I just designed a Variable Voltage Regulator for 0 to 10V dc.
For tht I used a LM7812 with about 17V as the input and I get 12V at output.
Now, to regulate the 12V o/p dc, I connected a Voltage Divider ckt with a Potentiometer.
The pot is of 600Kohms and so I connnected a 120kOhms resistor in series to get the voltage divider output to 10v.
Now at no load, everytime I move my pot, the output varies from 0v to 10v. but immediately as I connect a load (which is a standard Dimmable Balast for tubelights which takes 1-10v as input), the output voltage goes to 11.5v and on turning the pot, I dont get a linear response.
The output remains at 11.5v for a long time and only after the resistance of the pot has decreased to less than 300kohms that the output starts reducing, but its not gradual and shows a exponential format...
Am very confused on y is this happening??? Load rating of the dimmable ballast is 1-10v, less than 0.6mA.
I know that this is not the ideal way to create a voltage regulator... but still am confused as to wat is the problem...
Also suggest me a better way to make a 0-10v regulator please.
Thanks
For tht I used a LM7812 with about 17V as the input and I get 12V at output.
Now, to regulate the 12V o/p dc, I connected a Voltage Divider ckt with a Potentiometer.
The pot is of 600Kohms and so I connnected a 120kOhms resistor in series to get the voltage divider output to 10v.
Now at no load, everytime I move my pot, the output varies from 0v to 10v. but immediately as I connect a load (which is a standard Dimmable Balast for tubelights which takes 1-10v as input), the output voltage goes to 11.5v and on turning the pot, I dont get a linear response.
The output remains at 11.5v for a long time and only after the resistance of the pot has decreased to less than 300kohms that the output starts reducing, but its not gradual and shows a exponential format...
Am very confused on y is this happening??? Load rating of the dimmable ballast is 1-10v, less than 0.6mA.
I know that this is not the ideal way to create a voltage regulator... but still am confused as to wat is the problem...
Also suggest me a better way to make a 0-10v regulator please.
Thanks