The Brauduino (Matho’s Controller) Build/Advice/Question Thread

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zwitter

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Resistors for temp probes

malt junkie said:
The 4.7k resistor is already onboard there should be no need for another, though in real terms a second won't adversely affect readings.
Actually there are 2 resistors for the temp probe circuitry. The one on the board is to pull the data line high as the probe (DS18b20) has an open collector output. The other built into the socket wiring is in the positive wire in series as a current limiting device to prevent damage when plugging and unplugging the probe.

The probe is a wonderful device ans can actually be used in a 2 wire configuration and multiples can all be connected to the same pin and they then use their unique addresses to communicate. Really smart little devices.

James
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malt junkie

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zwitter said:
Resistors for temp probes


Actually there are 2 resistors for the temp probe circuitry. The one on the board is to pull the data line high as the probe (DS18b20) has an open collector output. The other built into the socket wiring is in the positive wire in series as a current limiting device to prevent damage when plugging and unplugging the probe.

The probe is a wonderful device ans can actually be used in a 2 wire configuration and multiples can all be connected to the same pin and they then use their unique addresses to communicate. Really smart little devices.

James
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Is there a reason the current limiting circuit couldn't be onboard rather than the socket wiring? As you may be aware I'm designing the wifi edition.
 

Meddo

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Hi all, I've got two of these probes and want to use the second one as a temperature monitor (readout only) for the cold side of my counterflow wort chiller since it's a great size and should be easy to install into a tri-clamp fitting. Is there an easy, no-programming-required method of getting a temperature readout from the probe? I'm happy to cut the 3.5mm plug off and replace it or wire directly into a readout device, but I'd prefer not to have to play with software for this particular job if I can avoid it.

Thanks in advance,
 

malt junkie

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The controller is only programed for ONE sensor, adding multiple sensors and being able to allocate these to specific tasks is a fair chunk of coding. If you have Lael's kit with the Atmega 2560 it has room for more code, the uno will not. The hardware is the easy bit. BrewmaniacEX (whole new board etc but will bolt into Laels kit) has multiple sensor input already coded. I know I've been promising, wrong parts and china's postage have held me back.

cheers
MJ
 

Meddo

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Thanks @malt junkie, I probably (definitely, upon re-reading it) worded that poorly though - I'm happy for the second probe to be independent of the controller, I basically just want a digital display that I can put on the probe to effectively use it as a thermometer to check visually.

Cheers,
 
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malt junkie

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K..... I have seen displays for PT100 sensors(not what we use in these controllers) on fleabay, probably the best way to go. Then you can keep the spare as a spare. If I find them I'll link.
 

Gibbo411

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I'd just like to post my interest in a wifi model once they become available.
 

malt junkie

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Thanks @malt junkie, I probably (definitely, upon re-reading it) worded that poorly though - I'm happy for the second probe to be independent of the controller, I basically just want a digital display that I can put on the probe to effectively use it as a thermometer to check visually.

Cheers,
One of these and one of these

all told with a box maybe $60 job done

ED link updated, note the sensor is 1/2" to make inline simpler
 
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zwitter

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Hi Meddo

If your probe is the one supplied with the Brauduino kit then it is a DS18b20 not a pt100

If you go to ebay and search for " 18b20 display" you will get all sorts of displays with alarms and other options. From less than $10

James
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Meddo

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Hi Meddo

If your probe is the one supplied with the Brauduino kit then it is a DS18b20 not a pt100

If you go to ebay and search for " 18b20 display" you will get all sorts of displays with alarms and other options. From less than $10

James
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That's great, thanks zwitter (and thanks @malt junkie). Using my spare probe is likely to be a better solution for me since the Pt100 probes all seem to be minimum 50mm compared to the neat stubby little thing that came with the kit, and the smaller the better for my use case (fitting to a 1.5" tri clamp end cap and mounting to the stem of one of these https://www.glaciertanks.com/product.cgi?group=6792&product=5345).

