[SS2S-Main] Re: temperature controller with arduino

  • From: Tim young <tyoung489@xxxxxxxxx>
  • To: "sugarshot@xxxxxxxxxxxxx" <sugarshot@xxxxxxxxxxxxx>
  • Date: Mon, 30 Jun 2014 11:00:38 -0700

My best advice is to use the BCS-460. This will give you everything you
originally wanted in the controller.

If that's not possible your existing PID will work for providing the
temperature control. By control I mean it will sense, via your Type-K
thermocouple, the temperature at the "tip" of the probe & provide this
signal to the controller. The controller will provide an output signal to
the heating device.  The PID feedback loop in the controller will monitor
the sensed temp compared to the set point temp and adjust the output so
that you don't radically overshoot the set point. It will then maintain the
set point temp within the accuracy of the heating "System".  I don't know
if your REX-C700 PID has any built in programming abilities that would
allow you to program a temperature curve some of the low cost one do but
most don't.

Your controller can not directly handle a large output amperage so the
output signal is normally wired to a SSR Solid State Relay. Most PID
controllers can't directly control the heater. You would also need to use
SSR(s) with the BCS-460.

The PID's signal will modulate the electric heating element. Most PID could
also use an electrical mechanical contactor (relay) but the this is not
ideal for several reasons.  35 years ago SSR were just starting improve in
reliability (you had a 50/50 chance of them lasting 1-year) but they were
high priced.  Today's SSR's have low price & good reliability.

Since you only have 1 sense point with your existing PID ( the BCS-460 has
4) you will not be able to sense both the oven temp and the product temp
with the same thermocouple. I expect that there will not be a point on the
nosecone where you could insert the tip of the thermocouple into the
construction to sense it's temperature during the curing process.  I would
recommend that you make some separate pieces that are representative of the
construction that you could insert the tip of the thermocouple. While this
will not be an exact indication of the temperature of the nosecone it will
be close enough. Again sensing the oven air temperature will not be
sufficient to properly monitor the temperature of the nosecone.

If you plan on using a hair dryer (or any consumer heater device) you will
probably need to remove the high temperature cut-off device.  Also the fan
motors in these devices expect to see 100% ambient (cool) air, not recycled
heated air.  Normally in ovens the fan motors are located outside of the
heated space with only the fan blade or wheel actually seeing the heated

Convection ovens rely upon high velocity air (high hundreds to thousands of
feet per minute velocity) to both maintain uniform oven temperature & to
eliminate the insulating boundary layer of air at the surface of the part.
When this boundary layer is eliminated the thermal energy in the air is
transferred to the part much more efficiently.  Therefore the air
temperature in the oven needent be a great deal higher then the desired
temperature of the part.

Unless you plan on doing many curing runs it may be worth a few phone calls
or emails to local Universities or Business to see if they will donate some
oven time to this project.

*Solid State Relay *

*SSR-40DA 40A /250V W I/O 3-32VDC/24-380VAC & Heat Sink*

*US $8.73*


On Mon, Jun 30, 2014 at 7:08 AM, James Fackert <jimfackert@xxxxxxxxx> wrote:

> mine too. an hour or two learning to program a $50 temp controller (maybe
> $100 with multiple ramps and usb with pc based programmer )
> is much cheaper than the hours and learning curve to program and to
> properly interface an arduino that will cost at least $100 with box and
> interface circuitry.
> jim fackert
> On Jun 30, 2014 9:17 AM, "Vicente Alvero Zambrano" <
> vicente_alvero_14@xxxxxxxxxxx> wrote:
>> Your opinion is to use the existing PID device?
>> > Subject: [SS2S-Main] Re: temperature controller with arduino
>> > From: waaslandwolf@xxxxxxxxx
>> > Date: Mon, 30 Jun 2014 14:21:03 +0200
>> > To: sugarshot@xxxxxxxxxxxxx
>> >
>> > I agree with Peter. Trying to save a mere 180$ by developing a solution
>> that already exists isn't good use of resources.
>> >
>> > > Op 30-jun.-2014 om 00:52 heeft Peter Johansson <
>> rockets4kids@xxxxxxxxx> het volgende geschreven:
>> > >
>> > > On Sun, Jun 29, 2014 at 6:36 PM, Vicente Alvero Zambrano
>> > > <vicente_alvero_14@xxxxxxxxxxx> wrote:
>> > >
>> > >> My idea is to use an old oven heater like the picture.
>> > >> With respect to the PID controller, maybe it is cheaper to do it
>> manually,
>> > >> without writing code.
>> > >
>> > > One option to consider -- and an advantage to going with a homebrew
>> > > solution -- is to simply read a configuration file containing the
>> > > temperature profile and PID tunings over over the serial port.
>> > >
>> > > This way you get the maximal possible control with the minimal
>> > > hardware cost and minimal software development time.
>> > >
>> > > -p.
>> > >
>> >

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