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Hi
Finn;
It is a CMOS device capable of handling 20vdc on its VDD
pin. So I didn't feel it was necessary. In reality I found it was unstable when
VDD was less than 5vdc or greater than 11vdc, so since I had a bag of 470ohm
resistors handy, I just put a voltage divider on the VDD. With a regulated
13.8vdc it gives me just under 7 volts and a stable reading.
a side note; I originally had an internally regulated
alternator but the regulator failed (have since converted to an external reg as
per "electric Bob"). When running with the alternator tripped and less than
12vdc, I found the tach would become erratic at high RPM's, due to a low VDD.
When alt is charging, everything is fine.
S. Todd Bartrim
Turbo 13B RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm
"Whatever you vividly imagine, Ardently desire, Sincerely believe in,
Enthusiastically act upon, Must inevitably come to pass".
I don't see a Zener diode to clamp any
spikes.
Finn
Haywire wrote:
Attached are a couple of pics of my tach divider.
It can be set to divide by any number necessary. I can't guarantee it would
work with any tach but it works very well with my cheap
off-the-shelf-at-any-autoparts-store, Hastings tach. I have a few more if
anybody wants one.
S. Todd Bartrim
Turbo 13B RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm
"Whatever you vividly imagine, Ardently desire, Sincerely believe in,
Enthusiastically act upon, Must inevitably come to pass".
The EC-2 tach
output has 12 pulses per revolution, and won't directly work with any
normal tach. Todd has made a divider to bring the pulse rate down to
normal, and it sounds like it's working well. The TT that you have
expects 1 pulse per rev, so if you don't mind dividing the rpm reading by
12... :-)
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