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Control Circuits

 
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Last Updated: October 24, 2017 02:54 PM

Circuits Designed by Dave Johnson, P.E.

Service Request BeeperA single press of a pushbutton switch turns on a beeper for one second but cant be activated again for 60 seconds. . . . Hobby Circuit designed by David Johnson P.E.-September, 2005

Servo Pulse to Voltage ConverterA while back a Discover Circuits visitor needed a way to convert servo pulses from a radio controlled device into a voltage.  The drawing below, illustrates the pulse train of the received signal.  The time between pulses is a fixed 20ms while the pulse widths vary from a low of 1ms to a high of 2ms . . . Hobby Circuit designed by Dave Johnson P.E.-August, 2005

Shadow activated (or hand wave) Motion DetectorThe circuit below works quite well in typical indoor room lighting.   I would not recommend its use in direct sunlight.   Two small PIN photodiodes positioned about one inch apart form a shadow detector.   With no shadow cast on the devices, both devices produce nearly identical current levels.   The current is converted to a voltage with two load resistors in parallel with the photodiode.   One resistor is adjustable to the two voltages can be carefully balanced under uniform lighting.Circuit Solution by David A. Johnson P.E.-August, 2005

Shop Safety LightMy 1200 square foot metal shop only has one small entrance door and no skylights.  If the lights are turn off while inside, there is not enough light to safely find the door to exit the building.  On a couple occasions, while I was quietly working at my test bench, my wife would walk into the shop, grab a garden tool and rush back out, turning off the lights and closing the door without thinking . . . Hobby Circuit designed by David Johnson P.E.-November, 2004


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

Service Request Beeper -  A single press of a pushbutton switch turns on a beeper for one second but cant be activated again for 60 seconds. . . . Hobby Circuit designed by David Johnson P.E.-September, 2005

Servo Controller -  This circuit can be used to manually turn a servo clockwise and anti-clockwise.  By pushing the forward or reverse button for a short period of time you can control the rotation of the servo.  __ 555-Timer

Servo loop improves linear-regulator efficiency -  8-Jul-04 EDN-Design Ideas Linear regulators are easy to implement and have better noise and drift characteristics than switching approaches.  Their largest disadvantage is inefficiency  excess energy dissipated as heat.  Several well-known techniques are available to minimize the input-to-output voltage across a linear regulator __ Circuit Design by Aurel Gontean, Technical University, Timisoara, Romania

Servo Motor Controller -  This is the simple basic design of servo motor controller with pulse generator.  It uses the CMOS IC 7555 in the Astable mode to generate pulses to drive the servo motor.  The circuit can be suitably modified to get pulses of sufficient length.  A Servo is a small device that has an output shaft.  This shaft can be positioned to __ Designed by D Mohankumar

Servo Motor Tester -  When using a servo motor in a project, if the servo motor does not respond as per the input, how to make sure that the fault is not in the servo...__ Electronics Projects for You

Servo Pulse to Voltage Converter -  A while back a Discover Circuits visitor needed a way to convert servo pulses from a radio controlled device into a voltage.  The drawing below, illustrates the pulse train of the received signal.  The time between pulses is a fixed 20ms while the pulse widths vary from a low of 1ms to a high of 2ms . . . Hobby Circuit designed by Dave Johnson P.E.-August, 2005

Servo Signal Trigger -  The main inspiration for setting up this site, this little creation allows you to effectively add functions to your existing R/C set-up for models, robots, model robots, etc.  I'm selling kits on Tindie along with a few assembled ones and some bare PCBs.  You can also Email me directly (see about page for contact details) and I'll sell you one for 5% less (ie.  without Tindie's charge), but this way I can only guarantee stock when I confirm your order. __ Designed by Kevin Koster

Servo Tester -  This circuit can be used to manually turn a servo clockwise and anti-clockwise.  By pushing the forward or reverse button for a short period of time you can control the rotation of the servo.  It will also test a servo.  __ 555-Timer

Servo Wiring Chart -  After 1991 or so (I can't remember) , most of the major brands of servos became compatible with each other.  You can use any of these brands of servos with any brand of receiver.  Some brands of servos are really great for a particular use in a particular plane, and there are other companies that sell their servos with each different 

Servo with lots of grunt -  Looking for a servo with a lot of grunt? This jumbo servo uses a robust 12V motor/gearbox assembly to give you real muscle.__ SiliconChip

Servo Tester -  A simple circuit based around one logic IC which will test/control most radio-control type servos __ Contact: P. Townshend EduTek Ltd

Servo-Constant-Current Drive Amplifier-Using Model 440C  -  No description, just schematicOpAmps Lab Inc is the manufactor ofAmplifiers (Video / Audio / Distribution / Microphone / Equalization / Line / VCA / Power), Switchers (Routing / Assign / Matrix), Mult (Press) (Network-Feed) Boxes, Audio Transformers, Oscillators, Power-Supplies, Custom Sub-Systems.  __ Application OpAmps Lab Inc.

