Terminal boards for WebControl
- Thread starter rossw
- Start date
jzsjr said:
Hi Jim, not a problem. Which boards did you actually want?
The base V2 kit is the board with amplifier pre-soldered, terminals, 20-turn trimpots and connectors.
The V2 with regulator is the same board, but with TO-220 regulator and heatsink included. (Can run the webcontrol comfortably off a 12V supply)
The V2 PLUS board has space for sockets and 3 pins for wire jumpers, the purpose is to make a convenient way to connect multiple temperature probes to a board.
The PLUS board can have the regulator fitted or not, depending on your needs. (Regulator can always be fitted later if needs change)
If you can let me know ASAP, I'll try to get them in the post today.
Efried
Active Member
Efried said:
Without pressing too much what might we expect for the WC32?
yes:
- PWM based 4 wire fan control logic
rather yes:
- communication stack purging command
- protected code
- restarting command
- allowing comment lines in the PLC
- energy saving snooze mode
no:
- self updating
- secure email account data
- serial AT commands for a wifi piggyback
- adding ELSE as command
- RAM status output
- 0.x default IP address range
- 12 bit AD
- acknowledgement reply after receiving webset commands successfully
CAI_Support
Senior Member
Hi Efried,
Do you mind to start another thread discussion for WC32 instead of posting the WC32 in terminal board discussion topic? Since many users want to follow the thread of discussion from different topics, it will be easier for other viewers to follow.
If you send us email directly, we can email you the user guide for WC32, which has spec in it to answer many of your above questions. Then for unanswered questions, please start another discussion topics. Thanks for pushing us to make better products.
Do you mind to start another thread discussion for WC32 instead of posting the WC32 in terminal board discussion topic? Since many users want to follow the thread of discussion from different topics, it will be easier for other viewers to follow.
If you send us email directly, we can email you the user guide for WC32, which has spec in it to answer many of your above questions. Then for unanswered questions, please start another discussion topics. Thanks for pushing us to make better products.
Ross,
I'm just a little confused about the power supply of the WC8 and the WebAmpV2 boards (having just purchased 2 with the regulator installed).
When you say "The V2 with regulator is the same board, but with TO-220 regulator and heatsink included. (Can run the webcontrol comfortably off a 12V supply)" do you mean that the WC8 will be powered from the WebAmp board negating the need to connect a power supply to the WC8 itself? Or does the WC8 still need to be powered using the screw terminals?
In my application I want measure pool pH, ORP and filter pressure using the Phidgets ORP/pH adaptor (http://www.phidgets.com/products.php?product_id=1130) and a 0-5v pressure transducer. They all need +5v DC supply and give an output from 0-5v depending on readings. I think they will collectively draw more current than the WC8 +5 (20mA on pin 13 on AUX) can supply. So I plan to use your daughter board to power the sensors.
If I supply +9v to +V on the WebAmp (with regulator) will that power the WC8 and allow me use the +5 screw terminal on the WebAmp to power the adaptors and pressure sensor? Will supplying +9v to the amplifier (via pin4) still give me a reliable 0-5v input/output?
And what capacitor & resistor do you suggest to use for RC input filtering in this application?
Many thanks, Marty.
I'm just a little confused about the power supply of the WC8 and the WebAmpV2 boards (having just purchased 2 with the regulator installed).
When you say "The V2 with regulator is the same board, but with TO-220 regulator and heatsink included. (Can run the webcontrol comfortably off a 12V supply)" do you mean that the WC8 will be powered from the WebAmp board negating the need to connect a power supply to the WC8 itself? Or does the WC8 still need to be powered using the screw terminals?
In my application I want measure pool pH, ORP and filter pressure using the Phidgets ORP/pH adaptor (http://www.phidgets.com/products.php?product_id=1130) and a 0-5v pressure transducer. They all need +5v DC supply and give an output from 0-5v depending on readings. I think they will collectively draw more current than the WC8 +5 (20mA on pin 13 on AUX) can supply. So I plan to use your daughter board to power the sensors.
