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basic question

M

Mike_in_SD

Jan 1, 1970
0
the speed sendor/sensor on my streetrod transmission turns on and off
(pulses) 12v sending it to the speedometer.

I have an old scope that I barely know how to use .. and it shows
a nice square wave

with the speedo disconnected my fluke reads 6v
so I guess I am measuring average voltage.

now the problem

Im working on a project where I feed these pulses to a microprocessor

If I dont have the speedo connected and just connect the sender
to the micro .. it works fine.

but ..

when I connect the speedo and "tap" into the signal line
I only measure 1v and its not enough to trigger the micro

not sure what to do ..

thanks for any help
mike
 
E

ehsjr

Jan 1, 1970
0
Mike_in_SD said:
the speed sendor/sensor on my streetrod transmission turns on and off
(pulses) 12v sending it to the speedometer.

I have an old scope that I barely know how to use .. and it shows
a nice square wave

with the speedo disconnected my fluke reads 6v
so I guess I am measuring average voltage.

now the problem

Im working on a project where I feed these pulses to a microprocessor

If I dont have the speedo connected and just connect the sender
to the micro .. it works fine.

but ..

when I connect the speedo and "tap" into the signal line
I only measure 1v and its not enough to trigger the micro

not sure what to do ..

thanks for any help
mike

Opamp?

Ed
 
B

Bob Masta

Jan 1, 1970
0

CMOS buffer would be easier and better for square waves.
The ever-popular CD4049 has 6 in one package. These are
inverting buffers, so if polarity is important (which I doubt here),
use one of them to invert the sensor signal, and feed it to
the rest, which invert it back. You'll then have 5 copies of the
signal to use. You can parallel these as needed if one
destination needs more drive current.

Best regards.


Bob Masta

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!
 
M

Mike_in_SD

Jan 1, 1970
0
[email protected] (Bob Masta) wrote in <45d1c06f.2054715
@news.sysmatrix.net>:
CMOS buffer would be easier and better for square waves.
The ever-popular CD4049 has 6 in one package. These are
inverting buffers, so if polarity is important (which I doubt here),



Cool Bob .. I'll check that out .. thanks

mike
 
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