Joule Thief Transformer Physical Design For LED Lighting https://explore.partquest.com/node/156256 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/156256"></iframe> Title Description <p>This simple "Joule Thief" self-oscillating LED circuit will produce light even when the battery voltage drops to 0.4 V. Of course the light will dim as the voltage drops, since there is no current regulation. The design is based on an example circuit from Wikipedia: https://en.wikipedia.org/wiki/Joule_thief</p><p>For the transformer physical design, the user can explore different magnetic toroid core sizes, material types, number of winding turns, etc., to see their impact on the LED performance. This "virtual design" test-bench is particularly useful to view core saturation and its current limiting affect in this particular circuit. For example, try using a smaller core with 1/5th the area and length of the original.</p> About text formats Tags Joule ThiefLEDoscilatortransformer saturation Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
Transient Stability Testing of Transmission Line Fed LED Driver https://explore.partquest.com/node/141851 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/141851"></iframe> Title Description <p>This is a companion example to the design: "TDFS Impedance Stability of Transmission Line Fed LED Driver - Switching". In this version, a switch is added to turn on two of the LEDs after 2 ms, to inject a load transient into the system. This transient will expose the severity of the damped ringing response at the converter input, or system instability if the source/load impedance ratio is inadequate.</p><p>The initial configuration for this design uses a cable length of 400 meters with 8 AWG = 2.1 mOhm/meter conductors, and a converter input capacitor = 22uF. This is consistent with the companion design. You can try using an increased cable length (e.g. 800 meters, 5 AWG = 1 mOhm/meter) by making a copy of this design and re-running the simulation. You will see that the circuit becomes unstable at that longer length. You can also try larger values of input capacitance, to mitigate the instability problem.</p> About text formats Tags Buck ConverterConstant Power LoadsSwitching ConverterLEDtransmission lineStep-DownTDFS Impedance Stability Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
TDFS Impedance Stability of Transmission Line Fed LED Driver - Switching https://explore.partquest.com/node/136831 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/136831"></iframe> Title Description <p>This example demonstrates the use of the TDFS method (Time Domain Frequency Sweep) to measure impedance stability ratio. The system is a switching DC/DC step-down power converter used for LED lighting, supplied by a battery through a long power cable.</p><p>The TDFS impedance stability measurement model applies a 0.2A sinusoidal stimulus current at the point where the cable connects to the converter. The voltage at that point, as well as the stimulus current splits (toward the source and the load) are measured, and the associated source and load impedances vs. frequency are computed.</p><p>The ratio of the source to load impedance is the impedance stability ratio (Tm). Similar to the open-loop frequency response requirement for closed-loop stability, Tm must not have magnitude = 1.0 at phase = 180 degrees, at any frequency.</p><p>For this system, with a cable length of 400 meters and 8 AWG wire, the results show that the impedance ratio magnitude (green waveform) reaches unity (0 dB) at close to 2 kHz, where the phase (light blue waveform) is approximately 165 degress. This implies a "phase margin" of only 15 degrees, For a longer cable, this margin is further reduced. As shown in the companion example, "Transmission Line Fed LED Driver - Switching", for the cable length = 800 meters the system is unstable.</p><p>This instability is the result of the "source" impedance (which includes the cable) variation over frequency, interacting with the varying load impedance. Note that at low frequency, the load effectively has a negative impedance, due to the constant power nature of the DC to DC converter.</p> About text formats Tags Buck ConverterConstant Power LoadsSwitching ConverterLEDtransmission lineStep-DownTDFS Impedance Stability Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
LED Dimmer Circuit using 555 Timer https://explore.partquest.com/node/105211 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/105211"></iframe> Title Description <p>This LED Dimmer Circuit uses a 555 Timer to control the PWM duty cycle of the current drive. Rather than apply proportional but continuous current to the LED for dimming, which can cause color shifts, modulating the duty cycle allows the LED to operate at its nominal current during the “ON” portion of the cycle. Because the frequency response of human vision is limited, using a PWM frequency of 250 Hz avoids the perception of flicker for the observer.</p> <p>The LED model has an internal monitor for the "perceived" light output (blue waveform), which is a low-pass filtered version of the instantaneous light output. The filter pole frequency is set to 15 Hz to represent the bandwidth of the human eye. The value of the dimmer setting (green waveform) is increased from 10% to 90% at time 100msec. The LED current pulses (red waveform) are shown before and after the duty-cycle transition.</p> <p>Part of this design is based on a dimmer schematic found on-line:</p> <p><a href="http://www.555-timer-circuits.com/led-dimmer.html">http://www.555-timer-circuits.com/led-dimmer.html</a></p> <p>That original circuit is actually incorrect, one of the diodes connected to pin 7 on the 555-Timer needs to be reversed. There was a comment from a reader who said he built the circuit as shown and it didn’t work. This is a good example of the value of simulating circuits before building hardware!</p> About text formats Tags 555 TimerLEDpotentiometer Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
