All About Circuits Forum Confusing Clap Switch System
 Register Blogs FAQ Members List Today's Posts Search Today's Posts Mark Forums Read

 Homework Help Stuck on a textbook question or coursework? Cramming for a test and need help understanding something? Post your questions and attempts here and let others help.

#1
11-07-2011, 02:04 PM
 NewbSolutions New Member Join Date: Nov 2011 Posts: 1
Confusing Clap Switch System

http://talkingelectronics.com/projec...TrCcts.html#37

I'm trying to understand how the circuit works(the clap switch circuit over there) for our basic electronics class but I'm having problems analyzing the circuit, since I don't really understand this part...

"...when a sound is detected, the negative excursion of the waveform takes the positive end of the 10u towards the 0v rail. The negative end of the 10u will actually go below 0v and this will pull the two 1N4148 diodes so the anode ends will have near to zero volts on them..."

...and pretty much everything in the explanation fails to penetrate my thick skull... I have a basic understanding of KVL, BJT analysis and diodes... though not capacitors outside AC circuits... since from my understanding they are supposed to block DC currents? though initially it allows them to pass through until the capacitor gets fully charged, in which case it will then block any more current from passing through... I also think those LEDs have a 10mA minimum current aside from the voltage drop(since they aren't ideal, I think... or is this only for zener diodes?).

also not really sure what happens to the electret mic when a sound is heard, though I think the capacitance of the capacitor hooked to the gate of the JFET changes? or something....

and shouldn't the two LEDs turn on at the start? since they'll pass through 270R, LED, capacitor(while it charges), the base->emitter portion of the BJT(since it functions as a diode if I remember correctly) until the capacitor dies, but then the BJT will then allow current from the collector to emitter for both of them?

I'm not really sure how this works....
and for the assignment, we're supposed to justify the values of the resistors, capacitors... so I'm not sure, though I think the 47k and 33k resistors are there to soak up most of the voltage so the current will be too small to power the LEDs? though not sure what difference the different capacitances of the capacitors do... or what the 270R resistors are for...

sorry, but I'm still very new at this so any help will be appreciated... I'm so sorry for being so inadequate ><

 Related Site Pages Section Title Worksheet Junction field-effect transistors Worksheet Class A BJT amplifiers Worksheet Bipolar junction transistors in active mode Worksheet Bipolar junction transistors as switches Worksheet Bipolar junction transistor theory Worksheet Characteristic Impedance Textbook Resonant filters : Filters Textbook The Shockley Diode : Thyristors Textbook Resonance in series-parallel circuits : Resonance Textbook Meter check of a transistor : Bipolar Junction Transistors

 Similar Threads Thread Thread Starter Forum Replies Last Post grovecat General Electronics Chat 7 12-04-2013 01:30 PM Melawrghk The Projects Forum 4 09-10-2010 04:49 PM falcon74 General Electronics Chat 1 08-27-2010 02:43 PM ron110 The Projects Forum 3 07-05-2009 05:40 PM notlag General Electronics Chat 1 04-09-2005 04:54 PM

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Electronics Forums     General Electronics Chat     The Projects Forum     Homework Help     Electronics Resources Software, Microcomputing, and Communications Forums     Programmer's Corner     Embedded Systems and Microcontrollers     Computing and Networks     Radio and Communications Circuits and Projects     The Completed Projects Collection Abstract Forums     Math     Physics     General Science All About Circuits Commmunity Forums     Off-Topic     The Flea Market     Feedback and Suggestions

All times are GMT. The time now is 07:18 AM.