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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Tuesday, November 29, 2011 08:14 PM
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More
Voltage Converter;
Flyback Converter
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Voltage Converter - 0.5v to 6v |
Conventional silicon transistors just
can't operate at voltages less than about 0.7v. Old germanium transistors could be
used, but those are hard to find these days and most are rather large in size.
Some new n-channel MOSFET devices with very low gate-source threshold voltage can
operate at quite low voltages. I've been experimenting with various devices and
came up with one electronic circuit (shown below), which demonstrates how to boost
the low voltage from a single solar cell to a higher voltage. |
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below is a cheap single logic device from Texas Instruments. It turns out that
TI's 74AUC family of parts can work down to about 0.45 volts. I tried one of
their single schmitt trigger parts and found I was able to make on oscillator
function nicely at 0.5 volts. I then used a charge pump technique and a cheap
NPN transistor to form a low power flyback converter. This hobby circuit can
produce about 6 volts at the output from a 0.5v input.
The idea is to use this boost circuit to
generate the higher starting voltage needed by a much more powerful DC to DC
converter. Once started, part of the converter's output could then be feed back
to the input, to sustain converter operation. This is known as a "bootstrap"
technique. In the future, I hope to post a circuit which can supply several
watts of power from a 0.5v input voltage. This would be ideal for charging a
battery using power from a single large solar cell or several smaller cells
wired in parallel.
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Click on Drawing Below to view PDF version of Schematic |
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Voltage Converter; Flyback Converter
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eMail David A.
Johnson, P.E. about this circuit |