If I supply +9v to +V on the WebAmp (with regulator) will that power the WC8 and allow me use the +5 screw terminal on the WebAmp to power the adaptors and pressure sensor? Will supplying +9v to the amplifier (via pin4) still give me a reliable 0-5v input/output?
And what capacitor & resistor do you suggest to use for RC input filtering in this application?
Many thanks, Marty.
mminehan said:
Correct. You can connect +12V to the terminal board, the regulator on the terminal board will power the WC8 without you having to put anything in its power terminals.
mminehan said:
The terminal board has a +5V terminal at one end, and a Gnd terminal at the other end of the TTL input connector.
You can power your sensors from these two pins.
mminehan said:
+9V is not really enough. The WC8 analog input is 0-10V. The LM2902 amplifier can only drive to within about 1.5V of the + rail, so in order to get 10V (full scale) out, you really need at least 11.5V input.
If you're prepared to have a smaller input range, thats fine.
mminehan said:
Without knowing what the drive ability of your various sensors are, it's almost impossible to guess. The pressure transducer is probably not bad, and you can probably get by with even a 100nF cap across the input. I'll have a look at your link shortly and see if I can make an intelligent guess!
EDIT: Well, I looked at their boards. There is no indication whatsoever what the output signal is, either voltage or drive capability. No circuit diagram, nothing. The boards they suggest interfacing to don't have any real specs either, although they do describe an input that may or may not be indicative of their A/D inputs. If it is, they're driving about 900 k, but they go to great lengths to warn of problems with high impedance sources.
Assuming it IS that input, my board has an input impedance that is high enough to be insignificant in this application.
Their board, running from 5V, is unlikely to output more than 0-5V, and quite possibly 0-1V. Either way, my board has plenty of adjustment in gain to work with either. 0-5V input with a gain of 2 will give you 0-10V out - perfect for WC8. If it's 0-1V, then you can just wind the gain up a bit with the trimpots on my board.
Ross,
Thanks for the prompt reply. I'm looking forward to getting the boards. I have a basic understanding of circuits. Great to read the WC8 can be powered from your board. I just PoE splitters to power the WC8 at present, and these can be set to 5, 9 or 12v (http://global.level1.com/PoE-Splitter/POS-1002/p-2022.htm). So getting a 12v supply is no problem.
An ORP probe outputs a reading in the range of 0 to 1000mV depending on the specs (some go to 2000mV). So that will be relatively simple to interface to your board and adjust the gain accordingly.
But the pH probe is a little trickier for me to understand how to configure with your board. They have an output range of -600mV to +600mV with pH 7 being about 0mV. That's kind of why I bought the Phidgets boards as I am not smart enough to work out how to apply an offset to bring the output into a positive only range (I.e. convert -600 to +600mV to something like 0 to 10V....offset and then amplify).
I have come across a few other posts on various forums on pool ORP and pH measuring in home automation. It seems to be a not uncommon question. But none have been very definitive and a few have lead to the Phidgets boards. But I'm having mixed results with these in combination with the WC8 (bouncing and noise).
Thanks, Marty.
Thanks for the prompt reply. I'm looking forward to getting the boards. I have a basic understanding of circuits. Great to read the WC8 can be powered from your board. I just PoE splitters to power the WC8 at present, and these can be set to 5, 9 or 12v (http://global.level1.com/PoE-Splitter/POS-1002/p-2022.htm). So getting a 12v supply is no problem.
An ORP probe outputs a reading in the range of 0 to 1000mV depending on the specs (some go to 2000mV). So that will be relatively simple to interface to your board and adjust the gain accordingly.
But the pH probe is a little trickier for me to understand how to configure with your board. They have an output range of -600mV to +600mV with pH 7 being about 0mV. That's kind of why I bought the Phidgets boards as I am not smart enough to work out how to apply an offset to bring the output into a positive only range (I.e. convert -600 to +600mV to something like 0 to 10V....offset and then amplify).
I have come across a few other posts on various forums on pool ORP and pH measuring in home automation. It seems to be a not uncommon question. But none have been very definitive and a few have lead to the Phidgets boards. But I'm having mixed results with these in combination with the WC8 (bouncing and noise).
Thanks, Marty.
