Normally for signals eg.
- soundcard => NPN inverter => HALL-input
- VR to HALL adapter => NPN inverter => dash input (or other input) with strong pullup
- Logiclevel ("i259") ignoutput or output from PC (eg. for CNC milling applications or other experiments: Parallel port, or raspberry / beaglebone output) => NPN inverter => 5..30V relay or small pneumatic valve DC-solenoid, in either case with flyback protection (1..3A diode eg. BY399, stripe-marked cathode to solenoid+, anode to solenoid switched- = output of NPN inverter. This flyback diode is often hidden in the relay/solenoid connector/socket).
- protecting processor signal from external environment (static discharge or other damage; eg. devices ordered with bridge output driver eg. for electronic throttle are internally equipped with NPN-inverter protection for the PWM signal)
- many other useful applications
If you need slightly more than 210 mA (eg for 12V flyback-protected relay or other solenoid with resistance<71 Ohm) or greater than 37V, specify in the order comment.
DSUB9 and/or shrinktube provided.