Circuit Challenge of the Day
in [Design]
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From: Jim Thompson on 29 Dec 2009 15:18 On Tue, 29 Dec 2009 11:08:19 -0800, "Paul Hovnanian P.E." <paul(a)hovnanian.com> wrote: >Jim Thompson wrote: > >> Circuit Challenge of the Day >> >> The following circuit... >> >> http://analog-innovations.com/SED/RampGenerator_Amusement.pdf >> >> is a ramp generator. >> >> It is easy to see how the upper trip point circuitry causes discharge >> of the ramp. >> >> But what causes the turn-around at the bottom? >> >> ...Jim Thompson > >Q1 (and Q4) get turned on when the ramp reaches its peak. Q1 discharges C1. >When the voltage on C1 drops low enough, Q1's Vcb (a reverse biased diode) >gets forward biased. That causes Q1 to bogart all the base current flowing >through R3, leaving none for Q4 and it turns off. Pretty close. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Help save the environment! Please dispose of socialism responsibly! |