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

DiscoverCircuits.com has links to 45,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.

HOME Schematics Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches
Welcome to DiscoverCircuits.com - online since 2002

See Media Kit for
Advertising Opportunities

Attention Designers:  Please alert us by eMail if we have linked to sites
where your original material has been copied without your permission.
We will change to the LINK to your site.  
Thank you.

 


Light Dependent Resistor Circuits / Photocell Circuits
Light Dependent Circuits:  #'s - D      E - L      M- Z


Last Updated: October 13, 2017 03:07 AM

Circuits Designed by Dave Johnson, P.E. :

10mhz to 20mhz Laser Light DetectorThis circuit was originally designed to detect laser light pulses for an optical Ethernet communications system.  It has good ambient light immunity. . . Circuit by David A. Johnson P.E.-June, 2000

10Mhz to 20Mhz Light ReceiverLight power to volts conversion = APPROX.15mV per microwatt at 850nM. . . Circuit by David A. Johnson P.E.-July, 2006

12 Volt Lite/Dark Lamp SwitchOften, for certain low voltage lighting systems; you would like to turn off the lights during the bright light of the day.  Most commercial day/night switches are designed for AC lighting.  The circuit below was designed for a 12v DC system.  But, it could be modified for other voltage as well.  It uses an inexpensive phototransistor as the light detector. . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2008

12v Light/Dark Lamp SwitchAt night, this circuit will route current to a 12v lamp, turning it on. . . Circuit by David A. Johnson P.E.-July, 2006

12v Touch Switch Exciter CircuitThis circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits.    It can support a cable length of about 2500 feet.    A typical remote switch circuit is also shown as well as a receiver circuit for those switches.. . . Circuit by David A. Johnson P.E.-February, 2002

12v-24v AC & DC Day/Night SwitchThe circuit uses a bridge rectifier circuit to convert AC into DC.  A 12v zener diode limits the operating voltage of the circuit to 12v.  A tiny Schmitt trigger inverter and a phototransistor detects the ambient light intensity.  If there is sufficient light, the inverter disables a push-pull oscillator circuit . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2012

1Khz to Over 70Mhz Light ReceiverThis circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response.  It is designed around a PIN photo diode that is packaged for use with plastic optical fibers.  It can be used as an optical fiber receiver.  By using the open end of the optical fiber it can "sniff" out any modulated light signals . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

1us Light Pulse ReceiverThis circuit is designed to detect very weak light pulses lasting 1uS.  It uses a tuned LC feedback network to provide high sensitivity while giving high ambient light immunity.  A post voltage amplifier is included with a gain of about X20 . . . Hobby Circuit designed by David A. Johnson P.E.-March, 1999

1uS Light Pulse Receiver + Post AmpThis circuit is designed to detect very weak light pulses lasting 1uS.  It uses a tuned LC feedback network to provide high sensitivity while giving high ambient light immunity.  A post voltage amplifier is included with a gain of about X20.  The circuit is described in more detail in the receiver section of my Handbook of Optical Through the Air Communications.    Note: The LF357 op amp is no longer available, this circuit is for reference only.. . . Circuit by David Johnson P.E.-March, 1999

1W White LED Night LightAs many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components.  This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by David Johnson P.E.-November, 2008

20Mhz VCSEL 3mw Laser Test CircuitThis circuit takes advantage of some new vertical cavity surface emitting lasers   (VCSEL) that donít require light output control circuits.  The circuit shows how to drive the device from a single high speed CMOS IC. . . Circuit by David A. Johnson P.E.-June, 2000

24 Volt Day Night SwitchMany low voltage outdoor lighting systems use 24vac to power the devices.  The low voltage is much safer to use outside than standard 120vac or 240vac power systems.  The circuit below is designed to turn off power to outdoor lights during daylight and turn them back on at night . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2010

24v NiMH Battery Charger using a 12v Solar Panel A while back I received an email from a guy in the UK.  He wanted to use a small solar panel, designed to charge 12v lead acid batteries, but use it to charge a 24v battery pack.  His 24v battery pack used 20 AA size NiMH cells.  He went on to explain that his 20 cell NiMH battery pack was used very infrequently . . . Hobby Circuit designed by David A. Johnson P.E.-October, 2011

