StillSmart

Mr Four Square wrote:I had the same experience Ant. Using a similar digital watt meter through a controller. It did a couple of runs dialled back to round 1000 watts and then the dreaded smoke and sparks,

I tried EDs suggestion of running it through a plug in power monitor to measure watts and no problems since. (I think those devices only work on loads under 2200 watts ? )

Has anyone found a digital meter that can handle higher loads through a phase angle controller?

My plug in power monitor I have seen measure to just below 3000 watts,it may go a little higher in a slightly less 'hicks from the sticks' location.I believe it is rated at 3KW.
I live in one of the the Scottish fag-ends of civilisation.
Here,telephone broadband finishes four miles from the local exchange,because it it has been gobbled up by then,and as I am six miles away,no chance.
Two chances to get online here,slow sim card wifi; and not much faster but more expensive satellite.
But on the rare occasions that the sun shines,this is Gods country,and I wouldn't trade it for faster Internet.

Robert.

This one is rated for 100A rather than the usual 10A.

Good call on nature over broadband. If 4G ever reaches you you'll be sorted. I only have 3G internet myself. I don't bother with a landline at all. It's still as fast as classic broadband and a lot better than dial up modems were.

I have been struggling to get faster bb for 12 months. No go so far.

My brief experience with a working controller leads me to a thought and a question.

The question is: what is the lowest wattage each of you experienced guys use and on what size rig?

Tbe thought is that adjusting the size of the pot could eliminate the dead area at the beginning and give finer control of what remains. I thought about a ten turn but that might be overkill. How fine do you reallly need to go?

ant,your electronics knowledge usually fries my brain trying to keep up,but if it helps-
I usually strip 25 litres of 10-12% @ around 1700w.
And spirit run a similar volume at around 30% @ 1500w.
In my pot still.
After using a full 3Kw to get the boiler up to speed,and the coils wanting to run.

Robert.

Thanks. Anyone else? Watts used, element size, boiler size, type of rig?
Or do I have to build my boiler next? Then size to that.

Hi Ant I run a T500 boiler round about 1800 watts on full.

I keep an eye on the amount of distillate flow I'm looking for and modify the wattage to suit.

Strip and spirit runs I let the boiler heat up on full then wind it back to a 1000 watts when the distillate starts to drip.

On the strip run I'm looking for largest flow I can get out of the Liebig without any steam and keep winding it up from 1000 till it finishes on full noise.

On the spirits run, once the distillate starts to drip I wind it back to round 300 watts and collect the fores. This time I look for the thinnest stream I can get and move slowly up from there maintaining that thin flow. Next step is usually 500 then 750 then I finish the spirit run round 1000. Once I'm into the tails I start looking for maximum flow without steam and start winding it up as per a spirits run.

Thank you.

Anyone with a keg and two inch column?

Anyone ever tried a log pot instead of a linear?
I can't help thinking it would tend to even out the non linearity if wired the right way around.
Not a perfect match but better than linear. Maybe.

ant wrote:Anyone ever tried a log pot instead of a linear?
I can't help thinking it would tend to even out the non linearity if wired the right way around.
Not a perfect match but better than linear. Maybe.

Got my interest please expand and explain your thoughts on this.

AidanMac

Well. The controller is non linear as we know. It takes a big turn at the beginning to have a little effect and less and less turn to have a similar effect until it all bunches up at the end. That is with a linear pot.

A log pot has a bigger effect at one end and tapers down having progressively less and less effect for a similar amount of turn as you head to the other end. It is used to compensate for non linear situations.

It won't be an exact match to make things comepletely linear, the pot is log and the curve is sine, but it should improve things. Maybe.

You would have to try it both ways around to see which way is which. By which I mean the centre pin and one of the two other pins. One way will hopefully even things out and the other make it even worse. You may end up with the knob working the opposite way around to usual.

Got the replacement meter.

Now comes with instruction leaflet and back cover.

The 400v capacitor has been replaced by one that is less than 300v. A downgrade.

Fitted it but not run it up yet. Busy day.

Came across an interesting alternative. It measures true RMS for about $15 including postage. Astounding.

Of course the one I have might. I have no way to test that. It's down to the sample frequency.