Servo-Position-Using Model 423  -  No description, just schematicOpAmps Lab Inc is the manufactor ofAmplifiers (Video / Audio / Distribution / Microphone / Equalization / Line / VCA / Power), Switchers (Routing / Assign / Matrix), Mult (Press) (Network-Feed) Boxes, Audio Transformers, Oscillators, Power-Supplies, Custom Sub-Systems.  __ Application OpAmps Lab Inc.

Set Your Lights to Music -  6-Aug-09 EDN-Design Ideas This circuit activates six ac outlets according in a logarithmic thermometer-code format, causing six to 12 strings of lights to flash on and off according to the level and tempo of music you are playing __ Circuit Design by Hanif Saeed, Maxim Integrated Products, Inc, Sunnyvale, CA

Shadow activated (or hand wave) Motion Detector -  The circuit below works quite well in typical indoor room lighting.   I would not recommend its use in direct sunlight.   Two small PIN photodiodes positioned about one inch apart form a shadow detector.   With no shadow cast on the devices, both devices produce nearly identical current levels.   The current is converted to a voltage with two load resistors in parallel with the photodiode.   One resistor is adjustable to the two voltages can be carefully balanced under uniform lighting.Circuit Solution by David A. Johnson P.E.-August, 2005

Shock-Proof Remote Switch -  Using this circuit, you can control any AC/DC appliance remotely through inexpensive, low-voltage cabling and a standard push switch.  The circuit can easily support cable length up to 25 metres.__ Electronics Projects for You

Shop Safety Light -  My 1200 square foot metal shop only has one small entrance door and no skylights.  If the lights are turn off while inside, there is not enough light to safely find the door to exit the building.  On a couple occasions, while I was quietly working at my test bench, my wife would walk into the shop, grab a garden tool and rush back out, turning off the lights and closing the door without thinking . . . Hobby Circuit designed by David Johnson P.E.-November, 2004

Short DC power-line pulses afford remote control -  10/25/01 EDN-Design Ideas If you face the challenge of adding a second, independently controlled light source to an existing ceiling lamp controlled by a wall switch, you may find that stringing a second power line is impossible.  First, you can replace the wall switch by the circuit in Figure 1.  Pushing the on switch S1 or S2 for approximately 1 sec inserts the 12V zener diodes D1 or D2 in series with the __ Circuit Design by Tom Hornak, Portola Valley, CA

Silent Metronome -  File contains several designs, please scroll to find this circuit.  The circuit below is a "silent" metronome that keeps the beat without becoming a member of the band.  The circuit flashes the 6 volt lamp at a rate set by the 20k potentiometer which can have a dial for setting the desired tempo.  Alternately, the potentiometer could be replaced with a rotary switch and selected resistors.  The lamp is an ordinary #47 bulb which will give good omni directional brightness but an LED and resistor could be used insteadtry a 100 ohm in series with a   high-intensity LED.  The batteries could be three C or D cells for good life.  This circuit could be used to generate "clicks" in a speaker but such metronomes are not particularly pleasing.  The ambitious might replace the lamp with a solenoid which taps on the wall of a hardwood box or wooden chime for a "professional" sound.   __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Simple  RF Based Code Lock -  This simple radio frequency (RF) based code lock incorporates a pair of 433MHz ready made RF transmitter and receiver modules.  It is a remote-controlled and code-protected locking system.  The code is...__ Electronics Projects for You

Simple  Sensitive Remote Control Tester -  Here is a handy gadget for testing of infrared (IR) based remote control transmitters used for TVs and VCRs etc.  The IR signals from a remote control transmitter are sensed by the...__ Electronics Projects for You

Simple  Soldering Iron Temperature Regulator -  Soldering irons are available in different wattage and usually run at 230V AC mains.  However, these have no temperature control.  Low-voltage soldering irons (e.g., 12V) generally form part of a soldering...__ Electronics Projects for You

Simple  Stereo Level Indicator -  Usually, low-priced home stereo power amplifiers dont have output level indicators.  An output power level indicator can be added to each channel of these stereo power amplifiers.  As low levels of...__ Electronics Projects for You

Simple 7 band eqalizer -  Audio graphic equalizers are very common as commercial products (for Hi-fi, car audio and stage use) but circuits for them are very rarely published.  I didn't design this one but it's really very simple.  The details shown are for a 7 band but the principle can be extended to almost any number of bandsif you can find accurate enough components. __ Designed by Richard Torrens

Simple Automatic Water-Level Controller -  Water-level controllers are common nowadays.  The one described here is built around timer NE555 and inverter buffer CMOS IC CD4049.  It uses readily-available, low-cost components, and is easy to build and...__ Electronics Projects for You

