• Solar Insulation Monitor -  Owners of photovoltaic solar panels often like to monitor how bright the sunshine is. They can use this information to gage how well their solar panels are doing. On a typical clear day, the sun energy at sea level is about 1000 watts per square meter . . . [Hobby Circuit designed by David Johnson P.E.,  05/01/12]

• Solar Lithium Ion Battery Charger Using LT1129 -  I have been designing a number of solar powered devices lately. Many of them use just a single 3.6v lithium ion battery. These batteries like to be charged from a fixed 4. 2v source with a charging current limited to about C/8, where C is the milliamp-hour rating of the part . . . [Circuit by Dave Johnson P.E.,  12/30/12]

• Solar Path Light Improvement -  Use the circuit below was designed to replace the guts of an existing path light assembly with one which has a much better performance. I suggest using a quality 10 cell solar panel with at least a 4 square inch area. Buy a panel with solar panels that . . . [Circuit by David Johnson P.E.,  03/13/11]

• Solar Powered Cell Phone Charger -  The simple circuit below regulates the voltage from a 6v solar panel to a fixed +5v. That voltage can be fed to any cell phone or USB connected portable device, to charge its battery. The circuit uses a Reg113-5 voltage regulator from Texas Instruments . . . [Circuit by David Johnson P.E.,  01/02/11]

• Solar Powered Flood Light Using NiMH Cells -  There are many solar powered garden lights available. Most of the devices offered at the home improvement stores have very poor performance. Their batteries are too small, the light launched is weak and the solar panels are undersized. None of the devices I have tested would operate through a typical night . . . [Circuit by David Johnson P.E.,  12/20/13]

• Solar Powered Infrared 1W Security Camera Illuminator -  Many security cameras are equipped with an array of infrared LEDs to illuminate an area in front of the camera with invisible light for night time surveillance.   However, there are times when a remote area, well away from the camera, needs additional infrared light.   The circuit below uses a modified solar powered path light to bathe a fairly large area with 850nm infrared light . . . [Circuit by David Johnson P.E.,  06/22/14]

• Solar Powered Lithium Ion Battery Charger -  The circuit below feeds a controlled current and voltage to a 3.6v lithium ion battery. The current is limited to 300ma and the voltage is limited to 4. 2 volts. The circuit uses a LTC1734 IC from Linear Technology. No diode is needed between the circuit a . . . [Hobby Circuit designed by David A. Johnson P.E.,  05/15/07]

• Solar PV Cell Test Fixture -  This is an illustration of a test fixture, which can be used to test individual solar cells for short circuit current. Using a PIN photo diode and a control circuit, the solar cells can be tested under constant light level conditions . . . [Circuit by David Johnson P.E.,  10/01/06]

• Solar-Powered Pump Motor Controller -  A Discover visitor had a problem. He needed a simple on/off controller for his solar powered water pump. His system used two 12v 50 watt solar panels wired in series. The power from the solar panels drove a submerged water pump. However, during . . . [Circuit by David A. Johnson P.E.,  10/03/10]

• Time to Dust Indicator -  I thought about this circuit when I heard that a lot cleaning personal in hotels were either dusting rooms more often than necessary or not enough. I have not yet built and tested this circuit completely but in concept it should work . . . [Circuit by David A. Johnson P.E.,  06/06/00]

• Transmitter for Line Powered Xenon Flash -  This line powered xenon flash circuit drives a small camera type flash tube. It has an optical isolator to allow the flash to be safely triggered from some remote device. A flash rate of 2Hz is possible with the circuit . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/09/00]

• TV-VCR Light Source 40Khz 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 . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/04/00]

• Ultra Low Power detects Clear Fluid -  Using an ultra low power technique, this circuit detects when a clear fluid is inside a piece of clear plastic tubing. It can be used for fluid level control and monitoring . . . [Hobby Circuit designed by David A. Johnson P.E.,  10/22/05]

• Use Color Film Negative to Make An Optical Filter -  This isn’t an electronic circuit but the file shows the curve for an optical filter made from exposed color film. The material blocks most visible light but is very transparent to 880nM infrared light. Kodak 100ASA is exposed to "cool white" fluorescent light for about 5 seconds . . . [Hobby Circuit designed by Dave Johnson P.E.,  01/01/98]

