Alt-BEAM Archive
Message #08514
To: beam@sgiblab.sgi.com
From: Dave Hrynkiw dave@solarbotics.com
Date: Mon, 20 Dec 1999 09:50:52 +0800
Subject: Solarbotics Miller Engines
Hi all.
In the rapid explosion of SE growth going on lately, here's our little
contribution. We recently licensed this solarengine design from the Mr.
Andrew Miller of AM Innovations. Simple and effective, we hope you enjoy =
it!
This circuit is available for private use only, and any commercial use mu=
st
be approved by us, the license holder.
Regards,
Dave Hrynkiw
Instructions:
The Solarbotics MILLER ENGINE (under license from AM Innovations)
The Miller Solarengine (MSE) is a simple, effective Type-1 solarengine wi=
th
a configurable discharge time that can drive both inductive and
non-inductive loads. The advantage of this solarengine is that it can all=
ow
for frequent very high level bursts of energy that last for only a set
period of time, rather than letting stored power run completely out as wi=
th
traditional 3904/3906 type solarengines. Originally designed by Andrew
Miller in 1995, this Solarengine design has been distilled to this most
optimum layout.
The 1381 drives a power transistor or FET via it's CMOS output for a peri=
od
determined by the value of the time discharge capacitor, C2.
The diode D1 is any standard signal diode (i.e.:1N914), which adds
approximately 0.7V to the trigger value of the 1381 selected (ie: C trigg=
er
is 2.2V trigger plus 0.7 =3D 2.9V trigger voltage). More diodes can be ad=
ded
in series to further increase the trigger voltage in 0.7V steps (for
standard signal diodes).
C1 should be a high value capacitor, along the lines of a 0.33F 2.5V
Panasonic Gold AL capacitor. If voltages required are higher than the cap
value, placing two in series is advisable (2 x 0.33F caps in series =3D 1=
cap
0.167F at 5V maximum rating).
C2 sets the hysterisis value (the on time) by keeping the voltage the 138=
1
sees above it's shut-off voltage. The value of C2 is highly dependant on
the drive component selected. For FETs, values of 0.1=B5F to 10=B5F give =
pulses
0.4 to 4 seconds long. When using BJT (standard) transistors, the capacit=
or
value should range anywhere from 47=B5F to 1000=B5F, giving pulses durati=
ons
between 0.4 to 2 seconds long. Experimentation is required based on your
device load.
Current limiting resistor R1 is only really necessary for designs using
transistors, and are optional for FET variations. 2.2k being standard,
other values of 470 ohm to 10k are quite suitable depending on your
application.
If low-voltage (lower than the 1381C set at 2.9V) operation is required, =
a
germanium diode can be used instead of the standard 1N914, which will low=
er
the voltage step from 0.7V to 0.4V. This means a 1381C setup will activat=
e
at approximately 2.6V rather than the 2.9V using a standard silicon diode.
For even lower voltage use, substitute a wire for the diode, and place a
20k resistor (R2) between the ground leg of the 1381 after C2 and the
ground rail. C2 will have to be raised appropriately, as it will now
discharge through the 1381 and the resistor.
-------------------------------------------------------------------------=
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----
> ---------------------------------------------------------------
> "Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
> that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
> 2 vowels. Pronounciation? _SMITH_".
> http://www.solarbotics.com
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