2Mhz Broad Band Optical Fiber ReceiverIf you need more sensitivity than the above circuit this circuit provides about ten times more gain.  It too is designed around an inexpensive plastic optical fiber detector . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

30Khz Light Receiver AmpThis circuit uses NPN darlington transistor to amplify the signal produced from short light flashes, as detected by a PIN photo diode.  The circuit draws only about 330uA from a 6v battery. . . Circuit by David Johnson P.E.-March, 2002

3mw Laser Test-20Mhz VCSE - LThis circuit takes advantage of some new vertical cavity surface emitting lasers   (VCSEL) that donít require light output control circuits.  The circuit shows how to drive the device from a single high speed CMOS IC . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

40Khz Burst Laser Diode DriverSome laser tag or simulated combat games can use this circuit to send short bursts of modulated laser light at the opponent's vest, equipped with a matching light receiver.  The circuit operates from three 1.5v cells   (4.5v) that should provide enough energy . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

40Khz Laser Burst DetectorThis circuit was originally designed to detect weak flashed of laser light bounced off of a fabric video projection screen.  It was used as part of a firearm training system.  It generates a 100mS output pulse whenever it detects a 3ms to 5ms-laser burst,. . . Circuit by Dave Johnson P.E.-June, 2000

40Khz Light Detector with High Ambient Light ImmunityThis circuit is designed for detecting infrared light modulated at around 40KHz.  Itís feedback scheme cancels much of the DC component from ambient light.  Itís conversion factor is about 100 millivolts per microwatt of 900nm light.. . . Circuit by Dave Johnson P.E.-July, 2006

40KHz Light Receiver Front-End CircuitThis circuit uses a unique cascode amplifier circuit to convert the current from a PIN photo diode to a current without any feedback network.  It is very stable and very sensitive.  This hobby circuit shown has the potential for a conversion factor of 10 volts per microwatt at 900nm.  I included a simple JFET post-amplifier with a gain of about 20.. . . Circuit by David Johnson P.E.-June, 2000

40KHz Modulated Light DetectorIf you want even more sensitivity than the above circuit, try this design.  When used with a one centimeter square photodiode, you can achieve a range of several hundred feet with a standard TV or VCR remote control module. . . Circuit by Dave Johnson P.E.-March, 1999

40khz TV-VCR Light Source RepeaterThis circuit is designed to be placed directly in front of a standard TV or VCR remote.  The exiting light pulses produced by the circuit match the pulses from the remote but are about 10 times more powerful.  Using the device, the remote can operate a TV or VCR over three times the normal distance. . . Circuit by David Johnson P.E.-June, 2000

50Mhz Broad Band Optical Fiber Receiver Version AIf the above circuit it still too slow, you can try this circuit.  What it lacks in sensitivity it makes up for in speed.  The circuit attaches a plastic fiber optic PIN photodiode assembly to a small box containing a small 3v battery and a standard. . . Circuit by David A. Johnson P.E.-June, 2000

5Mhz Broad Band  Optical Fiber ReceiverThis circuit is a simple broad band light detector that uses a very inexpensive IC and a PIN photodiode that is packaged for use with plastic optical fibers.  It has a bandwidth from 1KHz to over 5MHz.  It is great for experimenting with various modulated. . . Circuit by Dave Johnson P.E.-June, 2000

6V to 24V DC Day/Night SwitchUsing an inexpensive phototransistor, this circuit switches 12v to 24v power to a load, whenever the sun goes down. . . Circuit by David Johnson P.E.-July, 2006

8-Solar Cell Lithium Ion Battery Charger Version 2Jim Wilber looked at my design for a battery charger and sent me some suggested changes.  He suggested using the LTC4412 ideal diode IC to switch off the current path from the solar cell to the battery in darkness.  He also noted that the 2.5v regulator from Seiko I had selected was no longer in production and suggested using the shunt reference. . . Circuit by David Johnson P.E.-May, 2013


