high voltage comperator / main line monitor 1

[savepower]

Hi @all,

I'm looking for a bright idea to monitor the main line for zero voltage crossing, with the lowest possible power consumption. Does anyone have a hint with a current consumption <5µA (my application 230VAC 50HZ)?

Regards,
Andreas

 

[MacGyverS2000]

You'll need something passive for that low power spec... active components won't touch it.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[VEBill]

Why the extraordinarily low current requirement when there is a commercial power source right there?

 

[savepower]

Hi,
@macgyver:
Maybe a MOSFET with a very high Vgs would work, but I haven't seen such a device yet

@VF1BLL:
I don't want to waste energy, that's all.

Regards,
Andreas

 

[Skogsgurra]

Then find a solution that works and apply it. Starting out with a current draw specification without saying at what voltage doesn't say much about energy savings.

The 5 uA at 230 V - if that is what you meant - equals a little more than 1 milliwatt. I don't know if energy savings should start there. There are tens or hundreds of other savings you can do.

Anyhow, a capacitive coupling between 230 and your device will not draw any energy at all. Or very little. Then you can use your saved milliwatt to supply 3.3 V to a micro running at about 100 kHz where it doesn't draw more than perhaps 20 or 30 uA, which equals less than 100 uW.

Use the micro to adjust for the 90 degree phase shift in the capacitor.

You may need to put a low pass filter before the input pin to avoid HF hitting the pin directly. But that won't consume much power.

One question: Were you joking when you said that you wanted to save energy?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[savepower]

Hello Gunnar,

my application is a Staircase lighting time switches (hopefully) designed for low power. Right now the whole circuit consumes less then 50mW at 230VAC/50Hz. "Less then" should mean: I do not trust my meters which say 21mW (I'm waiting for a special standby power meter). The PIC micro is always running with 4MHz, maybe I can find a way to let the PIC goes to sleep mode. I'm not sure about that, because the PIC is filtering some annoying glitches and spikes from the main line to determine if someone pressed a switch or not.

So, to sense the main line consume ~5mW. Hugh, this is 25% of the overall power. Maybe, I'm not so wrong to start thinking about a better/other sense circuit.

I'm open for other ideas, therefore I will check the capacitor divider. Keep you informed.

Regards,
Andreas

 

[Skogsgurra]

We have designed a terminal for telephone applications that senses 230 V using a pick-up wire along with the houshold wiring. No connection at all. The device needs som punch to do its work and is therefore battery driven. The current consumption is around 12 uA (from the battery when idling) and the time between battery changes is between three and five years.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[John2025]

Am I missing something?
21mW = .021W = .000021KW
.000021KW x 24hrs per day x 365 days per year = .18KwH per year
.18KwH x .15$US per KwH = $0.03 per year.
You think it's worth improving on this?

 

[savepower]

Hi John2025,
you are absolutely right. Improving from 0,7W down to <0,05W was a huge step. Now I'm looking to gain some more without increasing the BOM costs to much.

Regards,
Andreas

 

[MacGyverS2000]

I think you're chasing unicorns for the sake of a trophy no one will care about. Simply "do your best" and be done with it.

Dan - Owner

http://www.Hi-TecDesigns.com