Simple project

[PaulMcGuinness]

Hi all,

I need someone to design a circuit and make a prototype for me.

THIS IS A PAID PROJECT - So please quote a cost or PM me.


I need a device that stops a letter-box flap from being opened until a signal (3-5vdc) is send for >100ms, at which point the flap is released for 10 secs. There should also be the option to hold it open indefinitely, and not to lock again until the flap returns to its normal position.

I have in mind the following:-

It should run on anything from 5 - 12vdc.
2 x Solenoid bars to hold the flap closed
Hall-effect or reed-switch to detect open position
Positive voltage on Pin 1 >100ms opens solenoids for 20secs.
Positive voltage on Pin 2 keeps solenoids open until voltage drops.
If pin 1 used, then the solenoids will not lock until 10 secs after flap closes.

[Drake]

Are you trying to prevent entry or just keep a draft out?