Homebrew_PCBs

Does anyone have one or more of these they are happy to part with for very little. 240V supply required, SSR output preferred.

As postage may be an issue, I live in UK.

Thanks
Dave

I have some Omega CN9121 controllers.

Kerry


David C. Partridge wrote:

Hi David,
There are quite a few PID temperature controllers on Ebay
at good prices as long as you do not mind ordering from China / Hong Kong. Search using "temperature controller PID"
Les.

Kerry,

Unfortunately though they would seem ideal in most all respects, as far as I can tell from the manual they are about 6.25" deep, and I don't have much over 3" to play with behind the panel.

If I've got that wrong, please let me know.

Regards,
David Partridge


-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of Kerry Wentworth
Sent: 12 March 2011 14:56
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] WTB: PID temperature controller

I have some Omega CN9121 controllers.

Kerry

Thanks, I Saw those, but was hoping I might score one cheaper - also suspicious of the anonymous off-brand Chinese parts - maybe unjustifiably ...


Regards,
David Partridge


-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of Les
Sent: 12 March 2011 15:53
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: WTB: PID temperature controller

..eBay ...

The one I have wired up would take about 5" behind a panel, including
the connector. That could be reduced a bit, but 3" it not even close.

Kerry



David C. Partridge wrote:

David, You could try making one. The REPRAP group makes pid temperature
controls for the heated bed and extruder.

Jeremy


[Non-text portions of this message have been removed]

> Thanks, I Saw those, but was hoping I might score one cheaper - also
> suspicious of the anonymous off-brand Chinese parts - maybe unjustifiably

...


I ordered some off eBay to see what they were like. They're pretty cheap
($US25), so I won't be too upset if they're duds. They should show up this
week sometime.

According to the manual they have a depth of 100mm (~4"), the bezel sticks
out 9mm (~3/8") You could probably dismantle them and re-arrange the parts
to fit it in a shallower hole.

They have SSR & relay outputs. There are also timers in the same format.

Tony

Hmmmm .. Prices including delivery to UK and likely customs charges (20% plus about $18), aren't as comfortably low as that.


Regards,
David Partridge


-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of Tony Smith
Sent: 13 March 2011 10:44
To: Homebrew_PCBs@yahoogroups.com
Subject: RE: [Homebrew_PCBs] Re: WTB: PID temperature controller

> Thanks, I Saw those, but was hoping I might score one cheaper - also
> suspicious of the anonymous off-brand Chinese parts - maybe
> unjustifiably

...


I ordered some off eBay to see what they were like. They're pretty cheap ($US25), so I won't be too upset if they're duds. They should show up this week sometime.

According to the manual they have a depth of 100mm (~4"), the bezel sticks out 9mm (~3/8") You could probably dismantle them and re-arrange the parts to fit it in a shallower hole.

They have SSR & relay outputs. There are also timers in the same format.

Tony



------------------------------------

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> Hmmmm .. Prices including delivery to UK and likely customs charges (20%

plus

> David, You could try making one. The REPRAP group makes pid temperature
> controls for the heated bed and extruder.

Ok, I looked up the RepRap PID, and they use the 'usual chip' for the
thermocouple, the AD595. Sparkfun - http://www.sparkfun.com/products/306 -
have them for $18. The other 'usual chip' is the MAX6675, and it's $12.
Ouch. You still need a display, controls, microcontroller, PID coding,
power supply and a few other bits & pieces.

I think I'll take my chances with the $25 eBay unit.

My only problem with that unit is it doesn't (I think) send a signal when it
reaches temperature, you could use that to start a timer. It has an alarm,
but that's only for under/over-temperature. I figure I can do it by
monitoring the heater, and when it switches off for the first time use that
to start the timer.

Oh, and I should mention it doesn't have a SSD built-in, but it can drive an
SSD. It also has a relay that can handle 240v @ 3 amps.

Tony

> Oh, and I should mention it doesn't have a SSD built-in, but it can drive

an

And I guess only a very few can do profiles with dwell times (think re-flow oven soak time) or do that all do that?


Regards,
David Partridge


-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of Tony Smith
Sent: 13 March 2011 14:45
To: Homebrew_PCBs@yahoogroups.com
Subject: RE: [Homebrew_PCBs] WTB: PID temperature controller

> Oh, and I should mention it doesn't have a SSD built-in, but it can
> drive

an

> SSD.

Sigh. That's SSR (Solid State Relay), not SSD (Solid State Drive).

You knew what I meant. Been fiddling with laptops too much, I think.

Tony



------------------------------------

Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links

Tony,
You wrote, "I figure I can do it by monitoring the heater, and when it
switches off for the first time use that to start the timer."

No, that won't work.

