Propeller controlled doorbell
dr hydra
Posts: 212
in Propeller 1
I'm looking to use a propeller to control a doorbell through an uln2003. I'm going to running the doorbell solenoid at 12v...will the uln2003 provide enough protection between the the solenoid and the propeller chip?
Comments
Do keep in mind that the ULN2x03 has about a 1.4v drop from ground to collector; this may affect your output.
Try to find the model with highest solenoid resistant
the 3V3 supply has enough decoupling that kick-back doesn't raise its voltage excessively.
A dual MOSFET + diodes + bistable relay can work quite well, I've used this in a circuit running from
1.5mA total at 12V+, you need enough capacitance to hold up the rail during the bistable relay
pulses, and run microcontroller slow.
They use 16volt (10w) transformer, so it's pretty low voltage.
Are you using 16VAC?
If DC, you could use a mosfet.
A 50cents MCU could power a nmosfet-solenoid-driver on the low-side, like this one:
http://www.mouser.com/ProductDetail/ON-Semiconductor/NUD3124LT1G/?qs=sGAEpiMZZMshyDBzk1/WizSW%2bwlCH/hM25spW3xjdko=
Internal Zener Eliminates Need for Free−Wheeling Diode.
Else are you referring to an electronic lock.
I think it's the classic electric striker "ding dong" type which some people prefer.