Hey guys,
i want the k8055 multiplier range to be x2.
as per the formula multiplier=1+R10/R8
now the default r10 resistor is 10k. so that means r8 should be 10k as well for an x2 multiplier. however when i do this the range is not correct.
.092-2.6 volts on the inpuit only gives me a scale of 0-31 on the analog input when with a multiplier of x2 it should be the full range up to 255.
any ideas as to what is going on? thanks for any help.
The trimpot ATT1 must be adjusted to max position clockwise to get the full range.
ahhh! thankyou.
I also have a problem with the Analog in, when I adjust the onboard trim to max I find that my input jumps around, I have tried this with A1 and A2. If I back them off a small amount they become more stable only fluctuating 1 bit or sometimes nil, should I use a small capasitor to filter this? or can I remove this pot from the board or bypass it?
If you just bypass the trimpot then in the test mode (SK2 or SK3 jumper installed) you may short circuit the USB supply voltage by turning the trimpot to minimum position.
More safe way is to remove the trimpot and bypass it with a wire.
To avoid the input from floating, you have to add a pull down resistor (100k…1M) between the analog input and GND.