So if I got something like this - http://www.ebay.com.au/itm/Blue-Red...r-Module-Photosensitive-Control-/382144011621 - are you able to tell whether the probe would basically be plug-and-play, or would I need to remove the in-line resistor? My preference would be to keep the current probe and wiring intact and connect a 3.5mm jack to the display so that I could interchange the two probes as required.

Also does anyone remember off the top of their head what the correct hole size is for mounting the probe/thermowell?

Happy to take this to PMs if side-tracking the thread.

Thanks again,
 

zwitter

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Hi Meddo

The resistor is in the socket half of the brauduino cable.

I am reasonably sure that you could just use the harness with resistor in it and should work fine. Otherwise a socket can be bought on ebay or at Jaycar or similar and just wire that up. Just get the connections correct or the probe will die.

I think the hole was 10mm

I actually purchased a couple of the really small ones and will wire them up when they arrive.

James
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Meddo

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Hi Meddo

The resistor is in the socket half of the brauduino cable.

I am reasonably sure that you could just use the harness with resistor in it and should work fine. Otherwise a socket can be bought on ebay or at Jaycar or similar and just wire that up. Just get the connections correct or the probe will die.

I think the hole was 10mm

I actually purchased a couple of the really small ones and will wire them up when they arrive.

James
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Hey James, this got pushed to the backburner for me briefly so I haven't progressed at all, have yours arrived yet? Curious to see what you come up with.

Cheers,
 

zwitter

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Hi Meddo

Patience my good man.
Nope no sign of them yet.

James
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matt211181

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Hi Meddo

The resistor is in the socket half of the brauduino cable.

I am reasonably sure that you could just use the harness with resistor in it and should work fine. Otherwise a socket can be bought on ebay or at Jaycar or similar and just wire that up. Just get the connections correct or the probe will die.

I think the hole was 10mm

I actually purchased a couple of the really small ones and will wire them up when they arrive.

James
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I'm looking to cut the existing temp sensor cable, and soldering the wires onto a new 3.5mm socket and jack (something like this: https://www.jaycar.com.au/3-5mm-stereo-line-socket/p/PS0134 and https://www.jaycar.com.au/3-5mm-stereo-plug/p/PP0130). This is so I can have a short cable length attached to the probe (attached to the kettle), so I can more easily disconnect the kettle from the controller (rather than fiddling around at the back of the controller), so I can take the kettle outside to clean etc.... (my controller isn't permanently mounted to the main vessel)

Zwitter - would you know the correct temp sensor wiring for the 3.5mm socket/jack?

Cheers!
Matt
 

zwitter

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Hi Matt 253525

Nah, can look it up but then if you have a spare you will have both parts anyway?

Red +5
Black Gnd
Yellow is data

As to which on which pin can not remember but as Imsay is probably on here in build threads or can just look at the one you have.

If you really get stuck I could go looking.
James
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Meddo

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Hey @zwitter, I'm just about to order a few of these displays now, plus a few extra probes so I can take readings at multiple points. Just wondering if the data line from these probes can be split so as to feed both my controller and a separate display from a single probe - any idea whether I can do this?

Cheers,
 

malt junkie

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They're one a one wire(data) BUS. Bus topology is the same as a road bus with the stops along the way being the one-wire devices. However they will to a degree work in star topology (where each device connects at a single point).
 

zwitter

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Hi Meddo

Interesting idea, never tried.
These temp sensors are really cool in their design. They are designed to have 3 wires positive supply, ground and data. That data line is multi drop so you can connect a couple of hundred sensors in parallel and they will all communicate with a unique id then data so you can tell them all apart. Brewpi uses this to connect 3 temp sensors but you can keep adding more.

I am thinking of adding a few extra temp probes to my matho system and the hardware is simple, just make a y connector and add an extra probe.

In fact these sensors can be used with 2 wires where the data line has power on it as well. Really versatile little things and cheap as well.

The problem in having two masters on the one sensor is that both would try to drive the data line and that would not really work. May blow various bits up. I do not think I would even try it. You can just put two temp sensors in same place. You could even make your own sensors with two of the little chips in the housing.

James
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