Alt-BEAM Archive
Message #00312
To: beam@corp.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Wed, 10 Feb 1999 00:51:49 -0800
Subject: [alt-beam] Mono Nv Neuron
content-type: text/plain
Someone asked me how sensitive the N/2 neuron is to high frequencies. The
question should really be "How sensitive is a Nv to high frequencies?" since
the Nv is the input element of the N/2.
A conventional Nv is very sensitive to high frequency noise on the input
when a "process" is active and at a point on the capacitor discharge curve
when the voltage at the bias point is near the switching threshold. Then
even a small noise spike can cause an early trigger disturbing the time out.
In addition a conventional Nv gives a badly chopped up output, when reset
and retriggered at every input +/- transistion shorter in duration than
NvTC.
So here is a ruggedized Nv Neuron which I designed for the input of a N/2
counting chain. This novel circuit has no restriction on input vs output
pulse width and is insensitive to input noise. It is a non-retriggerable
monostable Nv Neuron. Once a negative transistion occurs on IN, then OUT
stays low for NvTC (RC) even if there are multiple transistions at the
input during the period NvTC after the Nv is triggered. Since the timing
element RC are not connected to the input, the time constant is stable and
not affected by noise at the input. As you can see the input components can
be made very small since they only required to trigger the main Nv process
controlled by R and C. The ASCII version shows AND gate version with active
low input and output. The GIF (1KB) shows a Mono Nv stage using the HC32 and
a HC04 to provide the equivalent of a Nv microcore stage.
Vcc________________
| |
| [R] C
[10K] |________||___
| | __ || |
IN ____||_|___ +-|08 \_______|__ OUT to XOR
|| `------|__ /
.001
FIG 1 - Mono Nv NEURON
<>
enjoy
Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
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Attachment: rugNv.gif
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