CAI_Support
Senior Member
If adding a 600mV bias, the pH7 will be 600mV, and range of the sensor will be 0mV to 1.2V. Without amplifier, the pH reading is not only small portion of the whole reading range, its impedance is also very high. With amplifier, it can be 10 times more accurate for the small voltage, you could actually get 1pH/1V, if properly tuned for the range you want to measure. Since most pool will not have pH0 or pH14, rather maybe 2pH change max, the actual measurement range required is much smaller.
mminehan said:
Shipped yesterday by airmail, you should have them soon.
mminehan said:
OK, here's what I would suggest.
This basic circuit:
On one channel of my amplifier/terminal board, remove the trimpot and replace it with a 2K2 resistor + 22K resistor for R1 and Rf (the feedback circuit).
V1 will be ground, so the gain is set to 10.
On the input "component" part, add another two resistors, 2K2 for R1 (V2 will be the input from the pH sensor), and a 22K to the +5V rail, available easily on the terminal board itself. In this configuration, the input and output voltages will be:
V2: -0.6V Vout = 0V (clamped)
V2: -0.5V Vout = 0V
V2: -0.4V Vout = 1V
V2: -0.3V Vout = 2V
V2: -0.2V Vout = 3V
V2: -0.1V Vout = 4V
V2: 0.0V Vout = 5V
V2: 0.1V Vout = 6V
V2: 0.2V Vout = 7V
V2: 0.3V Vout = 8V
V2: 0.4V Vout = 9V
V2: 0.5V Vout = 10V
V2: 0.6V Vout = 11V (probably clamped to 10.5V, depends on supply)
This will give you a nice, linear 1V/pH into the webcontrol board, with 5V (50%) being pH7.
The circuit for my board is http://webcontrol.rossw.net/WebAmpV2/webampv2-schematic.pdf
Hi Ross,
I'm not having much luck with the pH or ORP probes connected directly to the boards (with the mod suggested above). I think the problem is they are very high impedance probes (50-500 megaohm) and have very low currents. I can read the output directly from the probe with a digital multimeter, but not with the webamp board.
Looking online at pH probe amplifier circuits the op amps need a very low input bias (e.g. TL082 as opposed to the LM2902).
I'll have to look at using a seperate pH amplifier circuit and output that to the webamp board.
Not as simple as I had hoped.
Marty
I'm not having much luck with the pH or ORP probes connected directly to the boards (with the mod suggested above). I think the problem is they are very high impedance probes (50-500 megaohm) and have very low currents. I can read the output directly from the probe with a digital multimeter, but not with the webamp board.
Looking online at pH probe amplifier circuits the op amps need a very low input bias (e.g. TL082 as opposed to the LM2902).
I'll have to look at using a seperate pH amplifier circuit and output that to the webamp board.
Not as simple as I had hoped.
Marty
CAI_Support
Senior Member
for amplifier works reliably with pH or ORP probes, the input impedance needs to be 10^12 Ohm. MCP6004 can have input impedance up to 10^13Ohm, so that properly adjust the gain divider resistors would work.
CAI_Support said:
I do offer these boards with MCP6004 opamp, but only when specifically asked, as there are some significant catches with the WC8.
The MCP6004 has an absolute maximum supply voltage of 6V.
The WC8 analog input is 0-10V unless you start messing with its input resistors (which may void warranty)
For those who are happy to accept an input range of 0-5V only (makes it in effect only a 9-bit ADC), I'll fit MCP6004 instead of LM2902. This also means the regulator won't be fitted (or used), and a jumper placed on the terminal board from its input to output. Obviously, the only regulator then is the one on the WC8, so operation from 9V is preferable to reduce overheating.
Marty: I'm sorry, I mis-interpreted your comment. I thought from your earlier comment that you had other boards that were giving you the +/- 600mV, and presumed that they would have had a much higher drive capability.
The boards I sent you can be easily modified to use MCP6004 if you wish, although my boards do not have guard traces and wide spaces to maximise input impedance. If you clean them really well and keep them dry, it might be enough... just.
CAI_Support
Senior Member
Ross, can the board fit with LMP7704? that is less than pA input bias amps. If you ask you local TI sales office, they might send you couple sample chips.
