[time-nuts] Tbolt temperature Control

[WarrenS]

This can also be made to work on the TBolt units that have the 1/2 deg course Temp sensor. 
The control loop gets a bit trickier, but it can hold the Temp very close at one its course transitions points. 
This would come in handy for those not wanting to change their sensor to the high resolution type.

Another useful feature to add to a completely independent micro controller so that it needs no other inputs is to have its program smart enough to automatically and slowly readjust its set point control Temperature to just above the highest day to day Peak temp it sees. Needs no extra inputs, It just needs to monitor its own PID loop to see if it even comes out of control due to excess temp.  

Note you do not have to pass anything thru or output any RS232, just the ONE bit  if the micro is going to control the temp out bit.
It just needs to pick up the Tbolt output data in parallel and capture the Temp info.
If the micro is not doing the Temp control then there is no need to have the extra micro.

ws
********
>Don Latham djl at montana.com 
>Wed Aug 26 17:38:21 UTC 2009 

>Heck, Warren, I'll put it on the line :-). Use a very simple and cheap
>processor such as a Picaxe, pass the rs232 through it to Lady Heather etc,
>and capture  the temperature, using it appropriately. Should work nicely
>and keeps the temp control local. Even put a little LED on it to indicate
>state.
>Don
**************
> TBolt Nuts
>
> To keep My TBolt's temperature constant so that the environment has
> minimal effect on it,
> I use an aquarium temperature controller (modified to have low hysteresis)
> connected to a low wattage light bulb, placed in a box with the TBolt.
> It works OK and keeps the TBolt's temperature constant to well under 1
> deg.
> To do it better and make it  more hi tech,
> I'd like to have the temperature control based on the TBolt's internal
> sensor.
>
> What I have found works well is to use the TBolt's own RS232 temperature
> sensor output data,
> and with a modified PID type of S/W controller, turn an external heater
> &/or cooler on off.
>
> The heater can be an appropriate power resistor or transistor dissipating
> up to about 4 Watt,
> mounted to the TBolt case. What I use to cool the Tbolt up to 5 deg C, is
> a small fan blowing
> at a heatsink mounted on the top of the TBolt's case.
> Turning the fan on & off with a S/W driven switch, can be used to keep the
> TBolt's
> internal temperature very constant over a limited external temperature
> range.
> A standard PC chip fan & heatsink may be OK, if it does not add Phase
> noise due to it's vibration.
>
> Because of the long time constant and slow response of the internal
> temperature sensor,
> a single digital on-off bit, updated at a max rate of once per second
> works great for control,
> No analog needed. To keep the hardware and interface circuit simple,
> I'd like to be able to use one of the unused standard RS232 outputs,
> such as RTS, CTS, DSR, DTR  as the heater/cooler control bit(s).
> This is no problem when doing this in a DOS program or from an added
> microprocessor
> that monitors the Tbolt's  communications,  But the question is,
> can it be done in Windows in such a way that a modified existing program
> such as
> Lady Heather or Tbolt monitor could control an already existing readily
> available digital bit?
>
> Being a control person, Doing a software algorithm is the easy part.
> Making Windows do any kind of non standard I/O control, is way above my
> capability.
> I'd like to get feedback from a Windows expert if there is a simple way to
> control an existing Digital bit
> that would be available on a PC being used in a typical setup that is used
> to monitor the Tbolt.
> One way I have heard suggested is to use the sound card output,
> but I'd like to keep it even simpler than that, Any suggestions?
>
> If anyone is interested in developing a program to make an existing stand
> alone micro
> or basic stamp to include this function they can contact me off line for
> some sugestions.
>
> Thanks,
> ws
> ******************