HEATER CONTROL 3000 WATT

[Ernie62]

I have been an Elect. Eng for over 40 years and every day I learn how little I know another 20 years and I will be quite stupid.
Well anyway I have been using controlers for a lot of years and this is what I desighed and made many times It can also take 220vac

120vac heater controler

120vac 3000w heater control.png (15.18 KiB) Viewed 1226 times

All parts are easy to get If you have any questions I will be glad to help

[HDNB]

so not being an engineer, i'm curious.

what is the cap and resistor for on each side if the pot?

Is that a symbol for a rectifier bridge infront of the triac? purpose? ...i thought it took 4 diodes to make the ac to dc conversion to control a triac.

why would you supply one leg 120vac unfused to the boiler element?

would it not make sense to just put a breaker, or a gfi breaker in front of the whole works and do away with the fuse on the one 120 leg?

"outputpower" is an ammeter?

i need an explanation with all the fancy symbols to help it make sense...could you describe the circuit for the layman to better understand?

Thanks! i need more knowledge here!

[Ernie62]

All are great questions
The cap and resistor set up the charge discharge for the timing to turn on and off the triac
the two diodes are some as buying a diac which are hare to find and this is easy In real live this is a protect circuit
you are plugging this into your house current which already has a gfi and you do not want to put one in line with another as for fusing only one leg of 110 You always fuse only the hot side the other side is neutral your house is wired the same way
ok coming from the left to right at top of the circuit the top line is your heater a cord and a 110vac plug
line to starting at ac120 comp to the first line going down this is a lamp saying the plug is plugged into the wall and the switch is on
next is a normal wall socket with a lamp wired with It to tell when it is working You could put a amp meter there but it adds to the cost and the lamb comes on dim and gets brighter as you turn the variable resistor (pot) clockwise you are going to monitor your still same as you were using gas so who cares how many amps it is pulling
next leg down is a 3.3k resistor the a pot(variable resistor 25K) down to the right are two diodes or a (daic) then the .01 cap the last led is the triac which is a switch controlled by the pot, cap, and diodes
Now bottom left starting at 120vac you have a switch to turn it off and on a fuse to protect you and the equipment. I have my equipment it the bard and want a local fuse if it blew the house circuit breaker that is over 600 feet away and it would probably be raining (my luck)
I hope this explains some to you Remember there are a lot of ways to skin a cat. This is my way and before I built it for a still I used the to control motors and equipment at my work and has worked for me for years hope it works for you If it is not what your looking for please keep looking and I wish you well and gooood stilling

[shadylane]

Good circuit description Ernie
But it's now cheaper and easier to buy a ready made phase angle controller than it is to build one.
Some were in my junk box is a home brew controller for a soldering iron.
The circuit was basically the same but the component values were a little different.
The dam thing worked good but generated so much RFI that I couldn't listen to the ham radio and solder at the same time.

edited
RFI = radio frequency interference.

[Ernie62]

I understand I am a hammer also.

[BigSwede]

Very nice write up and contribution Ernie, thank you. I am sure this will help a lot of people. This can be put together much cheaper than an integrated phase angle controller, which is unobtanium short of outrageous shipping charges in many parts of the world.

[rad14701]

I use a bridge rectifier to make zero hysteresis controllers... This is a cheap and effective alternative even though there will be some hysteresis like some of the cheaper router controllers where you have to tun them up 1/3 - 1/2 way to get them to start working...

[HDNB]

so since we got some engineers here... my new controller (240vac on a 5500w element) uses a 5k ohm pot on a 80a ssr. the pot is not linear. it comes on at 6A at about 50% and ramps up very quickly to 21.1A at full smoke. i can turn it down to 3.3 A once it is engaged.
is there a way to get more linear control from the pot?

[bellybuster]

A linear taper pot will give mostly even resistance compared to the rotation whereas a log taper (audio taper) pot is not linear.

[HDNB]

A linear taper pot will give mostly even resistance compared to the rotation whereas a log taper (audio taper) pot is not linear.

aha. where were you when i bought a pot for an e. guitar? any suggestions for a source for a "linear taper pot"?

[rad14701]

so since we got some engineers here... my new controller (240vac on a 5500w element) uses a 5k ohm pot on a 80a ssr. the pot is not linear. it comes on at 6A at about 50% and ramps up very quickly to 21.1A at full smoke. i can turn it down to 3.3 A once it is engaged.
is there a way to get more linear control from the pot?

What you are describing is hysteresis caused by simpler analog circuits... You have to turn those controllers up 1/3 - 1/2 way, usually to about 33VAC flowing in an 120VAC circuit, before the controller comes to life... From there you can adjust up or down, usually down to between 3 - 5 VAC... Single time constant circuits are the worst at this... Double time constant circuits are better... And hysteresis free circuits virtually eliminate the issue... Digitally controlled circuits are usually made to eliminate the issue as well...

[bellybuster]

A linear taper pot will give mostly even resistance compared to the rotation whereas a log taper (audio taper) pot is not linear.

aha. where were you when i bought a pot for an e. guitar? any suggestions for a source for a "linear taper pot"?

I'm not smart enough to say if a pot change will help, Rad prolly can but any guitar supply place with have both pots. I build electric guitars in the winter, that's where I learned about the different pots. I can tell you that the linear taper pot works much better with the simple SSR controller.

[rad14701]

Audio taper is logarithmic with the % rating measured at mid-point... The % rating determining whether ramping is front or end loaded... Linear taper remains linear from 0 - 100%... Power controllers perform more predictably with a linear taper potentiometer...

[cornz]

http://www.ebay.co.uk/itm/High-Power-40 ... 43bf06ab43" onclick="window.open(this.href);return false;" rel="nofollow

These work a peach with my 2k2 220v kettle element....
gentle simmer to rolling boil....