View Full Version : ZC Power and 5VDC

05-27-2009, 03:46 AM
Just a question on what voltage is required to make ZC.Have seen some use mains power, i have a 12.6VAC transformer.Is there any minimum or maximum voltage required.Im talking for the Renard and maybe i should post it there but there are 2 parts. Can i use 12.6 AC for ZC, then convert and reduce it to ~5VDC to power the actual controller?Would i be better looking for a lower voltage or maybe even put the whole idea in the way to hard basket ( which i tend to look in now and then and say...it isnt impossible, just hard)
Cheers Synnie

05-27-2009, 04:03 AM
check my schematic is the 'another controller" thread. i have used that same power curcuit with down to 6v AC unput. the h11aa1 opto doesnt seem to mind althought there is some talk about the turnon voltage in practice i havnt seen it to be an issue. the only thing i can say is if you want to use a 78l05 regulator or similar you need to try and keep the input voltage below about 12-15vAC or else the heat required to be disipated by the regulator seems to get out of control.

there are some better regulators out there and if you wanted you could look at a switching regulator and get alot better efficency. i have found that with a switching regulator the 24v AC transformers we get with the lights can power both the ZC and a 3 AMP 5v supply. drawing under 800ma rfom the transformer. works quite well. I guess it would depend on the load of the board which way i would recommend.


05-27-2009, 04:03 AM
that is the way the REN64XC works. The ZC signal "voltage" would be based upon the threshold voltage of the chip. Normally this is in the range of 2 - 3 Volts (see chip specs)

haha! Peter beat me to the punch! :D

05-27-2009, 04:30 AM
Thanks Scorpia, i kinda have an idea now...i did say kinda...lol.I have a few plug packs ranging from 6V to 36V but need to check how many amps they have. Looking at a switching regulater but it sounds too confusing just at the moment.Can understand the 7805 part, ill look in my box of packs for a 12V transformer and i should be right...hopefully.They dont have a centre tap on the plug packs though...would that be a problem for the ZC?

05-27-2009, 05:48 AM
dont forget 12v AC. most plugpacks are DC

05-27-2009, 06:23 AM
The ones with the lights are usually AC, i have a few low voltage ones also from various infotel cr*p that finds it way into the house.

05-27-2009, 06:38 PM
There are several solutions for building a ZC detector, and each is going to have its own input requirements.

The H11AA1 solution can tolerate a full 125VAC on the input but most be current-limited with some resistors. The other side of the H11AA1 works at logic levels, and the only thing connecting the two sides is a beam of light.

A PIC chip can even tolerate a full 125V on the input pins if you sufficiently limit the input current. I've seen that done in some designs (and in fact it's documented by Microchip in Application Note AN521) though I probably wouldn't try it myself. It is a cheap solution, however... the only part is a resistor.

05-28-2009, 03:15 AM
We have 240VAC mains and i aint going to go anywhere near that with resistors or a H11AA1 so will use a low voltage transformer. I can isolate 240 easy enough as have bought quite a few 3 pins sockets ala computer power cable style and go low voltage.not as scary...lol

06-05-2009, 09:50 PM
Scorpia, i have a standard 12v wallpack which isnt a centre tap transformer so im going to say it would be ok to use with your design for another controller in the region of ZC and also 5v power for the board?
Ta Synnie