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

10mhz to 20mhz Laser Light Detector -  This circuit was originally designed to detect laser light pulses for an optical Ethernet communications system.  It has good ambient light immunity. . . Circuit by David A. Johnson P.E.-June, 2000

10Mhz to 20Mhz Light Receiver -  Light power to volts conversion = APPROX.15mV per microwatt at 850nM. . . Circuit by David A. Johnson P.E.-July, 2006

12 Volt 10 Amp Dark Activated Switch (kit available) -  The DAS1 is a combination manual switch and automatic dark-activated switch.  It is designed to control up to 10 amps of 12V lights.  A pair of high-intensity white LEDs are included in the circuit for built-in lighting.  The circuit includes a low voltage disconnect circuit that prevents excessive battery discharge on battery operated systems.  The DAS1 is ideal for solar powered lighting systems, it can also be used for line powered and automotive/marine applications.  External 12V lights consisting of white LEDs, incandescent lamps and/or fluorescent lamps can be driven by the DAS1. __ Designed by G. Forrest Cook

12 Volt Lite/Dark Lamp Switch -  Often, for certain low voltage lighting systems; you would like to turn off the lights during the bright light of the day.  Most commercial day/night switches are designed for AC lighting.  The circuit below was designed for a 12v DC system.  But, it could be modified for other voltage as well.  It uses an inexpensive phototransistor as the light detector. . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2008

12V 10A Dark Activated Switch -  The DAS1 kit can be used to automatically turn on 12V lamps when it becomes dark.  It has an on-board switch for selecting Off, Always On and On-at-Dark    (Auto) operation.  The DAS1 can control up to 10 Amps of 12V DC lighting, it also includes two ultra-bright white LEDs for a low power self-contained light source.  The DAS1 is perfect for controlling external arrays of 12V white LED lamps, 12V fluorescent lamps and 12V incandescent lamps.  Use it for indoor/outdoor accent lighting, street lighting, security lights, automatic highway signs and more.   __ Designed by Solar Orbit Kit

12V 15A Low Voltage Disconnect -  The LVD1 kit is used for automatically controlling the power to 12V solar-powered battery-operated electronic devices.  It shuts down power when the battery voltage drops to a selected voltage, protecting the battery from damaging excessive discharge conditions.  Power is either automatically or manually reconnected at a selected voltage when the battery is recharged.  An adjustable low-voltage indicator warns of the impending power outage.  The low-voltage signal is externally available, allowing computers to monitor the condition and perform a graceful shutdown.  The low-voltage signal can also be used for triggering a variety of low-voltage warning systems. 
 __ Designed by Solar Orbit Kit

12V 20A Solar Charge Controller -  The SCC3 kit is the heart of a 12 Volt solar power system, it regulates the charging of batteries from photovoltaic    (PV) solar panels.  A charge controller is an essential part of any solar power system.  A 12 Volt solar power system can provide power to a wide variety of devices such as lighting systems, Ham and CB radios, car stereos, cell phone chargers, laptop computers, televisions, recording equipment, fans, water pumps and other 12V DC loads.  With the addition of a DC to AC inverter, the DC power can be converted to 120 Volts AC for running many household electronic devices. 
 __ Designed by G. Forrest Cook

12V 9A Solar Power Center -  The SPC3 kit contains all of the circuitry for a medium-sized solar power system.  It includes a solar charge controller for battery charge regulation, a smart on/off power switch with automatic low voltage disconnect operation and a built-in white LED lighting system.  Additional lights and other 12V devices can be connected to the load terminals and controlled by the SPC3.  The SPC3 can regulate up to 9 amps of incoming solar power and can switch an external load of up to 10 amps. __ Designed by Solar Orbit Kit

12V LED Battery Voltage Monitor -  The BVM1 kit can be used to monitor the voltage of a 12 Volt battery.  It features ten ultra-bright LEDs in five vivid colors for quick battery voltage measurement.  One of the LEDs will briefly blink on every 1.25 seconds, keeping average power consumption low.  The display is readable from dark to full sunlight.  A switch-controlled low voltage beeper is included, this provides a warning when the battery voltage drops below a preset value and can help to prevent excessive discharge.   __ Designed by Solar Orbit Kit

