19 Jun
2011
19 Jun
'11
12:20 p.m.
The one I gave the link to, was for a similar purpose
-- checking the
speed of turntables for vinyl records -- though it could be used for
I guesed as much.
anything you can put a 50/60Hz strobe pattern on.
It's an elegant 2-IC
design (a CD4060 and a CD4013) that runs off a PP3 and fits in a small
standard box.
What does it use as the frequency reference? Does it use a crystal (and
if so, how does it handle the frequency change). What is the mark-space
ratio of the otuput (I found a narrow flash with a logner dark perid gave
a much clearier indication than a 1:1 ratio).
My circuit used, IIRC, a 4 pin oscillator module, a 'HCT 393 to divide it
down, a 'NCT 163 to ahdnle the /5 or /6 function (basically, it's
parallel-loadad with the appropraite value (switch-selected), it then
counts up until RCO is asserted whereupon it reloads), and a further
HCT163 to give a 1:15 mark-space ratio. The 74xxx are powered from a 7085
on the same bit of stripbpard. I used a 2N3904 to drive the white LEDs and
IIRC an other one as an inverter (probably fro the laod input of the first
'163) to avoifd hainv another IC package. The whole thing fits in a small
handheld case and runs off a 12V supply.
-tony