Hello, I've been working on learning Electricity & Electronics and using Forrest Mims' Electronics Learning Lab. I was doing good with only a few struggles that I slowly worked out but now I'm hit by a truck. I've been trying to figure out for weeks now, precisely how the astable multivibrator works. Attached is the schematic for the curcuit used in the lab.
I'm going to tell you what I think is happening, where I'm confused, etc. I'd like for someone to tell me where I'm thinking wrong and what I need to study more. I feel like I'm just forgetting some basic rule or never understood a particular component in the first place. Hopefully with a little guidance, I'll see the error in my thinking and be able to move forward in my studies.
In this curcuit, I understand that inconsistancies in manufacturing will cause one transistor to conduct before the other. Like all the other websites, I'll assume Q1 conducts first. I *think* that as Q1 is conducting, C1 is charging, that charge creating a negative potential on it's other plate. When that negative potential is strong enough, Q2 will turn on. I don't get what turns Q1 off at this point. Does C2 draw all the current once Q2 starts to conduct, not allowing anything to go through Q1?
I also don't understand how either Q1 or Q2's base dosen't see themselves as grounded through R2/R3 and just both be on.
I just don't understand what's going on and what I missed while studying capacitors & transistors.
Thanks for anyones help!
I'm going to tell you what I think is happening, where I'm confused, etc. I'd like for someone to tell me where I'm thinking wrong and what I need to study more. I feel like I'm just forgetting some basic rule or never understood a particular component in the first place. Hopefully with a little guidance, I'll see the error in my thinking and be able to move forward in my studies.
In this curcuit, I understand that inconsistancies in manufacturing will cause one transistor to conduct before the other. Like all the other websites, I'll assume Q1 conducts first. I *think* that as Q1 is conducting, C1 is charging, that charge creating a negative potential on it's other plate. When that negative potential is strong enough, Q2 will turn on. I don't get what turns Q1 off at this point. Does C2 draw all the current once Q2 starts to conduct, not allowing anything to go through Q1?
I also don't understand how either Q1 or Q2's base dosen't see themselves as grounded through R2/R3 and just both be on.
I just don't understand what's going on and what I missed while studying capacitors & transistors.
Thanks for anyones help!
Attachments
-
22.6 KB Views: 122