Dimmer

[Atom058]

Steve - Thanks for your reply - The transformer is from Jameco (www.jameco.com), P/N: 249412. The spec sheet says that I should be getting 8VAC @ 1.6A (I know that is a little over-kill on the amperage, but it is what I had lying around), but I am measuring 9.8VAC across the input to my bridge rectifier. Using a voltage divider (4k7 & 10K), that gets the DC voltage to GPIO.4 down to 4.33VDC. The cap is a 470 uF 25V electrolytic.

Let me know if you need anything else... Thanks!

Atom058

[Atom058]

Steve - Any luck with the info that I posted?

I've been looking at some related posts and I am wondering if the timing problem is related to the maxdelay value. If I am running at 60 hz, that means that I complete 1 cycle every 16.7 mS. Or, I cross zero every 8.35 mS (8350 uS). Is that correct? In the code, MaxDelay is 6000 uS. Is this where my problem is?

Can you tell me why the transformer and 470 uF cap is of interest to you? How does this affect my timing?

Every day is a learning experience and I'm always looking for more!

Thanks! Atom058

[Atom058]

I would love to hear from anyone that has successfully built this dimmer that is discussed on this thread. I have followed the code and schematics (as well as the changes to both) and can not achieve the end result. The circuit and code, as it stands now, will allow me to go to full on and full off by quickly tapping the inc/dec buttons. This part works perfectly. If I press and hold the inc/dec buttons, the lighting level changes gradually, just like it is supposed to, but I get flickering. Mister-e seems to think that it is a timing issue - and I am in agreement, but I do not know where to make adjustments. If anyone can give me some trouble-shooting ideas, I would greatly appreciate it.

I think this is a great design that has many uses. I would love to get it to work and post my final results!

This circuit, once I get it right, is going to be the basis for a larger design, But until I get this part working, I can not move forward.

Please help!
Atom058

[mister_e]

Yes it's a timing problem, and there's no way to determine the exact one between all transformer brand and model. Adding a calibration process is possible but... usefull?

grabbing the signal directly from the li ne is the only way i see to make it work with all transformer.

Transformerless PSU is another way.... i hate that but if everything is properly done and insulated, the user shouldn't be hurt one day.

Give me a couple of days.. i'm on a rush now.

[Atom058]

Steve - Thanks for your reply - I was actually on the path of a transformerless supply like you suggested. I have built the design that was presented by Melanie in another thread and get a nice clean 5VDC to drive my pic. I am pulling the AC for the trigger and putting it through a 20M dropping resistor (to go to pin 3 of my pic) per the schematic for the PIC REF-4 application note. However, this only drops the voltage to around 30V AC. Do I need to get it down to <= 5VAC or is 30VAC OK?

Atom058

[mister_e]

I did something like that for one user here that use a 10Meg directly from the main to a PIC input. The PIC internal diode do their job. As now it seems to works. The user is still alive... Just make sure you properly insulate your stuff.....

The 30VAC you get is without load...just your voltmeter.

[Atom058]

Thanks Steve! I will give it a try and let you know what happens!