I have the module “K8064” and actually it works, but can I adjust the control voltage by e.g. changing some resistors, to 0-4.7V instead of 0-5V?
The module is designed in original for a control voltage of 0-5 V (max.
0-12V).
Because my available control voltage is not quite 5V, rather only max.
4.7V,
it is not possible for me to bring the output power to 100% with that voltage.
Even if RV2 is fully turned counterclockwise, the green LED is not glowing constantly, it still only flashes.
4.7V is the problem! The green LED will stop flashing only at min. 5.31V.
With the 2 trimpotentiometers it is not possible to adjust the brightness to the max. of 98% with 4.7V.
the problem could be after the optocoupler. First you must be sure of the power supply on the PIC controller.
You can measure this between pin 1 & 14. (must be around 5V).
ATTENTION: Every part is under high voltage !!!
Normally, analog IN on the PIC is max 4,85V.
You can boost this by removing R19 and replaced this with a ‘jumpwire’.
[quote]…First you must be sure of the power supply on the PIC controller.
You can measure this between pin 1 & 14. (must be around 5V).[/quote] Yes, the voltage between pin 1 & 14 is 5V.
Now I have found out that the real problem is the too small dynamic range, which results from the control voltage of 0-4,7V at Pin 9 (PIC).
To switch the lamp to 0%, the voltage at Pin 9 must be less than 2,46V.
To turn it on 98%, the voltage at Pin 9 must be min. 4,32V.
This results in a required minimum range at Pin 9 of 2,46-4,32V (difference: 1,86V).
With a control voltage of 0-4,7V this area is not completely covered.
The range that results from this control voltage is, depending on the potentiometer settings, 2,89-4,32V or 2,46-3,91V (difference: only 1,43V !!!)
Therefore the brightness can not be controlled over the full range!
Now the question is, how can I achieve the minimum range at pin 9 with the control voltage of 0-4,7V?
I think the combination of the resistors R18 and R19 must be another. But I am not sure.
Or maybe other values for R11 and R12??
I have a very similar problem, but I need to control it with a maximum of 3.3V, as opposed to Mark’s 4.7V. Could anyone please recommend a resistor to use in place of R16? Thank you.