Troubleshooting a triac based controller

[3rdson]

I have finished my second boiler using a 30L keg with a 120v 1500 watt element. I have not done a test run yet so I'm not really sure if this is too much heat or not but am assuming that it would be preferable to have the ability to reduce it a bit. I was planning on building the triac controller based on Pinto's design.

I tried both versions but only the first one works with my dimmer. The controller does work ... however, at full on it will only reach about 1390 watts, (1410 wired direct), which I understand is pretty normal but when I turn it down it will only come down to slightly under 1200 watts and then it turns off completely. This could actually be enough for me but I should be able to turn it down quite a bit lower than this, shouldn't I?
Assuming I have it wired correctly and I am fairly sure I do, is there any way to test the triac or do I just blame it on the dimmer and try a new one? This is probably the simplest and easiest.
One other point is the triac is not the Q6040J7 ... the store cross referenced it to a NTE56031. I looked at the specs for both and they seem to be identical so can't see that as the problem. Also, I am using an adjustable 100 ohm resister 25 watt set to 75 ohm.
Any suggestions on my next course of action would be much appreciated.
Thanks
3rdson

[MuleKicker]

I have never fooled with this design, but If I remember right, changing the resistor size will affect the range. I dont belive your problem is in the triac itself. Something with more/less resistance changes the rate at which the capicitor is charged/discharged, firing the triac. Here is the link to the heat control thread where this is discussed over and over. It is quite a read, but invaluable to someone building that controller. There is also a triac thread in the lounge, but that one has been cleaned up quite a bit.

[John Barleycorn]

however, at full on it will only reach about 1390 watts,

You're right at about 93% power ... which seems pretty fair. I bought one of those commercial router speed controllers and it doesn't appear to get me quite as high.

but when I turn it down it will only come down to slightly under 1200 watts and then it turns off completely.

Sounds like the triggering ... might need some delay? Also, pots are typically not very linear.

How are you measuring your power?

--JB

[3rdson]

@MuleKicker
Yes, I do remember seeing reference to different resisters in one of those 2 threads but the 75ohm 25 watt was the original design and it appeared that most were using that one. I wasn't sure how far I could experiment with the values as I didn't want to have to replace my triac ($22 here in Canada). I seem to recall that Centar (maybe), mentioned a 1k ohm 1/4 watt so will look for that message again as well.

@John Barleycorn
It has to be the triggering like MuleKicker suggested as well. Off to the parts store for a few resisters.
I was measuring the power with a cheap killaWatt meter. Being an el cheapo unit probably means the readings are off a bit but for my purposes it should be close enough.

While I am out I will pick up a new dimmer as well as the resisters.

[rad14701]

I have built this controller several times and the second implementation with the circuit connected to MT1 should be scrubbed as it rarely works without having specific components... The control circuit should be driven off the MT2 (output) terminal of the Triac... My current 120V Dimmer + Triac controller uses a 1200 Ohm (1.2K) 1/2W resistor... The operation range is that it initially fires into action at ~30V, puts out a maximum of ~117V and can be backed down to ~5V when powering a 1500W element...

[3rdson]

Hi all ... sometimes I forget to follow my own advice ... and that is you get what you pay for.
It appears that my original wiring was okay and the source of all my frustrations for the past couple of days were related to the cheap KillaWatt meter I was using to judge if it was working properly. It would appear that the KillaWatt meter does not like you messing around with the sine wave (I'm guessing at this).
After I finally clued in and got out my multimeter to check it, all seems to be fine.
The KillaWatt meter was just so convenient with all the readings I wanted at the push of a button. Sometimes things are too good to be true!
Thanks for your help and suggestions.
3rdson

[MuleKicker]

Here, try these. They work good Here

[3rdson]

Here, try these. They work good Here

I do plan on building a 240v version and one of these meters would be a nice addition. I may ad one to this one as well.
I am currently doing a run and had it down to 60v and the temp seemed to be steady ... even rising, so I increased it to 80 volts and it seemed to stabilize and even drop a bit. I only waited 30 minutes to stabilize so that probably wasn't long enough.
What voltage would be a "normal" setting for a 30L keg (20L wash), with a 1500 watt element?