potentiometer

Application Area

bielikma
Designer230768

bielikma

Member for

4 years 7 months

3

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Description

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.

The LED model has an internal monitor for the "perceived" light output (light-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 (purple waveform) are shown just before and after the duty-cycle transition.

Part of this design is based on a dimmer schematic found on-line:

http://www.555-timer-circuits.com/led-dimmer.html

That original circuit is actually incorrect, one of the diodes 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!

About text formats

Copy of LED Dimmer Circuit using 555 Timer - on Sun, 03/01/2020 - 11:40

sandipxresta
Designer230022

sandipxresta

Member for

4 years 8 months

5

designs

1

groups

an electrical and electronic engineer

Description

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.

The LED model has an internal monitor for the "perceived" light output (light-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 (purple waveform) are shown just before and after the duty-cycle transition.

Part of this design is based on a dimmer schematic found on-line:

http://www.555-timer-circuits.com/led-dimmer.html

That original circuit is actually incorrect, one of the diodes 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!

About text formats

Copy of LED Dimmer Circuit using 555 Timer - on Sun, 02/23/2020 - 22:11

jpelectronica
Designer229914

jpelectronica

Member for

4 years 9 months

1

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Description

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.

The LED model has an internal monitor for the "perceived" light output (light-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 (purple waveform) are shown just before and after the duty-cycle transition.

Part of this design is based on a dimmer schematic found on-line:

http://www.555-timer-circuits.com/led-dimmer.html

That original circuit is actually incorrect, one of the diodes 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!

About text formats

Copy of LED Dimmer Circuit using 555 Timer - on Sat, 02/22/2020 - 20:10

Pearpleberry
Designer229895

Pearpleberry

Member for

4 years 9 months

2

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Description

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.

The LED model has an internal monitor for the "perceived" light output (light-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 (purple waveform) are shown just before and after the duty-cycle transition.

Part of this design is based on a dimmer schematic found on-line:

http://www.555-timer-circuits.com/led-dimmer.html

That original circuit is actually incorrect, one of the diodes 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!

About text formats

LED Dimmer Circuit

Shane_1
Designer165106

Shane_1

Member for

6 years 11 months

1

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Description

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. The LED model has an internal monitor for the "perceived" light output (light-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 (purple waveform) are shown just before and after the duty-cycle transition.Part of this design is based on a dimmer schematic found on-line: http://www.555-timer-circuits.com/led-dimmer.html That original circuit is actually incorrect, one of the diodes 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!

About text formats

JulioCsar
Designer139011

JulioCsar

Member for

7 years 3 months

1

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Test potentiometers

Mike Donnelly
Designer19

Mike Donnelly

Member for

11 years

1,697

designs

10

groups

Member of the PartQuest Explore Development Team. Focused on modeling and simulation of analog, mixed-signal and multi-discipline systems covering a broad range of applications, including power electronics, controls and mechatronic systems.

LED Dimmer Circuit

JohnGoor
Designer98876

JohnGoor

Member for

7 years 10 months

1

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Description

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. The LED model has an internal monitor for the "perceived" light output (light-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 (purple waveform) are shown just before and after the duty-cycle transition.Part of this design is based on a dimmer schematic found on-line: http://www.555-timer-circuits.com/led-dimmer.html That original circuit is actually incorrect, one of the diodes 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!

About text formats

LED Dimmer Circuit

CaesarB
Designer89066

CaesarB

Member for

7 years 11 months

3

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Description

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. The LED model has an internal monitor for the "perceived" light output (light-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 (purple waveform) are shown just before and after the duty-cycle transition.Part of this design is based on a dimmer schematic found on-line: http://www.555-timer-circuits.com/led-dimmer.html That original circuit is actually incorrect, one of the diodes 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!

About text formats

Voltage divider circuit using potentiometer

AAC
Designer78611

AAC

Member for

8 years 1 month

3

designs

1

groups

Add a bio to your profile to share information about yourself with other SystemVision users.

Terms of Use Cookie Notice Data Privacy Notice

bielikmaDesigner230768

Member for

sandipxrestaDesigner230022

Member for

jpelectronicaDesigner229914

Member for

PearpleberryDesigner229895

Member for

Shane_1Designer165106

Member for

JulioCsarDesigner139011

Member for

Mike DonnellyDesigner19

Member for

JohnGoorDesigner98876

Member for

CaesarBDesigner89066

Member for

AACDesigner78611

Member for

bielikma
Designer230768

sandipxresta
Designer230022

jpelectronica
Designer229914

Pearpleberry
Designer229895

Shane_1
Designer165106

JulioCsar
Designer139011

Mike Donnelly
Designer19

JohnGoor
Designer98876

CaesarB
Designer89066

AAC
Designer78611