Hello John-Isaac,

I guess I should have included an explanation of the MaziBugV3 SE circuit
with the original post. The Maxibug part is straight forward so I have
attached just the SE part with waveforms below.

The Mazibug SE works similar to a FRED SE. The waveforms should help you get
the picture. Assume TP1-TP3 are at 0V (the blue line in the waveforms) to
start and Vcc is just rising above the voltage where the FLED starts to
conduct. The voltage at TP1 is generated by the current passing through R2
which is grounded at TP3. As Vcc rises, the FLED starts to pulse and every
pulse causes a voltage spike across R3. That voltage spike is coupled
through C1 to TP2. As Vcc continues the LED turns on and the DC voltage on
TP2 starts to ramp up. The pulses from TP1, superimposed on the DC voltage
of TP2, are used to "sample" the Vcc level and at some point (~4V) the
pulsed voltage on TP2 crosses the AC240 threshold shown in the TP2 waveform
with the green line.

When the 74AC240 is triggered, TP3 goes to Vcc and R2 bypasses the FLED. TP1
also rises to Vcc and TP2 rises to Vcc-1.3V=2.7V which is Vcc minus the
voltage drop across the LED. As Vcc drops to the reset level (2.6V) , the
voltage at TP2 crosses the 240 threshold level again and TP3 goes to ground.
Keep in mind that the 74AC240 threshold is about Vcc/2. The 74HC, HCT, ACT
types have lower thresholds and may require some adjustment.

The value of R1 can be 100K-1M and the value of R2 is between 5.1K-33K. For
testing use a 1000 ohm current limited 6V battery supply to simulate the
solar cell and a 3,300 uF cap for storage. Measure the voltage on the cap
with a voltmeter to determine the trigger and reset levels. I used a NPN
transistor and a small motor for a load for these tests. Remember, like the
FRED design, the FLED is sesnitive to light and should be shielded. FLED SEs
always require some fiddling to get them going but they do use commonly
available parts. Ofcourse a 1381 Mazibug would be much more predictable /
reliable.

wilf

----- Original Message -----
From: "isaac id" <sonofmumfy@...>
To: <beam@yahoogroups.com>
Sent: Saturday, March 22, 2003 4:59 PM
Subject: [beam] um, is this safe? half h bridge


> i've been doodling, and came up with a arrangement to
> make a single chip go a bit further. is it safe to use
> an h'bridge in this way?(half h.gif)
>
> i still am trying to get mazibug 3 to work (wilf's
> design) i don't know what i am doing wrong. i came up
> with a hybrid -mazibug[4]. if i understand correctly,
> the fled samples the voltage periodically and keeps
> the cap charged until the voltage drops far enough to
> stop the zener from working. then the 1M resistor
> pulls down the first inverter down.
>
> comments wilf?
> how is this for effeciency?
> john-isaac
>
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