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From: Robert Baer
X-Mailer: Mozilla 4.75 [en] (Win98; U)
Subject: Re: transistor help
Date: Fri, 18 Oct 2002 23:28:46 GMT
NNTP-Posting-Date: Fri, 18 Oct 2002 16:28:46 PDT
Organization: EarthLink Inc. -- http://www.EarthLink.net
Not Tesla wrote:
> I hope you can help us with this transistor/relay snag; here's how we want
> this circuit to perform; when wind crosses the fan and counter-rotates the
> engine, it will send a microcurrent (sub 5 mW) to the FET. The FET will then
> open the gate allowing the battery (3-9V) to light the led. When the fan
> stops, the gate closes and the led goes off.
> I have included a rough schematic.
> Do you have a perfboard/transistor/relay solution for this application?
Err....Using a "reasonable" fan, the output may be large enough to
*directly* light the LED; blade and fan selection may be in order - this
depends a lot on the air flow rate.
I put "reasonable" in quotes, because some fans are not simple and use
a hall effect devices to determine the rotor position for controlling an
electronic commutator; I do not think that any of those can be used as
Another way is to use a microswitch and attach a "leaf" on its arm;
the moving air moves the "leaf" causing the switch to close, and all you
need is a resistor in series from the battery to the LED to limit the
current (5-10 mA).
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