12v Light/Dark Lamp Switch -  At night, this circuit will route current to a 12v lamp, turning it on. . . Circuit by David A. Johnson P.E.-July, 2006

12v Touch Switch Exciter Circuit -  This circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits.    It can support a cable length of about 2500 feet.    A typical remote switch circuit is also shown as well as a receiver circuit for those switches.. . . Circuit by David A. Johnson P.E.-February, 2002

12v-24v AC & DC Day/Night Switch -  The circuit uses a bridge rectifier circuit to convert AC into DC.  A 12v zener diode limits the operating voltage of the circuit to 12v.  A tiny Schmitt trigger inverter and a phototransistor detects the ambient light intensity.  If there is sufficient light, the inverter disables a push-pull oscillator circuit . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2012

1Khz to Over 70Mhz Light Receiver -  This circuit uses one tiny C-MOS inverter IC to form a modulated light receiver with a very fast response.  It is designed around a PIN photo diode that is packaged for use with plastic optical fibers.  It can be used as an optical fiber receiver.  By using the open end of the optical fiber it can "sniff" out any modulated light signals . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

1us Light Pulse Receiver -  This circuit is designed to detect very weak light pulses lasting 1uS.  It uses a tuned LC feedback network to provide high sensitivity while giving high ambient light immunity.  A post voltage amplifier is included with a gain of about X20 . . . Hobby Circuit designed by David A. Johnson P.E.-March, 1999

1uS Light Pulse Receiver + Post Amp -  This circuit is designed to detect very weak light pulses lasting 1uS.  It uses a tuned LC feedback network to provide high sensitivity while giving high ambient light immunity.  A post voltage amplifier is included with a gain of about X20.  The circuit is described in more detail in the receiver section of my Handbook of Optical Through the Air Communications.    Note: The LF357 op amp is no longer available, this circuit is for reference only.. . . Circuit by David Johnson P.E.-March, 1999

1W White LED Night Light -  As many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components.  This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by David Johnson P.E.-November, 2008

20Mhz VCSEL 3mw Laser Test Circuit -  This circuit takes advantage of some new vertical cavity surface emitting lasers    (VCSEL) that donít require light output control circuits.  The circuit shows how to drive the device from a single high speed CMOS IC. . . Circuit by David A. Johnson P.E.-June, 2000

24 Volt Day Night Switch -  Many low voltage outdoor lighting systems use 24vac to power the devices.  The low voltage is much safer to use outside than standard 120vac or 240vac power systems.  The circuit below is designed to turn off power to outdoor lights during daylight and turn them back on at night . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2010

24-Bit ADC Measures from DC to Daylight -  DN219 Design Notes__ Linear Technology/Analog Devices

24v NiMH Battery Charger using a 12v Solar Panel  -  A while back I received an email from a guy in the UK.  He wanted to use a small solar panel, designed to charge 12v lead acid batteries, but use it to charge a 24v battery pack.  His 24v battery pack used 20 AA size NiMH cells.  He went on to explain that his 20 cell NiMH battery pack was used very infrequently . . . Hobby Circuit designed by David A. Johnson P.E.-October, 2011

2Mhz Broad Band Optical Fiber Receiver -  If you need more sensitivity than the above circuit this circuit provides about ten times more gain.  It too is designed around an inexpensive plastic optical fiber detector . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

30Khz Light Receiver Amp -  This circuit uses NPN darlington transistor to amplify the signal produced from short light flashes, as detected by a PIN photo diode.  The circuit draws only about 330uA from a 6v battery. . . Circuit by David Johnson P.E.-March, 2002

3mw Laser Test-20Mhz VCSE - L -  This circuit takes advantage of some new vertical cavity surface emitting lasers    (VCSEL) that donít require light output control circuits.  The circuit shows how to drive the device from a single high speed CMOS IC . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

