Has anyone actually tried using a current source based on digital potentiometer to drive a LDR attenuator? I've seen it mentioned in the massive Lightspeed thread but has anyone actually tried it?
It would be good for folks who want an LDR based attenuator with digital control (for remote control, displays, integration etc).
Is this how the DIY Paradise Eva works?
Anyway, I was looking at this app note from Maxim which shows pretty much the generic current source based on a digital potentiometer and a shunt:
Precision Current Source is Software-Programmable - Maxim
I want to try it but use a regulated PSU instead of the shunt IC. By using their forumula Rsense should be 200R when using a 5V supply, but I'm not sure what to use for Rs? Can anyone explain what this resistor is for? I'm thinking its to limit the amount of current going through the digital potentiometer wiper as they can generally only handle 1mA...
It would be good for folks who want an LDR based attenuator with digital control (for remote control, displays, integration etc).
Is this how the DIY Paradise Eva works?
Anyway, I was looking at this app note from Maxim which shows pretty much the generic current source based on a digital potentiometer and a shunt:
Precision Current Source is Software-Programmable - Maxim
An externally hosted image should be here but it was not working when we last tested it.
I want to try it but use a regulated PSU instead of the shunt IC. By using their forumula Rsense should be 200R when using a 5V supply, but I'm not sure what to use for Rs? Can anyone explain what this resistor is for? I'm thinking its to limit the amount of current going through the digital potentiometer wiper as they can generally only handle 1mA...
Almost the same concept but less complicate and does not use as many i.c.s. 
Has anyone actually tried using a current source based on digital potentiometer to drive a LDR attenuator? I've seen it mentioned in the massive Lightspeed thread but has anyone actually tried it?
It would be good for folks who want an LDR based attenuator with digital control (for remote control, displays, integration etc).
Is this how the DIY Paradise Eva works?
Anyway, I was looking at this app note from Maxim which shows pretty much the generic current source based on a digital potentiometer and a shunt:
Precision Current Source is Software-Programmable - Maxim
I want to try it but use a regulated PSU instead of the shunt IC. By using their forumula Rsense should be 200R when using a 5V supply, but I'm not sure what to use for Rs? Can anyone explain what this resistor is for? I'm thinking its to limit the amount of current going through the digital potentiometer wiper as they can generally only handle 1mA...
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