I disagree. Thermocouples are much more reliable, and the cost is much cheaper compared to probes, other than the added costs of additional amplifiers required. When I get a chance (a bit busy now with moving back to the US), I'll try to see if I can draw up a board and get a few samples from OSH Park.
Heatermeter Aux. Thermocouple And two probe board V6.1(Final Version)
- Thread starter John Bostwick
- Start date
I disagree. Thermocouples are much more reliable, and the cost is much cheaper compared to probes, other than the added costs of additional amplifiers required. When I get a chance (a bit busy now with moving back to the US), I'll try to see if I can draw up a board and get a few samples from OSH Park.
John Bostwick
TVWBB Wizard
You won't get more then 3 thermocouples using the cat5 cable. If you were to remove the ground connection that is used just for the amp and probes, and used the same ground as the blower and servo, then you will end up with alot of noise and Temps being off.
You could use a what I had used in a previous project, a 9 pin DIN connector and cable. The connector is a tad smaller then a RJ45 connector. That would give you the extra wire for another thermocouple. Then it would a simple as making a small auxillary board with 4 thermocouple circuits along with a blower and servo connector. It would add about $40 to a heatermeter, not counting the OSH cost
Haven't thought of all that, John. Seems like you have it figured out. Maybe I'll spend my time on other ventures. Thanks for the heads up.
I am in the process of putting together a HM 4.2.4 and the Aux board. Almost done, just waiting for the newark thermocouple jacks to be back in stock. I have a couple questions that I can't seem to find the answers to. Wether or not I need to populate the thermocouple parts on the HM board or not if I have them on the Aux board. Also, where do I need to modify the HM board to use the remote probes over the cat5?
RalphTrimble
TVWBB Diamond Member
You do not need to build up the SMD TC amp on the HM board if you have the Aux TC board, you can only use one at a time anyways. You CAN populate them both but would have to rig up your HM to switch between them. I have them both but never really switch over to the onboard TC because the Aux board is more convenient and has been very reliable.
As for the wiring on the HM board, shoot me an email or PM and I will help you out with that...
As for the wiring on the HM board, shoot me an email or PM and I will help you out with that...
John Bostwick
TVWBB Wizard
To modify the HM for the two probes you connect
Wires to pins 1 and 2 of the rj45 jack then the other end of the wires go to the 5 pads that are under the probe jacks. The first pad(from the thermocouple circuit) is ground, then pit, 1, 2, 3.
Its been a long time since I had to eire boards up with wires, I use modified HM boards that have a place for a switch and all the connections already on the board
John Bostwick
TVWBB Wizard
I hadn't made the boards public, as I use them for my builds, to make things more rebust for those people that have no knowledge of soldering. I wanted to eliminate all possible weak points to using the adapter boards.
John
I recently built one of these, but am struggling to get it to work. I built A HM 4.3, which operates as expected. When I connect the RDTC board with a TC and a temp probe, nothing changes, it still does not see any connected probes. Was I supposed to modify my HM to support this board?
John Bostwick
TVWBB Wizard
Yes, the HM does need to be modified. It's will need extra wires and a switch added to the board. The boards I personally make are pre-modified to work with the adapter board, and have a spot for wiring up a switch. You will need to follow the 4.2 version customized, which I don't have access to atm.
Ah, thats good to know. I'll start digging through the forums. Hopefully its an easy mod to locate and implement.
James Davies
New member
This looks very interesting!
What output is there on the CAT5 cable? If I wanted to write my own software just using a Raspberry Pi and this, how feasible/practical is it to read the temps and drive the servo/blower without the HM? Is it possible to wire up the CAT5 on the pi end to the GPIO so it can all be controlled easily?
I have an Adafruit thermocouple adapter that i was planning to use but this seems like a much better board if I can get everything in one!
What output is there on the CAT5 cable? If I wanted to write my own software just using a Raspberry Pi and this, how feasible/practical is it to read the temps and drive the servo/blower without the HM? Is it possible to wire up the CAT5 on the pi end to the GPIO so it can all be controlled easily?
I have an Adafruit thermocouple adapter that i was planning to use but this seems like a much better board if I can get everything in one!
Steve_M
TVWBB Guru
It's not very feasible at all. The RasPi doesn't have any analog I/O, which you need to read the temp sensors. You'd also need a blower driver, etc. The HM board is really doing all of the work and the RasPi extends the functionality of the HM board by giving it a web based interface as well as the alerting. This is why you can run the HM without a RasPi, but not the other way around.
John Bostwick
TVWBB Wizard
Yep that is correct diagram. It's not setup for the 4.3, but the 4.3 has made it easier to wire the rj45 jack, as it has solder points for the 4 unused wires
Hopefully my last post on the subject. It looks like I need to make the following changes:
1 - Connect RJ45 Pin 8 to GND
2 - Connect RJ45 Pin 7 to top pole of double throw switch
3 - Connect the lone 100K resistor on HM 4.3 (opposed to one of the 100K resistors aligned in a bank) to middle pole of switch
4 - Connect bottom pole of switch to vacant 100K resistor hole
5 - Connect RJ45 Pin 1 to J2 PROBE 1
6 - Connect RJ45 Pin 2 to J2 PROBE 2
HM4.3 Board
1 - Connect RJ45 Pin 8 to GND
2 - Connect RJ45 Pin 7 to top pole of double throw switch
3 - Connect the lone 100K resistor on HM 4.3 (opposed to one of the 100K resistors aligned in a bank) to middle pole of switch
4 - Connect bottom pole of switch to vacant 100K resistor hole
5 - Connect RJ45 Pin 1 to J2 PROBE 1
6 - Connect RJ45 Pin 2 to J2 PROBE 2
HM4.3 Board
John Bostwick
TVWBB Wizard
Sounds about right.
John Parkinson
New member
Hi,
Is there a schematic available for this board? Just trying to debug a servo problem
Is there a schematic available for this board? Just trying to debug a servo problem