Too many R/C's ?:-)
---
No, just enough, but you tease...
Still pushing buttons, eh?
The only thing I can come up with, which you might be referring to, is
the floating cap in the astable pushing nasty transients into the input
diodes which might foment lockup.
The solution?
Version 4
SHEET 1 2336 1540
WIRE -416 -496 -640 -496
WIRE -416 -448 -416 -496
WIRE -416 -336 -416 -384
WIRE -112 -336 -416 -336
WIRE -80 -336 -112 -336
WIRE 16 -336 -16 -336
WIRE 128 -336 16 -336
WIRE -112 -304 -112 -336
WIRE 16 -208 16 -336
WIRE 16 -208 0 -208
WIRE -112 -192 -112 -224
WIRE -112 -192 -144 -192
WIRE -64 -192 -112 -192
WIRE -416 -176 -416 -336
WIRE -368 -176 -416 -176
WIRE -256 -176 -288 -176
WIRE -208 -176 -256 -176
WIRE -640 -160 -640 -496
WIRE -416 -144 -416 -176
WIRE -256 -144 -256 -176
WIRE -640 -48 -640 -80
WIRE -416 -48 -416 -80
WIRE -416 -48 -640 -48
WIRE -256 -48 -256 -80
WIRE -256 -48 -416 -48
WIRE -640 0 -640 -48
FLAG -640 0 0
SYMBOL Digital\\or -176 -112 M180
SYMATTR InstName A2
SYMATTR Value2 trise 10e-9 tfall 10e-9 vhigh 5v
SYMBOL cap -16 -320 M270
WINDOW 0 64 34 VTop 0
WINDOW 3 64 34 VBottom 0
SYMATTR InstName C1
SYMATTR Value 6.8e-7
SYMBOL res -128 -208 M180
WINDOW 0 -47 68 Left 0
WINDOW 3 -54 34 Left 0
SYMATTR InstName R1
SYMATTR Value 1e6
SYMBOL Digital\\or -32 -128 M180
SYMATTR InstName A3
SYMATTR Value2 trise 10e-9 tfall 10e-9 vhigh 5v
SYMBOL schottky -400 -384 R180
WINDOW 0 61 34 Left 0
WINDOW 3 24 0 Left 0
SYMATTR InstName D17
SYMATTR Value CMDSH2-3
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL voltage -640 -176 R0
WINDOW 0 40 57 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL schottky -400 -80 R180
WINDOW 0 50 34 Left 0
WINDOW 3 24 0 Left 0
SYMATTR InstName D16
SYMATTR Value CMDSH2-3
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -272 -192 R90
WINDOW 0 -32 56 VBottom 0
WINDOW 3 -31 58 VTop 0
SYMATTR InstName R5
SYMATTR Value 1e4
SYMBOL cap -272 -144 R0
WINDOW 0 40 32 Left 0
SYMATTR InstName C3
SYMATTR Value 1e-9
TEXT -624 -24 Left 0 !.tran 10 uic
JF