12V vs. 24V hardware
Arclight
Our current rev of hardware is a panel that supports 2 readers, 4
alarm zones and has 4 relay outputs. I'm using a simple UPS circuit
with 3 diodes. How many people are using 24V door hardware vs. 12V?
While 24V mean lower amperage to the doors, 12V is cretainly easier/
cheaper to build UPSs and find nice power supplies for.
Also, I've been doing quite a bit of research on circuit protection.
The 2.0 hardware will have MOV (high amperage) and Zener diode (fast
clamping) protection. All of our inputs are opto-isolated using a
common NEC opto. Is anyone else doing this sort of thing in their
designs?
Code/Eagle files:
http://code.google.com/p/open-access-control/
Pics of the 1.0 board:
http://blog.shop.23b.org/2010/11/open-access-control-v100.html
Arclight
Flemming Frandsen
> How many people are using 24V door hardware vs. 12V?
I've only ever seen 12V hardware.
> While 24V mean lower amperage to the doors, 12V is cretainly easier/
> cheaper to build UPSs and find nice power supplies for.
What I've done is to have unregulated 15-30V DC as the main supply
voltage and then have local DC/DC converters that supply each door
controller with 12V and 3.3V DC, that way the 12V wires are all short.
> Also, I've been doing quite a bit of research on circuit protection.
> The 2.0 hardware will have MOV (high amperage) and Zener diode (fast
> clamping) protection. All of our inputs are opto-isolated using a
> common NEC opto. Is anyone else doing this sort of thing in their
> designs?
Well, I've just stuck 1k resistors on the GPIO pins to keep the
current in the AVRs built-in port protection diodes down in case of
over voltage, but all I interface with on those ports is 5 V, so it's
not the most aggressive environment.
--
Flemming Frandsen - YAPH - http://dren.dk/
Ron Bean
>
>I've only ever seen 12V hardware.
The Von Duprin 5100 doorstrike can be wired for 12V or 24V.
(We're using it at 12V.)
There's a lot of 24V hardware available, but I don't know how many
suppliers stock it.