StudentSA
Member
Hi.
I have a circuit which uses the LM3914 as a Voltage level meter. I would like to be able to vary the brightness of the LED`s using a circuit as attached.
Pins 7 and 8 (REF OUT and REF ADJ) of the LM3914 has a constant voltage source of 1.25V. According to the datasheet the amount of current drawn from this pin is proportional(10x) to the LED brightness.
With this in mind I would like my signal of 0-10V (V2 in schematic) to cause a current of 0 - 1mA (i.e. through R2) to be drawn out of the 1.25V source.
Is this ciruit idea correct and how will I choose the values of the resistors?
![Dimmer.Jpeg Dimmer.Jpeg](https://www.electro-tech-online.com/data/attachments/38/38704-9a1a7fb849a72fb5e69f14feac32eefa.jpg)
Any advise is appreciated.
Regards,
StudentSA
I have a circuit which uses the LM3914 as a Voltage level meter. I would like to be able to vary the brightness of the LED`s using a circuit as attached.
Pins 7 and 8 (REF OUT and REF ADJ) of the LM3914 has a constant voltage source of 1.25V. According to the datasheet the amount of current drawn from this pin is proportional(10x) to the LED brightness.
With this in mind I would like my signal of 0-10V (V2 in schematic) to cause a current of 0 - 1mA (i.e. through R2) to be drawn out of the 1.25V source.
Is this ciruit idea correct and how will I choose the values of the resistors?
![Dimmer.Jpeg Dimmer.Jpeg](https://www.electro-tech-online.com/data/attachments/38/38704-9a1a7fb849a72fb5e69f14feac32eefa.jpg)
Any advise is appreciated.
Regards,
StudentSA