• Variable Isolated AC Voltage Spans 0Vac to 280Vac -  I designed and built this circuit about 25 years ago. It came in handy for many projects that were powered from 120 VAC, 240 VAC and 277 VAC. It provides complete isolation from the power line. It uses two 1:1 isolation transformers that are wired in parallel . . . [Circuit by Dave Johnson P.E.,  07/09/00]

• Water Pump controlled by Solar Power -  A Discover Circuits visitor had a problem. He needed a simple on/off controller for his solar powered water pump. His system used two 12v 50 watt solar panels wired in series. The power from the solar panels drove a submerged water pump. However, during . . . [Hobby Circuit designed by Dave Johnson P.E.,  10/03/10]

• Xenon Flash Receiver-Pg2 -  This is Page 2 of the receiver circuit AIR TRANSPARENCY MONITOR, XENON FLASH RECEIVER . . . [Hobby Circuit designed by David A. Johnson P.E.,  06/17/00]

• Xenon Lamp Flash Detector Amplifier -  This circuit has a very low standby current requirement yet has very high sensitivity toward the light flashes from a xenon lamp. When connected to a flip/flop it can serve as an on on/off Controller . . . [Circuit by David A. Johnson P.E.,  12/14/04]

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

Solar Insulation Monitor -  Owners of photovoltaic solar panels often like to monitor how bright the sunshine is. They can use this information to gage how well their solar panels are doing. On a typical clear day, the sun energy at sea level is about 1000 watts per square meter . . . [Hobby Circuit designed by David Johnson P.E.,  05/01/12]

Solar Lithium Ion Battery Charger Using LT1129 -  I have been designing a number of solar powered devices lately. Many of them use just a single 3.6v lithium ion battery. These batteries like to be charged from a fixed 4. 2v source with a charging current limited to about C/8, where C is the milliamp-hour rating of the part . . . [Circuit by Dave Johnson P.E.,  12/30/12]

Solar Path Light Improvement -  Use the circuit below was designed to replace the guts of an existing path light assembly with one which has a much better performance. I suggest using a quality 10 cell solar panel with at least a 4 square inch area. Buy a panel with solar panels that . . . [Circuit by David Johnson P.E.,  03/13/11]

Solar Powered Cell Phone Charger -  The simple circuit below regulates the voltage from a 6v solar panel to a fixed +5v. That voltage can be fed to any cell phone or USB connected portable device, to charge its battery. The circuit uses a Reg113-5 voltage regulator from Texas Instruments . . . [Circuit by David Johnson P.E.,  01/02/11]

Solar Powered Flood Light Using NiMH Cells -  There are many solar powered garden lights available. Most of the devices offered at the home improvement stores have very poor performance. Their batteries are too small, the light launched is weak and the solar panels are undersized. None of the devices I have tested would operate through a typical night . . . [Circuit by David Johnson P.E.,  12/20/13]

Solar Powered Infrared 1W Security Camera Illuminator -  Many security cameras are equipped with an array of infrared LEDs to illuminate an area in front of the camera with invisible light for night time surveillance.   However, there are times when a remote area, well away from the camera, needs additional infrared light.   The circuit below uses a modified solar powered path light to bathe a fairly large area with 850nm infrared light . . . [Circuit by David Johnson P.E.,  06/22/14]

Solar Powered Lithium Ion Battery Charger -  The circuit below feeds a controlled current and voltage to a 3.6v lithium ion battery. The current is limited to 300ma and the voltage is limited to 4. 2 volts. The circuit uses a LTC1734 IC from Linear Technology. No diode is needed between the circuit a . . . [Hobby Circuit designed by David A. Johnson P.E.,  05/15/07]

Solar PV Cell Test Fixture -  This is an illustration of a test fixture, which can be used to test individual solar cells for short circuit current. Using a PIN photo diode and a control circuit, the solar cells can be tested under constant light level conditions . . . [Circuit by David Johnson P.E.,  10/01/06]

