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From: Tony Williams
Subject: Re: zero-power toggle circuit; was, how to master electronics
Date: Fri, 22 Nov 2002 12:15:20 +0000 (GMT)
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NNTP-Posting-Date: Fri, 22 Nov 2002 12:18:35 +0000 (UTC)
User-Agent: Pluto/1.14i (RISC-OS/3.60)
In article ,
Terry Pinnell wrote:
> This looks good! I simulated it with CircuitMaker using Tony's
> original component values. It worked fine from Vcc = 5 to 16 V with 22
> of the 32 MOSFET types I tested:
[snip exhaustive list]
Thank you Terry for all the work you have put in.
> I haven't investigated the reason(s) for the 10 failing to toggle.
Probable MOSFET fail reasons could be;
a) Total Fail; Model is wrong.
b) Ok at 16V, fail at low Vcc;
Not enough Vg-s available for that MOSFET at that current.
> Results are shown at
Thank you again.
If you have the time, keep trying to break it. Suggest;
a) Switch bounce. Use a narrow pulse (<1mS?), and increase
the repetition-rate until it fails to toggle properly.
b) On power-on it should always come up in the Off-state.
Because it is a simulation of the npn/pnp bistable,
(using a 4066 to simulate all-off "RTL" gates), then slow
power-on should be no problem.
The 100pF? on TG1's gate is there to try and ensure an
Off-state for fast power-on's (and to keep the last
toggled state, even during noise on the power suppy).
PS; There is a comp I'd like to add. A small diode,
pointing upwards from the top of C1 to Vcc. This is
to help protect the gate of TG1 (from the energy in C1)
during a fast power down.
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