The following link is ludicrously long but should work if you click it.

http://m.aliexpress.com/item/32253510358.html?productSubject=D69-Multi-functional-LED-display-panel-meter-voltmeter-ammeter-with-active-and-reactive-power-and-power&productSubject=D69-Multi-functional-LED-display-panel-meter-voltmeter-ammeter-with-active-and-reactive-power-and-power&productId=32253510358&productId=32253510358&productId=32253510358&product=%7B%22adminSeq%22%3A122378658%2C%22aeProductSKUEsiDTOs%22%3A%5B%7B%22skuBulkDiscount%22%3A10%2C%22skuBulkOrder%22%3A10%2C%22skuBulkPrice%22%3A11.61%2C%22skuPrice%22%3A12.90%7D%5D%2C%22isSkuProperty%22%3Afalse%2C%22lot%22%3Afalse%2C%22multiUnitName%22%3A%22pieces%22%2C%22numberPerLot%22%3A1%2C%22oddUnitName%22%3A%22piece%22%2C%22offlineDate%22%3A1435275034000%2C%22productId%22%3A32253510358%2C%22productMaxPrice%22%3A12.90%2C%22productMinPrice%22%3A12.90%2C%22seotitle%22%3A%22D69+Multi-functional+LED+display++panel+meter+voltmeter+ammeter+with+active+and+reactive+power+and+power+factor+80-300V+0-100A%22%2C%22shopNumber%22%3A613696%7D&category=%7B%22categoryName%22%3A%22Voltage+Meters%22%2C%22categoryUrl%22%3A%22http%3A%2F%2Fwww.aliexpress.com%2Fcategory%2F15370310%2Fvoltage-meters.html%22%7D&tracelog=wwwdetail2mobilesitedetail

To answer the log pot query a bit more explicitly.

Pot has three terminals. A lead to the wiper and one to either end. You have to use the wiper unless you want a fixed resister. You can then choose one of the other two terminals for the other connection. As it is a log pot it does have a sorta polarity. One end has a greater effect than the other per degree of turn angle. Wire it one way and the non linearity of the pot will compound the non linearity of the PAC. Nightmare. Wire it the other way and the two non linearities will tend to cancel each other out and produce a more linear response. Maybe not a very good one. That's why I'm asking who tried it? It's why log pots were invented after all. This might ideally need a reverse or anti log pot to have the knob turn the way you expect. They make those.

It is possible to convert a linear pot into an approximation of a reverse log pot with a fixed resistor 20% of the value of the pot. You can create custom curves with different value resistors. I will try and report back.

Hi Ant

I think if you add extra resistance to one end of a linear pot, then use that end along with the wiper for your two connections, all you'll find is you've lost some of the adjustment range, you'll never be able to fully turn it to zero resistance.

You would need to get old fashioned plot your output from your power controller (controlled by a linear pot) on a graph, for example degrees turned on the knob vs measured power, that should give you some sort of curve, maybe you could find a pot with an opposing curve to smooth out the control and make it more linear.

Another option, depending on how fine control you want, if you spent some time measuring the resistance needed for each power setting, could be to get a multiple way rotary switch and solder individual resistors of different values for preset powers, you would loose the fine control of a pot but you could create linear steps, if you know what I mean.

Yes I do know what you mean and you could do that but a rotary switch is more expensive than a pot. I'm not quite as cost efficient as Brian but I try to keep cost down.

Speaking of Brian his print out of his control dial is probably a good fit to most if not all of these device response curves.

But I think a reverse log pot might be a fair approximation and it can be tweaked.

You are right of course. A fixed resistor in series would stop you reaching zero resistance. This would stop you reaching full power. You could use a simple single pole switch as as a shunt to short circuit the input and jump to full power. That is not the specific plan though. This is just an experiment to decide which pot to buy next. An actual log pot would not have the problem.

I'll have to go back to my source to describe how the approximation works. Please bear with me.

You can also put a fixed resistor in parallel with the pot track to reduce the max value and skew the curve. In this case you don't need a separate switch. The pot will jump to zero resistance as the wiper meets the terminal.

I'll get back to you shortly.