Heatermeter Aux. Thermocouple And two probe board V6.1(Final Version)

John Bostwick

TVWBB Wizard
Heatermeter Aux. Thermocouple And two probe board V6.2

Well, its been through a lot of changes and Ralph and I believe we have finally found a version of the board that has everything where it needs to be and works the way its suppose to.

This board has a Thermocouple amp and jack and two probes along with connections for the blower and servo that can be connected to a Cat5 cable and the Heatermeter. The TC amp can be either be used at 3.3v or 5V by adding a 3.3 regulator, if running at 5v then you can jumper it.

Also, you can add the ability to use a reference voltage on the thermocouple amp that will let the thermocouple read temperatures below zero. If you don't need this ability, then it to can be bypassed and the TC will work the same as the one on the Heatermeter.

To order the board

OSH Park


The Mouser Components

Newark Thermocouple jack

If not using The Ref. voltage then the following are not needed

OP777ARZ
100k Trimmer-Part # 652-3361P-1-104GLF
C3-.1u cap
R3-1M resistor

If not using a 3.3v Regulator, the following are not needed

C1, C2 - .1u cap
MCP1700T 3.3v Regulator

This board also uses a single locking header for attaching a blower and servo, although, it to can be omitted from the board and alternate attaching headers can be used. Its nice having a simple secure connection if you are using a servo and blower.

This board does not add to the total Thermocouples or probes the Heatermeter can use. This only extends the TC and probe connections to the end of a Cat5 cable verified upto 50ft.

TOP

Bottom

Updated to V.6.2
Moved the probe two 1mm closer to the TC jack to help with Thermowork probes. Also, moved some parts around to help with soldering. If using the TC jack hold down staple. Solder it after placing the probe jacks, as it may cause interference with placement from solder.

Update 6.20.2015
Moved a few components and component names to better tell them apart

Updated 8.12.2015
-Tented vias(no more visible vias to accidently solder)
-Added an alternate Pit 2.5mm jack, If you don't want to solder SMD parts they can be eliminated and you can use a regular thermistor for the Pit probe.
 
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Dan Francis

TVWBB Fan
Hi John, Just built a version 5 TC Amp and have a question on the 2 sets of jumper pads. I installed all components so assume by what is written above I don't jumper the 3.3v pads, the others say something about reference ground I believe. I'm not sure by what is written above when you jumper or not these pads. Thanks.

Edit. Rereading a few times I think since I have the trimmer I don't jumper the reference pads either. My trimmer doesn't seem to have any effect so maybe I need to recheck my solder job.
 
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John Bostwick

TVWBB Wizard
The two jumper pads should only be solder if you will be bypassing the opamp circuit. Also, im not sure of when you got your parts but we changed opamps to, i believe from a opamp77(?)to a opamp777 or whats in the parts list now. The reason was when i had tested it, i could not get temperature below 300°.

Also, the trimmer should be a 100k, i beleive, but if you have a larger value, it should just give you more movement to the temperature. Regardless, of opamp or trimmer, you should see movement in temperature.

Once, im home i can help a little more, or if Ralph can also, he would be more in the know when it comes to figuring out opamp and trimmer issues.
 

Dan Francis

TVWBB Fan
The two jumper pads should only be solder if you will be bypassing the opamp circuit. Also, im not sure of when you got your parts but we changed opamps to, i believe from a opamp77(?)to a opamp777 or whats in the parts list now. The reason was when i had tested it, i could not get temperature below 300°.

Also, the trimmer should be a 100k, i beleive, but if you have a larger value, it should just give you more movement to the temperature. Regardless, of opamp or trimmer, you should see movement in temperature.

Once, im home i can help a little more, or if Ralph can also, he would be more in the know when it comes to figuring out opamp and trimmer issues.
Thanks. I do have the old opamp installed but also have the 777 here. I ordered parts at two different times and didn't notice the change, will attempt to swap them out. Sounds like that should do it as my temp above 300 also. Thanks again.
 

RalphTrimble

TVWBB Diamond Member
you want the more expensive 777 op amp. John also had a problem getting the offset circuit to work with the cheaper OP07DRZ op amp, I didn't have one for testing so I haven't been able to examine what was going on. On my last parts order I did get a OP07DRZ, but I have a lot on my plate right now so I don't see me getting a chance to experiment with the circuit. Using the 777 op amp you should be golden, I've built more than a half dozen of those circuits and they all work great.
 