Simple Circuit C acts as Dedicated Motor control -  09/11/98 EDN-Design Ideas (Scroll to find this circuit design)   Motion-control systems often use a PWM signal to control the duty cycle for a motor driver or amplifier module.  Typical designs generate the PWM signals using C with dedicated PWM output lines, such as the PIC16C65 (Microchip Technology, www.  microchip.  com) and the HC11 (Motorola Inc, www.  motorola.  com).  However, these C may have more features than necessary for a motion-control system with multiple degrees of freedom.   __ Circuit Design by Dylan Horvath, Gecko Sysytems Inc, Austin, TX

Simple Circuit 4-CH Remote Control -  You can construct your own long range infrared (IR) wireless remote using Motorola's MC145026 emitter and MC145027 detector chips.  With your remote you can control devices up to 20 feet (7 meters) away.  It operates similiarly to a TV remote.  You just point the emitter at the detector, push a transmit button.  The detector then interprets your data signal.  You can use this circuit to remotely turn on/off devices (like a motors, relays, home appliances).   __ Designed by Boondog web site

Simple Circuit allows long PWM soft starts -  02/01/07  EDN-Design Ideas Enhance timing accuracy of a switching regulator's start-up ramp __ Circuit Design by Robert N Buono, Aeolian Audio LLC, Bloomfield, NJ

Simple Circuit Audio Tone Control -  This very simple passive circuit provides a simple audio shaping function. It was described by Derek Bowers in Electronic Design in February, 2012.  __ Designed by Bob Cromwell

Simple Circuit Automatic-Shutoff Uses Few Components -  07/23/12 EDN-Design Ideas This auto-shutoff circuit uses a bare minimum of components.  You often need to include a timed automatic-turn-off circuit in battery-powered equipment to extend battery life.  Previously published Design Ideas for this function all involve many components   (references 1 through 7).  The circuit in Figure 1 is a simple automatic-shutoff add-on circuit featuring no quiescent current.   __ Circuit Design by Benabadji Noureddine

Simple Circuit Bidirectional DC Motor Speed Controller -  The LT1970 is a 500mA power op amp with precise externally controlled current limiting.  Separate control voltages program the sourcing and sinking current limit sense thresholds with 2% accuracy.  Output current may be boosted by adding external power transistors.  __ Linear Technology/Analog Devices App Note, Apr 5th 2010

Simple Circuit Bidirectional DC Motor Speed Controller Without a Tachometer -  For motor speed control without using a tachometer, the circuit in Figure 12 shows an approach.  Using the enable feature of the LT1970A, the drive to the motor can be removed periodically.  With no drive applied, the spinning motor presents a back EMF voltage proportional to its rotational speed.  The LT1782 is a tiny rail-to-rail __ Linear Technology/Analog Devices App Note, Dec 5th 2011

Simple Circuit boost converter generates -27 & -87V -  05/22/97 EDN-Design Ideas In modern telecommunications applications, the basic communications link to the home is becoming either digital or wireless.  The normal circuitry to control a telephone is moving from the central office to the home.  Subscriber-li __ Circuit Design by David Feller, Harris Semiconductor, Dallas, TX

Simple Circuit capacitance meter bins parts -  03/24/14EDN-Design Ideas This simple, elegant circuit lets you quickly sort through capacitorsThe heart of the circuit is the RS flipflop using 4093 NAND gates along with transistors Q1 and Q2,  which discharge the reference and test capacitors respectively.  The reference capacitor (CREF) and the test capacitor (CX) are charged from zero volts, followed by a reset pulse applied to the bases of Q1 and Q2 __ Circuit Design by Raju Baddi

Simple Circuit Color Organ -  A simple, satisfactory Color Organ can be built with a handful of cheap components.  This design features: no mains supply transformer, built-in microphone and three widely adjustable frequency bands obtained by means of very simple, passive filters for Bass, Middle and Treble __ Contact: Flavio Dellepiane, fladello @ tin.it

Simple Circuit Colour Organ -  This is a simple, one lamp colour organ.  It is far less complicated then the Three Channel Colour Organ.  It is simply a lamp controlled by an SCR.  It can be built in a few minutes, and combined with other circuits to make some pretty neat effects.   __ Designed by Aaron Cake

Simple Circuit Continuity Tester Fits Into Shirt Pocket -  10-Jan-08 EDN-Design Ideas A pocket-sized continuity tester responds quickly to shorts or opens and is protected against connection to a live circuit __ Circuit Design by Tom Wason, Phoenixville, PA

Simple Circuit control shuts down data-acquisition systE - M -  One of the most effective ways to reduce circuit power is to shut down unused components.  Some circuits with power-shutdown capability reduce supply current 1000-fold compared with normal operation.  Placing data-conversion and support components in shutdown between conversions or when conversions are unnecessary significantly reduces supply current and average dissipation.    __ Circuit Design by Kevin Hoskins, Linear Technology Corp, Milpitas, CA  March 14, 1997

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

 


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