I have a fotodiode siemens sfh 205 f and a fototransistor, that i dont know the type model..., i think is siemens too. So how can I connect these components to arduino?, i post the components in attachments, I need to connect the fotodiode to 5 v and a resistor but i dont know the value, and for the transistor i dont know nothing about it.
First find out the pinout of the components. Phototransistors are fairly simple, you
normally use them in a resistor divider (don't connect the base if it is brought
out to a pin) - they are quite sensitive but slower than diodes can achieve.
A diode can be used in various ways differing in the bias voltage (zero bias,
reverse bias, or just a plain voltage source). Reverse bias is the fastest (low
capacitance) but needs a circuit to convert current to voltage. Zero bias also
needs such a circuit. If you use it as a voltage source it gives a roughly
logarithmic response to light intensity which can be useful. This mode is
not rapid in low light.
Reverse bias has some small leakage current even in full dark, note, zero
bias is better here (but a lot slower).