I have a 556 servo driver circuit for a non-digital servo,
and it sends out about 50 pps centering around 1.5ms. I
also increased the resistance on the "edges" of the servo's
potentiometer (inside it's case), to make it more sensitive.
The timer varies per a 150 ohm coil connected with another
resistor between pins 6/7 and Vcc (the 555 pinout). The
servo offers excellent motion with little movement of the
magnet suspended inside of the 150ohm coil (it varies the
resistance by up to 50ohms). I am not working on making it
any more sensitive as I previously inquired! I want to do a
little twist though, to show it's receiving activity...
Servo Driver Circuitry
I would like to make a bar/dot meter (LM3915) that will light
more LEDs
as the pulse
widths change. I don't want it to
light according to position of the servo / duration of the width,
though if I have no other choices that would be better than
nothing. My idea is that if the seismometer starts to read a
signal (more sensitive than c 1/10 the servo's full range), the
LEDs will start to jump around like a VU meter, so it will grab
my attention from across the room. Again, ideally, it will light
more LEDs as the width's durations
fluctuate (e.g., if it's at
1.5ms <center> and suddenly jumps to say 1.55ms or 1.45ms,
one LED would light, and then if it stays in that area the LEDs
would subside). This way the meter would actually be relaying
"activity" as compared to position. If I can't have it that way, I
would be willing to go with it displaying servo position (though
it's actually showing the width of the pulse as compared to the
differences between the
string of pulses).
My problem. How can I integrate the above circuit link with my
coil/R4 between 6/7 and Vcc, by simply tapping into the servo's
signal line (I can't send power through or sense the coil's R,
because that would adversely affect the servo's sensitivity).
It's V is not going to be much or it may be up to the +V that the
servo gets?? (through a 7808), but it will be on for a very very
short duration and then off, 50 times a second. Any suggestions?