I've searched and searched and I'm yet to find a relatively cheap dual setpoint pid controller, they are all in the $200+ range. I realize I can use the alarm output for the steam control but was wondering if anyone knows of a cheap Chinese model that actually has a true dual setpoint?
I have not found a cheap PID with 2 PID controlled points. You would not want steam PID controlled as it would be slower to get there. Alarm is adequate, probably best, for steam clicking on and off 1 degree apart on the alarm. I offer that not knowing your use or machine, so YMMV.
I do not see your location, but I found Auber inexpensive enough for a PID. Many of the Chinese generics are similar but instructions may be difficult.
By dual setpoint, do you mean two separate control loops (i.e. two sensors, two sets of outputs)? Or a unit that stores two setpoints and selects one of them based on some external event?
If the application is for steam mode on a SBDU espresso machine, I agree with D4F that simple ON/OFF control at the steam setpoint, such as is provided by an alarm output, works better than PID control.
If you truly need PID control at selectable setpoints, I think maybe Delta offers a 1/16DIN controller that can sense an external event (like closing a switch). Otherwise, look on eBay for a used Watlow 96A1-xxxx-xxxx controller.
By dual setpoint, do you mean two separate control loops (i.e. two sensors, two sets of outputs)? Or a unit that stores two setpoints and selects one of them based on some external event?
a used Watlow 96 series controller is a great choice it is a reliable controller and has many options to pick from it you have the patient, you can buy one on eBay for less then $50
By dual setpoint, do you mean two separate control loops (i.e. two sensors, two sets of outputs)? Or a unit that stores two setpoints and selects one of them based on some external event?
If the application is for steam mode on a SBDU espresso machine, I agree with D4F that simple ON/OFF control at the steam setpoint, such as is provided by an alarm output, works better than PID control.
If you truly need PID control at selectable setpoints, I think maybe Delta offers a 1/16DIN controller that can sense an external event (like closing a switch). Otherwise, look on eBay for a used Watlow 96A1-xxxx-xxxx controller.
Yes I was just looking for dual setpoint that can be triggered by external event, such as shorting a few pins. Yes the idea was to get a better steam control on my single boiler machine (Silvia). I guess I'll just stick with the alarm output, what I don't like about that is that I either need an alternative low voltage setup or a 2nd SSR.
I was also in that situation and finally settled with the second SSR (AC SSR, which are harder to find actually). It seems the auber PID with steam control actually uses a tweaked controller to control the steam so you may wish to look at that option (I'm not sure if they use 1 or 2 SSRs).
Anyhow, the second SSR setup was very easy to install, and I believe it would be the same if you used a power adapter instead. Its just a matter of not cluttering the machine too much, but its the cheapest option I could find.
Yes I was just looking for dual setpoint that can be triggered by external event, such as shorting a few pins. Yes the idea was to get a better steam control on my single boiler machine (Silvia). I guess I'll just stick with the alarm output, what I don't like about that is that I either need an alternative low voltage setup or a 2nd SSR.
The Auber kit uses a proprietary version of the same PID and activates the SSR through the alarm function without a DC source or second SSR if I have read the instructions correctly. Try email to Auber. IIRC, he has an AC to DC converter/switcher added or activated in the PID.
I did DIY and used the voltage source, in fact I have 2 DC sources inside the machine and controlled by the machine switches (external events), and 3 SSR inputs and diodes, like Skene.
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