Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com, has 45,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.
We make every effort to link to original material posted by the designer. 
Please let us if you would like us to link to or post your design.

HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches



Control
Circuits

 
#'s - A       B - C       D - G        H - L       M - P        Q - S        T - U        V - Z
 

Last Updated: December 07, 2017 02:04 PM

Circuits Designed by Dave Johnson, P.E.

Freeze AlarmI chose an accurate thermistor from Keystone as the temperature sensor for this circuit.  This device has a very specific resistance at a particular temperature.  According to the data sheet for the thermistor, the device will have a resistance of 361K at zero degrees C, which is the freezing point of water.  The thermistor is wired into a simple bridge circuit, which uses 1% resistors.  The bridge is connected to a very low power voltage comparator.  The circuit forms a switch circuit, which changes state, when the resistance of the thermistor reaches a certain value.  At zero degrees C the voltage at the non-inverting input of the comparator exceedsCircuit Solution by David Johnson P.E.-May, 2006

Freezer Over-Temperature AlarmThis circuit turns on a beeper whenever the inside temperature of a freezer is greater than zero degrees Centigrade.  The circuit draws only a few microamps from a 9 volt battery.  It uses a glass bead thermistor accurate to 1 degree C.. . . Circuit by Dave Johnson P.E.-November, 2014

Freezing Temperature AlarmThe circuit below is designed to activate a beeper alarm, whenever the outside air temperature is below 0 degrees C (32F).    A 9v battery powers the circuit.    The average 9ua current is so low that the battery should last for many years.. . . Circuit by David Johnson P.E.-November, 2014




Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Four-Watt AF Amplifer -  I have recently included a page about AF amplifers for use with Homebrew rigs.  In this I mentioned that I may include a practical one-watt circuit, complete with PCB foil and layout.  Here it is, but I have taken the liberty of engineering it to provide 4-watts of AF output and with a frequency response almost suitable for Hi-Fi applications __ Designed by Harry Lythall-SM0VPO

Four-way remote control uses series transmission -  01/18/01 EDN-Design Ideas A simultaneous fourway remote-control system adheres to size,  cost, and reduced-complexity   constraints and uses a series transmission to drive parallel loads  (Figure 1).  You can use.   PDF has several circuits, scroll down.    __ Circuit Design by JM Terrade, Clermont-Ferrand, France

FOXBOX Transmitter Controller -  This FOX-BOX is based on a single CMOS 555 timer and uses an ISD1000 chip to store the transmit ID.   __ Designed by Joe Leggio WB2HOL

FPGA Memory Controller Links Embedded µP to Cache-Enhanced DRA -  01/19/95 EDN-Design Ideas DRAM chips often lack the performance that embedded systems require.  Also, SRAM takes up too much space and is too expensive for any application using over 1 Mbyte of memory.  But designers have another option: a memory built with DRAM enhanced with an on- __ Circuit Design by James Joseph and Charles Brown, Ramtron International Corp, Intel Corp

Freeze Alarm -  I chose an accurate thermistor from Keystone as the temperature sensor for this circuit.  This device has a very specific resistance at a particular temperature.  According to the data sheet for the thermistor, the device will have a resistance of 361K at zero degrees C, which is the freezing point of water.  The thermistor is wired into a simple bridge circuit, which uses 1% resistors.  The bridge is connected to a very low power voltage comparator.  The circuit forms a switch circuit, which changes state, when the resistance of the thermistor reaches a certain value.  At zero degrees C the voltage at the non-inverting input of the comparator exceedsCircuit Solution by David Johnson P.E.-May, 2006

Freezer Over-Temperature Alarm -  This circuit turns on a beeper whenever the inside temperature of a freezer is greater than zero degrees Centigrade.  The circuit draws only a few microamps from a 9 volt battery.  It uses a glass bead thermistor accurate to 1 degree C.. . . Circuit by Dave Johnson P.E.-November, 2014

