Velleman projects K8055N Assembly instructions - Manual (Page 9)

9
Mount the rubber feet on the solder side of the PCB, see fig 1.0.
19. Rubber feet
Fig. 1.0
Construction
The analogue inputs A1 and A2 have a standard range of 0 ~ +5Vdc. To use them externally, remove the
jumper caps on SK2 and SK3. The internal 5V voltage source can only be used for testing purposes. When
the input voltage is too low you can amplify it x4 / x15.
A gain of x4 requires a resistance of 3K3 for R53 (input signal 1) and for R54 (input signal 2). A x15 gain
requires a resistance of 820ohm.
When the gain is set to e.g. x4, the max. input voltage falls inversely proportional to 1,25V.
If you want a different gain factor you can calculate it quite easily using the following formula :
Gain A1 = 1 + (R44/R53)
Gain A2 = 1 + (R43/R54)
18. GAIN FACTOR