Any decent PID controller properly set up will start to cycle as it
approaches the setpoint temperature. That cycling point is controlled
by the need to decrease the input energy to the heater in order to not
overshoot the temperature significantly. Optimum would be a
proportional, phase controlled SSR, but these generate more RFI, require
an analog input that brings in the need for scaling in the interface and
cost more per amp controlled. In practice the time constant of the
average application is so long, simply switching the SSR on and off for
tenths and seconds at a time is sufficient. But it's important to keep
in mind that the cycling start point varies according to all the
variables that include among others, input line voltage, heater
apparatus time constant, PID damping setting, and ambient temperature
(heat loss) among others. This cycling starts minutes in advance on just
a simple hot plate that I built a controller for using a controller I
got on Ebay a few years ago. I just searched Ebay using "digital
temperature controller" and the first item for $39 looks to be the same
one I used. I had an SSR I used, but multi-amp SSR's from MPJA
Electronics are available for $5 to $8. I built the whole thing into a
small plastic electrical box from Home Depot along with a duplex
receptacle. That way I can plug in a hot plate, electric skillet or
some other heater with ease. A great feature is that this controller
can self-tune. That saves a lot of time. Tuning a PID can be a long,
tedious process if tried by hit or miss. The controller is started,
allowed to heat up. It internally measures how long it took, and the
amount of overshoot and time to return back to the setpoint. After that
it internally sets the constants needed, loads them to flash memory so
powering the unit down doesn't lose the information, and does a great
job. It would be nice if there were a way to externally control the
setpoint then the idea of thermal profile reflow would be possible, but
that controller would be quite a bit more money.

I've seen hacker solutions where a uP is used to decode the display
signals to the device to be controlled (such as this temperature
controller) Then input to the control switches to change its
settings. However the level of that task is almost the same as just
starting from scratch and making PID controller with the chips you
mentioned.

Regards,
Charles R. Patton

> And I guess only a very few can do profiles with dwell times (think

re-flow

> Tony,
> You wrote, "I figure I can do it by monitoring the heater, and when it
> switches off for the first time use that to start the timer."
>
> No, that won't work.
>
> Any decent PID controller properly set up will start to cycle as it
> approaches the setpoint temperature. That cycling point is controlled

Yeah, I wasn't optimistic, I figured I might be pretty close to the target
temperature when the first cycle happened. If it happens minutes out
that'll be a problem. The timers I have only need a single pulse to start
(ie the heater changing state), so I guess I'll need a new plan.

I did find a page that talked about how you can reverse the alarm setting so
that it switches off when the temperature falls within the target zone. If
true then that has promise (and only needs a single NPN transistor).

The OP might find this interesting -
http://www.neufeld.newton.ks.us/electronics/?p=537. The display is attached
by cable to the rest of the electronics, so it can be shoehorned into a
shallower (if wider) box.

These auto-tune as well.

Tony

Well, my temperature controllers turned up after getting diverted by
Customs. I wonder if dope growers use these.

They're cute little things, and very simple to set up, I had it controlling
the kettle in about 10 minutes (5 of that was finding bits).

Interestingly they're made in Japan, which would explain why the manual was
in Japanese. (Of maybe the Chinese are imitating another Japanese company,
like they did with NEC as while back.)

There seems to be about a million variations of these things, the model I
have is the 'RKC Rex-C100', second from the bottom on this page -
http://www.rkcinst.co.jp/english/product/single2-e.htm

The fun doesn't stop there though. For that model certain options can get
locked or be missing, for example they can accept a wide variety of sensors,
but for mine it is locked to K-type thermocouples up to 400C. Various
manuals I'd found online explained how to set that option, it confused me a
bit as mine didn't have it but then I found the correct manual.

I also solved my problem of how to trigger a timer when the correct
temperature is reached. You can do this with the alarms; you set a low &
high point, so if your target is 150C, you set the low at say 148 & high at
152, and an alarm triggers if it falls outside this range. Turns out you
can set a 'band' alarm, which will trigger when inside the range, exactly
what I wanted. Mine, however, is missing the option to choose the type of
alarm, and is locked to 'high' only. Bugger. I need the REX-C100FK02-M*DN,
not the REX-C100FK02-M*AN, although why they couldn't have it set in
software is beyond me.

Although similar to this one -
http://www.neufeld.newton.ks.us/electronics/?p=537, you can see the
differences when dismantled. Instead of a switchmode power supply, it has
the old style transformer. Wires between the boards are soldered, not
plugs. While the power supply board is separate, the logic board is
soldered to the display, so it can't be easily re-arrange to fit a shallow
hole. All that saves a few cents here & there. At least without the
switchmode supply I might avoid the infamous 'capacitor plague' that
everything else I own has suffered from.

I've no idea why they're on eBay so cheap, but there's no way you can make
something like this yourself for the same price.

Reflow oven builders will find this -
http://www.rkcinst.co.jp/english/pf900/index.html - interesting. Very
interesting if it's cheap.

Tony

--- In Homebrew_PCBs@yahoogroups.com, "David C. Partridge" <david.partridge@...> wrote: