Is 100% really 100% on?

[nathank]

I'm new to the whole Renard concept, and I don't THINK that this has been raised before - but please be gentle if it has :)

I have built a Renard-C board and am using it for DC operation (although I think that may be irrelevant for this).

Setting the intensity to 100% and then putting an oscilliscope on the output of the 595 chip I'm finding that there is a slight dip in the output at what appears to be a fixed period of time (I'm also very new to oscilliscopes, I have just borrowed one).

What I'm finding is that when I have a channel full on I can see a very slight flicker in the light string.

This slight dip in the output of the 595, is that meant to be there? And if not, can it be removed to provide a constant "on" when the intensity is 100%?

Hope that all makes sense!

Thanks in advance.

[P. Short]

Which version of the firmware are you using? And have you 'programmed' it for DC operation or not?

--

Phil

[nathank]

I used the firmware mentioned here: http://www.doityourselfchristmas.com/forums/showthread.php?t=1612

Are there different types of firmware for the Ren-C? I had a feeling there was only the one type?

Thanks again.

[P. Short]

Oops, I was thinking of regular Renard (which has different code). That firmware doesn't have any option for DC operation, so what you see is normal for the Ren-C.

--

Phil

[nathank]

Thanks for the quick response.

Are there any plans to release a firmware for DC operation on a Renard-C?

[P. Short]

No, I don't have any plans now for modifying that code. It's pushing the limits of the PIC16F627, and isn't easy to work with.

If you are truly using DC hardware (i.e. a DC supply for the LEDs, no TRIAC-based SSRs involved), you might be able to get better results by decreasing the constant in line 172 down to a small number, like maybe 2 or 4.

--

Phil

Edit - from your sig I assume that you are in New Zealand. All of my testing has been done in 60 Hz locales, and it's possible that there are some bugs that may only manifest in 50 Hz locales. How long is the 'OFF' interval when the level is set to 100%?

[nathank]

Thanks for the tip, I'll give it a try.

I'm not using triac based SSRs, instead I'm driving grunty transistors for DC operation.

I'll post the results once I've given it a try. Thanks again.

[nathank]

Edit - from your sig I assume that you are in New Zealand. All of my testing has been done in 60 Hz locales, and it's possible that there are some bugs that may only manifest in 50 Hz locales. How long is the 'OFF' interval when the level is set to 100%?

To be honest with you Phil I'm not sure exactly how to read that on the oscilliscope (all the values and stuff are very confusing to me at the moment!) but I'll do my best to find out for you...

[nathank]

Hmm, I changed that value and re-flashed the PIC but it didn't appear to make any difference.

Can I ask what that value actually does?

[P. Short]

It forces the output off for a number of slot-times near the end of the AC cycle, with the intention of preventing 'flashing' with LEDs or other low-current lights (with SSRs).

--

Phil

[nathank]

Ah I see...

Please excuse my ignorance, but is it possible to set this to a value of zero? I only tried a value of 2 last night.

Thanks.

[P. Short]

You can try it, the worst that can happen is that it doesn't work at all. However, I don't think that it will make any difference. The standard board (without any rework) is always going to have those 'OFF' periods, as the zero-crossing signal forces the signal off (in hardware) for as long as the zero-crossing is active.

--

Phil