In order for me to keep it very simple it would take ADC from lipo cells which are 3.7v. I might use a resistor 4.7k on the connector it self or without a resistor since it shouldn't have any spikes in voltage. To take frequency I was thinking just to use 2 resistors 1k and 100ohm to drop the voltage. To power up the pic I was thinking to use TO-92 0.5% LDO and 1 or 2 small capacitors. I'm not going to use voltage reference to keep it simple and ADC probably should work within 1%-3% accurate. As you can see 1 PDIP microchip, 1 LDO, 1-2 capacitors and just connector glued and soldered directly to microchip. Using software rs232 I don’t need Max232 so I can just use serial female connector with 2 resistors and connect it directly to microchip whenever I need to upload the data. Sure I can make PCB at home but I just want to keep it very simple so my friends can use it as well just to pay for parts or so. I bought PicBasic just for fun since I like electronics and I don't intend to make profit but maybe I might sell it for a small fee. I have regular job which pays my bills and I don't mind to spend money for my hobby that I like.