Alt-BEAM Archive
Message #00053
To: "'beam@corp.sgi.com'" beam@corp.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Sun, 31 Jan 1999 09:52:37 -0800
Subject: [alt-beam] Re: a question and a comment
I tried my own suggestion and found the circuit below works very well.
It is much more sensitive than a single Nv and provides a minimum 0.5 sec
output
pulse which can be used to modify other processes. Forget about a single
inverter Nv with negative feedback as I suggested in my earlier post, it
oscillates too much during transistions.
______________________
| |
[10M] ___ ___ |
input 0.1 | ___|04 \__|04 \_|
signal ----||--+---' |___ / |___ / |
| |
[1M] |
| |
V |
0V----[10K]-----Vcc |
|
Adjustable sensitivity Nv |
_________________________________________|
|
| Vcc
| |
| _V_ LED
| |
| __ [1K]
| diode ____|04 \_____|_____ output pulse
+-->|--+----------+ |__ / >1sec
| |
[10M] === 0.1uf
| |
GND GND
Pulse stretching Nu
Fig 1 - A high pass/variable threshold detector
This is a variation on the Nv using two HC04 inverters in series to
give hysteresis and memory of the direction of the last fast transition
depending on the setting of the pot. To stretch the output signal (pulses) a
Nu is uses with a series diode and a parallel capacitor/resistor followed by
another HC04 gate to drive a LED or other load
These circuits are niffty little variations of the other basic BEAM
designs.
Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
tel: (604)590-7493
fax: (604)590-3411
> -----Original Message-----
> From: Wilf Rigter [SMTP:Wilf.Rigter@powertech.bc.ca]
> Sent: Saturday, January 30, 1999 3:47 PM
> To: beam@corp.sgi.com
> Subject: RE: a question and a comment
>
> This is an example of how easy it is (or HC240) gate : [Wilf Rigter]
> Snip
>
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