Solar-Powered Pump Motor Controller -  A Discover Circuits visitor had a problem. He needed a simple on/off controller for his solar powered water pump. His system used two 12v 50 watt solar panels wired in series. The power from the solar panels drove a submerged water pump. However, during . . . [Circuit by David A. Johnson P.E.,  10/03/10]

Sunrise Lamp using 120VAC 60 Watt Lamp -  In this circuit, a 120VAC lamp is slowly illuminated over a approximate 20 minute period. The bridge rectifier supplies 120 DC to the MOSFET and 60 watt lamp. A 6. 2K, 5 watt resistor and zener diode is used to drop the voltage to 12 volts DC for the circuit power. The bridge rectifier should be rated at 200 volts and. . .  [Bill Bowden's circuit]

Sunset Lamp -  LDR-based automatic lights flicker due to the change in light intensity at dawn and dusk. So compact fluorescent lamps (CFLs) are unsuitable in such circuits as flickering may damage the electronic circuits within these lamps. The circuit described here can solve the problem and switch on the lamp instantly when the light intensity decreases below a preset level. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

Sun-Up Alarm -  The Sun - Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on. It can also be used to detect a light beam, headlights etc. The circuit works as follows. The phototransistor is very sensitive to light. (Any phototransistor will work fine) . . . 

Time to Dust Indicator -  I thought about this circuit when I heard that a lot cleaning personal in hotels were either dusting rooms more often than necessary or not enough. I have not yet built and tested this circuit completely but in concept it should work . . . [Circuit by David A. Johnson P.E.,  06/06/00]

Transmitter for Line Powered Xenon Flash -  This line powered xenon flash circuit drives a small camera type flash tube. It has an optical isolator to allow the flash to be safely triggered from some remote device. A flash rate of 2Hz is possible with the circuit . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/09/00]

TV-VCR Light Source 40Khz 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 . . . [Hobby Circuit designed by Dave Johnson P.E.,  06/04/00]

Twilight Lamp Blinker -  During sunset or sunrise, the ambient light is not adequate to lead you through the open doorway or make your way around obstructions. To avoid any mishap, here is a twilight lamp blinker that you can place near obstructions. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

Twi-light using white LEDs -  This sunlight-controlled lamp uses a light-dependent resistor (LDR) as the sunlight sensor and a total of 25 high-brightness white LEDs. Separate resistors are connected in series with each row of the LEDs. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

Ultra Low Power detects Clear Fluid -  Using an ultra low power technique, this circuit detects when a clear fluid is inside a piece of clear plastic tubing. It can be used for fluid level control and monitoring . . . [Hobby Circuit designed by David A. Johnson P.E.,  10/22/05]

Use Color Film Negative to Make An Optical Filter -  This isn’t an electronic circuit but the file shows the curve for an optical filter made from exposed color film. The material blocks most visible light but is very transparent to 880nM infrared light. Kodak 100ASA is exposed to "cool white" fluorescent light for about 5 seconds . . . [Hobby Circuit designed by Dave Johnson P.E.,  01/01/98]

Variable Isolated AC Voltage Spans 0Vac to 280Vac -  I designed and built this circuit about 25 years ago. It came in handy for many projects that were powered from 120 VAC, 240 VAC and 277 VAC. It provides complete isolation from the power line. It uses two 1:1 isolation transformers that are wired in parallel . . . [Circuit by Dave Johnson P.E.,  07/09/00]

Water Pump controlled by Solar Power -  A Discover Circuits visitor had a problem. He needed a simple on/off controller for his solar powered water pump. His system used two 12v 50 watt solar panels wired in series. The power from the solar panels drove a submerged water pump. However, during . . . [Hobby Circuit designed by Dave Johnson P.E.,  10/03/10]

Xenon Flash Receiver-Pg2 -  This is Page 2 of the receiver circuit AIR TRANSPARENCY MONITOR, XENON FLASH RECEIVER . . . [Hobby Circuit designed by David A. Johnson P.E.,  06/17/00]

Xenon Lamp Flash Detector Amplifier -  This circuit has a very low standby current requirement yet has very high sensitivity toward the light flashes from a xenon lamp. When connected to a flip/flop it can serve as an on on/off Controller . . . [Circuit by David A. Johnson P.E.,  12/14/04]

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