Controlling higher voltages with digital

Discussion in 'General Electronics Chat' started by pitzy, Jul 27, 2004.

  1. pitzy

    Thread Starter New Member

    Jul 27, 2004
    I'm a microcontroller programmer, and I work with 5V CMOS logic.
    I want to transmit fast higher voltage signals (24V), but NPN-common-emitter will only allow me to switch the ground.
    Can I use another transistor combination so the MCU switches the higher voltage to a load? (the ground is common). Also, the MCU mustn't experience a voltage higher than 5V.

  2. mozikluv

    AAC Fanatic!

    Jan 22, 2004

    would you consider using an SCR to deliver the 24v and letting your MCU apply the gate trigger current/voltage of the SCR? the gate trigger voltage is only 1.5v and 30ma. can you MCU deliver this current value?
  3. beenthere

    Retired Moderator

    Apr 20, 2004

    If your 24 volts is AC, consider the SCR. They are as small as a TO-92 package, if your current is low. But if it's 24 VDC, they won't work. They will latch on and stay that way until the voltage across the device/s goes to zero.

    For DC, think about TO-92 hexfets, like the VN10LP. It withstands 60 volts, carries 200 mills, and goes full on with 5 volts applied. Switching time in tens of nanoseconds, too.