4 in 1 Burglar Alarm -  In this circuit, the alarm will be switched on under the following four different conditions: 1.  When light falls on LDR1    (at the entry to the premises) .2.  When light falling on LDR2 is obstructed.3.  When door switches are opened or a wire is broken.4.  When a handle is touched.  The light dependent resistor LDR1 should be placed in darkness near the door lock or handle etc.  If an intruder flashes his torch __ Designed by Radioland.nt.au

40Khz Burst Laser Diode Driver -  Some laser tag or simulated combat games can use this circuit to send short bursts of modulated laser light at the opponent's vest, equipped with a matching light receiver.  The circuit operates from three 1.5v cells    (4.5v) that should provide enough energy . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

40Khz Laser Burst Detector -  This circuit was originally designed to detect weak flashed of laser light bounced off of a fabric video projection screen.  It was used as part of a firearm training system.  It generates a 100mS output pulse whenever it detects a 3ms to 5ms-laser burst,. . . Circuit by Dave Johnson P.E.-June, 2000

40Khz Light Detector with High Ambient Light Immunity -  This circuit is designed for detecting infrared light modulated at around 40KHz.  Itís feedback scheme cancels much of the DC component from ambient light.  Itís conversion factor is about 100 millivolts per microwatt of 900nm light.. . . Circuit by Dave Johnson P.E.-July, 2006

40KHz Light Receiver Front-End Circuit -  This circuit uses a unique cascode amplifier circuit to convert the current from a PIN photo diode to a current without any feedback network.  It is very stable and very sensitive.  This hobby circuit shown has the potential for a conversion factor of 10 volts per microwatt at 900nm.  I included a simple JFET post-amplifier with a gain of about 20.. . . Circuit by David Johnson P.E.-June, 2000

40KHz Modulated Light Detector -  If you want even more sensitivity than the above circuit, try this design.  When used with a one centimeter square photodiode, you can achieve a range of several hundred feet with a standard TV or VCR remote control module. . . Circuit by Dave Johnson P.E.-March, 1999

40khz TV-VCR Light Source Repeater -  This circuit is designed to be placed directly in front of a standard TV or VCR remote.  The exiting light pulses produced by the circuit match the pulses from the remote but are about 10 times more powerful.  Using the device, the remote can operate a TV or VCR over three times the normal distance. . . Circuit by David Johnson P.E.-June, 2000

50Mhz Broad Band Optical Fiber Receiver Version A -  If the above circuit it still too slow, you can try this circuit.  What it lacks in sensitivity it makes up for in speed.  The circuit attaches a plastic fiber optic PIN photodiode assembly to a small box containing a small 3v battery and a standard. . . Circuit by David A. Johnson P.E.-June, 2000

5Mhz Broad Band  Optical Fiber Receiver -  This circuit is a simple broad band light detector that uses a very inexpensive IC and a PIN photodiode that is packaged for use with plastic optical fibers.  It has a bandwidth from 1KHz to over 5MHz.  It is great for experimenting with various modulated. . . Circuit by Dave Johnson P.E.-June, 2000

6V to 24V DC Day/Night Switch -  Using an inexpensive phototransistor, this circuit switches 12v to 24v power to a load, whenever the sun goes down. . . Circuit by David Johnson P.E.-July, 2006

8-Solar Cell Lithium Ion Battery Charger Version 2 -  Jim Wilber looked at my design for a battery charger and sent me some suggested changes.  He suggested using the LTC4412 ideal diode IC to switch off the current path from the solar cell to the battery in darkness.  He also noted that the 2.5v regulator from Seiko I had selected was no longer in production and suggested using the shunt reference. . . Circuit by David Johnson P.E.-May, 2013

   >>>

Light Dependent Circuits:  #'s - D      E - L      M- Z

 


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


Discovercircuits.com endeavors to credit original designers.   Please alert us by eMail so we can
delete links to material that have been copied without your permission
.   Thank you.


© Copyright of all original material on this website is the property
of David A. Johnson, P.E. (Dave Johnson & Associates ) unless otherwise noted.  

Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.
All material is provided "as is" without guarantees or warranty of any kind, either expressed or implied.