Freezing Temperature Alarm -  The circuit below is designed to activate a beeper alarm, whenever the outside air temperature is below 0 degrees C (32F).    A 9v battery powers the circuit.    The average 9ua current is so low that the battery should last for many years.. . . Circuit by David Johnson P.E.-November, 2014

Fridge Door Alarm -  This fridge door alarm is using a 3V battery supply should be placed (in a small box) in the fridge near the lamp or close to the opening.  With the door closed the photo resistor R2 presents a high resistance (>200K) thus clamping IC1 by holding C1 fully charged across R1 and D1.  When a beam of light enters from the opening,  __ Designed by Popescu Marian

Fridge door Alarm -  Beeps if you leave open the door over 20 seconds; 3V battery operation, simple circuitry __ Contact: Flavio Dellepiane, fladello @ tin.it

Fridge door Alarm (2nd Version) -  Alternative version of the popular circuit; 3V battery supplyStill operating at 1.3V __ Contact: Flavio Dellepiane, fladello @ tin.it

Fridge Saver -  This circuit waits 5 minutes before re-applying the power to a refrigerator to prevent it from having to start up under pressure after a brief power outage.  This is highly stressful for the compressor and the thermal cut-out switch built into the compress __ Designed by Andrew R. Morris

Fridge Saver -  This circuit waits 5 minutes before re-applying the power to a refrigerator to prevent it from having to start up under pressure after a brief power outage.    This is highly stressful for the compressor and the thermal cut-out switch built into the compressor.    This device prevents frequent brief power interruptions __ Designed by Andrew R. Morris

Frost Alarm -  The thermistor used has a resistance of 15k at 25 degrees and 45k at 0 degrees celsius.  A suitable bead type thermistor is found in the Maplin catalogue.  The 100k pot allows this circuit to trigger over a wide range of temperatures.  A slight amount of hysteresis is provided by inclusion of the 270k resistor.  This prevents relay chatter when temperature is near the switching threshold of this circuit __ Designed by Andy Collison

Full bridge for motor control -  Before trying to understand a full bridge circuit, you may care to read up on PWM controllers, which page also describes how a half-bridge circuit works.  Most full bridge motor controllers also use pwm! Designing a full-bridge PWM circuit that is reliable and 'user-proof' is actually quite difficult! 4QD released our first such controller in 1992: it was probably not the first but was certainly early in the race. __ Designed by Richard Torrens

Full Color USB LED-Controller -  Microcontroller : Microchip PIC18F2550 Sensor : DS18S20 temperature sensor Video: Temperature based color control CPU load based color control Screen based color control License: The source code of this work is licensed under a __ Designed by Steffen Schütte

Full-featured Dual Hbridge -  Dueal non-shortin H-bridge with brake

Full-Wave Active Rectifier Requires No Diodes -  A full-wave rectifier can be built without using any diodes.  It exploits the fact that the output voltage of certain single- supply op amps is effectively clamped to ground (0 V) when the input signal goes negative.   __ Designed by Anthony H. Smith

Full-wave rectifier has programmable gain -  11/09/00 EDN-Design Ideas The traditional approach to the design of a full-wave rectifier(Figure 1) is to set the gains of IC1 and IC2 to 1 and use the.   PDF contains multiple circuits, scroll to find the one of interest __ Circuit Design by Chuck and Chris Wojslaw, Xicor Inc, Milpitas, CA

Fuzzy Set Point Controller-Act -  03/16/95 EDN-Design Ideas This is the third and final installment of our fuzzy design example.  We are designing a simple, fuzzy controller that charges a capacitor through a resistor/inductor series combination.  The controller senses proportional (P), differential (D), and integral (I) values of the error and processes them with two fuzzy rulebases, one for the P and D terms,  __ Circuit Design by David Brubaker, Fuzzy-Logic Contributing Editor

      <<<         >>>

Control Circuits:   #'s - A       B - C       D - G        H - L       M - P        Q - S        T - U        V - Z


HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |    Privacy Policy


Copyright  January, 1998 - December, 2017     David A. Johnson & Associates.  All Rights reserved. 


 Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.