More HEI HEI

[Bruce Bowling]

> 
> 
> And yes it will take a very low voltage to fire the circuit
> IN differential mode. Remember I am trying to fire
> this thing unbalanced. This means I must over
> come the DC bias on the transistor as well as
> provide the firing signal
> 
> 

I have not been following this thread, so forgive me if
the following info is not useful (or has been discussed
already, etc)....

I have triggered many different VR signal "inputs" with the
following circuit. This circuit will produce a waveform (bipolar)
which simulates (pretty closely) the output from a VR
sensor (I call it a "VR simulator"):

                ----------
 A>--- R -------|        |---------->
           |    |        |
           -    | 8    1K|
           C    | ohms   |            To VR Detect Circuit
           -    |        |
           |    |        |
 B>-------------|        |---------->
                ----------
               Audio Transformer

The input to A is a square-wave source with known duty
cycle (lets assume 0 to 5 volts). I put input B at
a midway voltage point (like 2.5 volts in this case).
You can use two resistors to do this voltage divider.
The resistor R and capacitor C act like a low-pass filter,
and values are chosen which converts the input
waveform (square) to a triangle wave. The transformer
will pass a dB/dt signal (of the triangle wave) to its
output (on the right). If you work the R and C values out
right (depends on the input waveform duty), you
will get out an output which looks like:

        /\                 /\
       /  \               /
-------    --    ---------    
             \  /
              \/

The nice thing about this is that the VR input (HEI module, etc)
sees a load which is similar to what it will get in the real world.
You can get the transformer at Radio Shack.

- Bruce

--
-----------------------------------------------------
<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
-----------------------------------------------------
                 Bruce A. Bowling
                 Staff Scientist
   Thomas Jefferson National Accelerator Facility
    12000 Jefferson Ave - Newport News, VA 23606
                 (804) 249-7240
bowling at cebaf.gov  http://devserve.cebaf.gov/~bowling
-----------------------------------------------------
<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
-----------------------------------------------------