Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!lll-tis!ames!pasteur!ucbvax!cbosgd!mandrill!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: sci.electronics
Subject: Re: Voltage Controlled Amplifier IC
Message-ID: <984@neoucom.UUCP>
Date: 30 Jan 88 06:14:11 GMT
References: <341@gaia.UUCP> <975@neoucom.UUCP> <1512@osiris.UUCP>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 26
Summary: Light bulbs OK, twin tee good for SPICE bored rainy day emulation


Hi Max (et al),

Really, the light bulb doesn't bother me; I was just making a silly
comment. (sorry if I forgot the net-smiley face).  Those old #47
pilot lamps really could be used for all sorts of neat stuff when
you had a mind to...

Point well taken that a twin tee won't under work ideal conditions.
I found that using sloppily picked components is likely to yield a
concoction that has a higher probability of oscillating when the
power is switched on.  Fortunately, most hobbyists can't afford an
RLC bridge, thus odds are pretty good that there will be sufficient
mismatch for the thing to actually work.

Point also well taken that the twin tee exploits the nonlinearity
of the transistor to provide AGC after a fashion.  Well, with a
cruddy transistor like the 2N414 that I mentioned that approach was
reasonable.  That is also why the output should be taken between
the two capacitors on the tee, to minimize the harmonics sent to
the output.

A fun diversion for periods of rainy boredom would be to run the
old twin tee through spice with ideal and then real world component
values and see what happens.

--Bill