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From: ntaib@silver.ucs.indiana.edu (Nur Iskandar Taib)
Newsgroups: rec.models.rc,sci.electronics
Subject: Re: Electric motor speed control
Message-ID: <1991Jan22.220317.12716@bronze.ucs.indiana.edu>
Date: 22 Jan 91 22:03:17 GMT
References: <1991Jan4.051028.24807@ux1.cso.uiuc.edu> <1991Jan18.183648.526@psuecl.bitnet>
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>3. Use a 2N2222 and TIP-31 (for up to 3 Amp capability) in the above setup
>   to switch the motor on and off in accordance with the PWM's output. Don't
>   forget a clamping diode across the motor's leads or else the spikes built
>   up across the motor could fry your TIP-31.


Hmmm... The TIP-31 could be replaced by a MOSFET
(Radio Shack sells the IRF-511 for $2) for lower
"on" resistance. 

Does anyone know how the 555 in a plug driver is
used? I tried to reverse-engineer an old Polk
power panel and it seems like they hooked it up
as a monostable instead of a regular oscillator. 
One of the advertised features of these power 
panels is the ability to send extra current to 
the plug when the plug gets wet (I suppose the 
lowered resistance is somehow used to increase 
the duty cycle of the pulse output on pin 3 of 
the 555). How is this done?



--
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Iskandar Taib                        | The only thing worse than Peach ala
Internet: NTAIB@AQUA.UCS.INDIANA.EDU |    Frog is Frog ala Peach
Bitnet:   NTAIB@IUBACS               !
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