All About Circuits Forum  

Go Back   All About Circuits Forum > Electronics Forums > General Electronics Chat

Notices

General Electronics Chat Discussion forum for general chat about anything electronics related, including asking questions about material in the All About Circuits E-book, Worksheets, and Videos.

Reply   Post New Thread
 
Thread Tools Display Modes
  #1  
Old 09-30-2013, 04:51 PM
Joster Joster is offline
Member
 
Join Date: Jun 2013
Posts: 62
Default Help with Comparator and MOSFET Circuit!!

Hi All,

I'm hoping someone can help me out with getting this circuit going. I'm trying to use a comparator to sense the voltage of a capacitor and then discharge it into a battery.

I have the comparator set up but the output voltage range is not what I expected. I'm running the LM371 with a 9V battery and my out switches from 1.2V to 7.7V. I understand this is actually what the comparaotor output voltage looks like as it is not ideal.

So I figured I would connected the output to an H11D1 and use 720 Ohms in series from the output of the comparator to the in of the H11D1 to only reach I(f) (which is 10mA) when the opamp goes high. This did work but the resistance between the collector and emitter of the H11D1 ranged from 300 Ohms to 3.7K. So I guess it's not being driven fully into saturation or cut off?

I'm sure you can tell I'm pretty lost in this but I'm frustrated because its such a simple process and what I understand should be happening is not at all.

I graduated from as an Electronics Technician with Honors 5 years ago so I'm pretty bummed that I can't figure this out.


Any help would be great thanks!

Joe
Reply With Quote
  #2  
Old 09-30-2013, 04:57 PM
crutschow's Avatar
crutschow crutschow is offline
Senior Member
 
Join Date: Mar 2008
Location: L.A. USA
Posts: 6,318
Blog Entries: 1
Default

Post a schematic.
__________________
Zapper
Curmudgeon Elektroniker
Reply With Quote
Reply   Post New Thread

Tags
, ,


Related Site Pages
Section Title
Worksheet Digital-to-Analog conversion
Worksheet CMOS logic gates
Worksheet Inverting and noninverting opamp voltage amplifier circuits
Worksheet Power conversion circuits
Worksheet Insulated gate field-effect transistors
Worksheet Class A BJT amplifiers
Worksheet Th'evenin's, Norton's, and Maximum Power Transfer theorems
Textbook The common-emitter amplifier : Bipolar Junction Transistors
Textbook Ohm's Law : Basic Concepts And Test Equipment
Textbook Computer simulation of electric circuits : Ohm's Law


Thread Tools
Display Modes

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 Jump


All times are GMT. The time now is 02:45 PM.


User-posted content, unless source quoted, is licensed under a Creative Commons Public Domain License.
Powered by vBulletin
Copyright ©2000 - 2014, vBulletin Solutions, Inc.