Copy of Transient Stability Testing of Transmission Line Fed LED Driver - on Fri, 11/28/2025 - 14:51 Designer249130 × Member for 2 years 3 months 25 designs 1 groups Welcome to the community!! https://explore.partquest.com/node/701047 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/701047"></iframe> Title Description <p>This is a companion example to the design: "TDFS Impedance Stability of Transmission Line Fed LED Driver - Switching". In this version, a switch is added to turn on two of the LEDs after 2 ms, to inject a load transient into the system. This transient will expose the severity of the damped ringing response at the converter input, or system instability if the source/load impedance ratio is inadequate.</p><p>The initial configuration for this design uses a cable length of 400 meters with 8 AWG = 2.1 mOhm/meter conductors, and a converter input capacitor = 22uF. This is consistent with the companion design. You can try using an increased cable length (e.g. 800 meters, 5 AWG = 1 mOhm/meter) by making a copy of this design and re-running the simulation. You will see that the circuit becomes unstable at that longer length. You can also try larger values of input capacitance, to mitigate the instability problem.</p> About text formats Tags Buck ConverterConstant Power LoadsSwitching ConverterLEDtransmission lineStep-DownTDFS Impedance Stability Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
LED Dimmer Circuit using 555 Timer Designer263365 × Member for 3 months 1 week 44 designs 2 groups Welcome to the community!! https://explore.partquest.com/node/700679 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/700679"></iframe> Title Description <p>This LED Dimmer Circuit uses a 555 Timer to control the PWM duty cycle of the current drive. Rather than apply proportional but continuous current to the LED for dimming, which can cause color shifts, modulating the duty cycle allows the LED to operate at its nominal current during the “ON” portion of the cycle. Because the frequency response of human vision is limited, using a PWM frequency of 250 Hz avoids the perception of flicker for the observer.</p><p>The LED model has an internal monitor for the "perceived" light output (blue waveform), which is a low-pass filtered version of the instantaneous light output. The filter pole frequency is set to 15 Hz to represent the bandwidth of the human eye. The value of the dimmer setting (green waveform) is increased from 10% to 90% at time 100msec. The LED current pulses (red waveform) are shown before and after the duty-cycle transition.</p><p>Part of this design is based on a dimmer schematic found on-line:</p><p><a href="http://www.555-timer-circuits.com/led-dimmer.html">http://www.555-timer-circuits.com/led-dimmer.html</a></p><p>That original circuit is actually incorrect, one of the diodes connected to pin 7 on the 555-Timer needs to be reversed. There was a comment from a reader who said he built the circuit as shown and it didn’t work. This is a good example of the value of simulating circuits before building hardware!</p> About text formats Tags 555 TimerLEDpotentiometer Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
Copy of Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Thu, 10/09/2025 - 17:35 Designer248415 × Member for 2 years 3 months 23 designs 4 groups Welcome to the community!! https://explore.partquest.com/node/697895 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/697895"></iframe> Title Description <p>This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.</p><p>In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.</p><p>The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.</p> About text formats Tags LEDelectro-thermalNTCThermistorVISHAY Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
Copy of Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Thu, 10/09/2025 - 15:23 Designer248415 × Member for 2 years 3 months 23 designs 4 groups Welcome to the community!! https://explore.partquest.com/node/697886 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/697886"></iframe> Title Description <p>This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.</p><p>In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.</p><p>The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.</p> About text formats Tags LEDelectro-thermalNTCThermistorVISHAY Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
Copy of Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Thu, 10/09/2025 - 18:19 Designer244519 × Member for 3 years 1 month 10 designs 1 groups I'm a member of the PartQuest Explore community. https://explore.partquest.com/node/697883 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/697883"></iframe> Title Description <p>This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.</p><p>In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.</p><p>The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.</p> About text formats Tags LEDelectro-thermalNTCThermistorVISHAY Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
Copy of Analog LED Driver with Thermal Protection using FloTHERM Netlist - on Thu, 10/09/2025 - 18:01 Designer244519 × Member for 3 years 1 month 10 designs 1 groups I'm a member of the PartQuest Explore community. https://explore.partquest.com/node/697880 <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/697880"></iframe> Title Description <p>This LED spotlight example demonstrates the value of simulating both the electrical and thermal aspects of power dissipating circuits together, simultaneously.</p><p>In this design, a Vishay NTCLE100 Thermistor is used in a detection circuit to monitor the enclosure temperature. It is used for thermal shut-down protection, to keep the enclosure temperature well below the "Tg" (glass transition temperature) of the spotlight's Nylon 6 polymer lens. This is particularly helpful when operating at higher external ambient temperatures.</p><p>The "Thermals" (thermal dynamics) model was automatically generated from a full 3D-CFD analysis of the spotlight board layout and enclosure, using FloTHERM. The model is in the IEEE Standard VHDL-AMS format, so it can be directly imported into the SystemVision "1D" circuit and system simulation context. The ability to include an accurate model of the thermal environment is key to having "thermally-aware" circuit function design and board layout processes.</p> About text formats Tags LEDelectro-thermalNTCThermistorVISHAY Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None -
