Hi Finn;
Did you read the 768mV P-P with or without your circuit attached?
Attached. I
just clipped the lead into the plug.
What's the counter chip you're using?
CD4522BE IC BCD DIVIDE-BY-N CNTR 16-DIP
I would imagine that you damaged it in your 20 volt tests, and it now clamps
Tracy's output to 0.7V (typical diode clamp voltage).
The one thats being used right now, was never
used on the breadboard. I've got 25 of 'em, so I used a different one for
no particular reason.
I thought the absolute max (power supply) ratings for CMOS chips (like 4000
and 74C.. series) were 18V.
This one
is rated for 20vdc according to the spec sheet.
Certainly TTL chips (74..) are limited to 5V supply (5.25V max).
Either that or you didn't read the scope right.
I recorded it in memory, and I can interface the
scope to my computer and send the image, for your interpretation. However
it is a fairly idiot proof instrument (that's why even I can make it work
:-) as it displays P/P, Max-P & Min-P along side of the waveform, so
it's not even really necessary to interpret the waveform
I actually had planned to take it back to the
airport and do further testing tomorrow. I'd planned to use both channel
A&B to record the input and output of the divider chip and record it
at various rpm's. After reading your post, I'd also like to read the output
without the counter chip attached.
I finally have an inspection scheduled for noon
tomorrow, so I'll be to busy to worry about this. I'll look into it next
week. Now that Rusty seems to have found a suitable tach, and soon Tracy
will be delivering the EM2 and also is considering a tach output for a conventional
tach, this probably is not really worth the effort, however I will still
experiment a little further if only for the educational value.
S. Todd Bartrim
Turbo 13B RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm