I'm trying to wire up a buzzer to my garage door so it will sound when the door opens. The courtesy light puts out 32V and the buzzer will draw about 10mA.
What could I use to step down the voltage to the 15-16V the buzzer requires?
Cruschow's condition, "if the 32V is DC," may have slipped past you. Are you certain it is DC? Do you know what DC means? What is the source of the 32VDC?
Cruschow's condition, "if the 32V is DC," may have slipped past you. Are you certain it is DC? Do you know what DC means? What is the source of the 32VDC?
Oops, I just forgot to respond. Yes it's DC, the garage door opener has a 24V DC motor and the LED courtesy light module (which I'm hooking into to run a buzzer) run on what appears to be 24-32V DC.
Both the 0.1uF input capacitor and 1uF output capacitor are to insure that the LM317 remains stable (doesn't oscillate). They should be mounted close the the regulator pins.
Why not just put a 160 ohm resistor in line with the buzzer (works for AC or DC)... 160 ohm * 10mA = 16V dropped across resistor, 16V across buzzer.
I*I*R (power) would be 16 milliwatts through the resistor.
Both the 0.1uF input capacitor and 1uF output capacitor are to insure that the LM317 remains stable (doesn't oscillate). They should be mounted close the the regulator pins.
Why not just put a 160 ohm resistor in line with the buzzer (works for AC or DC)... 160 ohm * 10mA = 16V dropped across resistor, 16V across buzzer.
I*I*R (power) would be 16 milliwatts through the resistor.
I'll probably get shouted at for saying this, if its a mechanical buzzer that uses about 100ma then why not just wire a 1.2w 12v bulb in series with it, the kind used for backlighting dash's.
If its a low current beeper though it'll probably fry it as the lamp will pass too many ma, you might be able to use a 20v 1.3w zener to lose the volts for a low current beeper, connect the cathode of the zener to the + supply (backwards).