Dan Francis

TVWBB Fan
Tried to swap out part but burned/pulled pads off. Built new board this morning with correct 777 op amp and works perfect. Good job guys! Thanks.
 

James VanDever

New member
Hi john I just received the boards that I ordered from osh park I counted 10 capacitors and resistors(basically the same size)not counting the trimmer and received 11 from mouser so i wanted to ask about it before I got started.
 

John Bostwick

TVWBB Wizard
it should be
2 1n (1000 pF) (TC)
1 10n (0.01 uF) (TC)
3 0.1u(TC & 3.3v regulator)
2 10k(TC)
1 1k(TC)
1 1m(for opamp)

Trimmer
100k
 

Dan Francis

TVWBB Fan
Just thought I'd let you know how your TC amp is being used out there. This is a v5 in a case I printed up. I plug it into a cat5 cable I have run to my deck and snap it on a leg of the BGE with the glued on magnet. The extra jack is for a cat5 jumper to my blower/servo. Works perfect!

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DaveyR

New member
Hi John

Well i finally got life to the point that i was able to build my aux board. I didnt put in the op amp as i had the 77 or the 3v ref but it seems that the TC temp is just way off.

The food probe is reading 74 and the TC is reading 195. The strange thing is when i heat the TC the temp goes down not up.

Should i put in the other parts and order the 777 op amp ?

Thanks

Davey
 

RalphTrimble

TVWBB Diamond Member
are you working with a RDTCv6 or RDTCv6.1 board? I built a few v6 and had no problems, I built a few v6.1 and with one board I had the same problem as you are having with the TC. I had the 3.3v reg installed and the REF circuit, both of which I removed in attempt to isolate the problem, unfortunately I never was able to isolate the problem and ended up trashing the whole board. There is something about the v6.1 design that makes it harder to build, IDK if it is a via too close to a pin under the TC amp or what, but v6.1 is definitely harder to build.
 

DaveyR

New member
Hi Ralph.

It was the 6.1 version. I have ordered a new set of parts for building the other 2 boards.

Just to confirm once i have got the TC amp and the basic components i should be able to test by linking the 5v and refG jumpers correct. Then remove them and add in the Op AMP and the Voltage Reg?

Thanks
 

John Bostwick

TVWBB Wizard
Hi Ralph.

It was the 6.1 version. I have ordered a new set of parts for building the other 2 boards.

Just to confirm once i have got the TC amp and the basic components i should be able to test by linking the 5v and refG jumpers correct. Then remove them and add in the Op AMP and the Voltage Reg?

Thanks
If you install all the parts the 5v and RefG pads are not used
 

RalphTrimble

TVWBB Diamond Member
I found the v6.1 board harder to build than the v6 board.... After completely building up one that wouldn't work, and troubleshooting for an hour and never fixing it I decided to test the boards mid build myself. So with the v6.1 I generally install the TC amp, caps, resistors, 3.3vreg and the CAT5 jack, then jumper the REF gnd and plug it into a HM to test. This way I can test the tc amp without the reference circuit first, and troubleshoot it without the TC and probe jacks in the way if it doesnt work. Once the TC amp is verified I move on to the REF IC and install the jacks.
John, we had talked last week about the RDTC board, and how the the plugs on the new Thermoworks Pro probes are bigger around and wont fit side by side in the RDTC. I suggest that if we do go back and widen the space on the food probe jacks that we take a step backward and work from the v6 design instead of v6.1, because I found v6 to be easier to build. The only problem I found with V6 is the screen printing for the header was mixed up, showing the servo where the blower should be, which would be easily corrected without rerouting any of the circuits. The only other thing I would suggest you look at if you are modifying the board would be to make sure all via's are as far as possible from the chips and any solder joint really, but particularly not under the chips were solder could flow and bridge and you will never see it (I think that might be what happened to the one RDTCv6.1 board I build that was DOA)
 

DaveyR

New member
The parts should be here on Monday but i now see that i should look at ordering a new blower for the RD3 :) so i will hopefully not have issues with the new builds.

Will let people know.
 

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