-1
\$\begingroup\$

This question already has an answer here:

I'd like to use PBSS4350SS transistors for driving multiple low power solenoids, but looking at the datasheet I can't figure out what value the base resistor (R1) should be?

schematic

simulate this circuit – Schematic created using CircuitLab

\$\endgroup\$

marked as duplicate by Community Aug 22 '18 at 8:52

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

4
\$\begingroup\$

Work out the current through L1, roughly 12V divided by its resistance.

Divide this by the minimum transistor gain from the data sheet, this gives you a minimum value for the base current.

The voltage across R1 is 3.3V-transistor VBE or about 2.6V.

Divide this by the base current to give you the maximum value of R1, in practice you need lower this by about 10% to ensure the transistor is driven into saturation.

\$\endgroup\$

Not the answer you're looking for? Browse other questions tagged or ask your own question.