Can you read electronic schematics?

[bobsbeer]

If you can read schematics could you look at the diagram below. The bit I don't understand is the part enclosed in the box 'Not Populated'. The rest I understand but can't see how the enclosed bit relates to the circuit. It is part of the Brewtroller pressure/volume measuring circuit board. I am planning on putting it together myself, but see no point in adding extra circuitry that I don't need. The signal going to the arduino will come from JP2 or JP3 which are duplicated for some reason, but I plan on cutting JP2 out as well.



Below is what the actual board looks like.

 

[stevie1556]

I can read schematics, but can't work out what that box is for. C4 and C5 are in parallel so their values are added together for the total capacitance. Do you know what IC it is that is in that box? If you do, Google the datasheet then you should be able to work out what that section does.

Also, if you need a single sided circuit board, drop me a PM and I can do one for you. Also have a bunch of through hole and SMD components if you need any for it.

 

[KevinH]

I've just been on the website given on the pcb - oscsys.com and they have a forum and contact us - why not drop them a line? good luck.

 

[bobsbeer]

Thanks. At least I know it's not just me. That section does not seem to connect to anything. Which seems strange. Unless it was taken from a board that had some other purpose. The sensor itself also measures vacuum on the other port, but that isn't connected.

 

[anthonyUK]

Those capacitors are across a DC source so are probably just to keep the supply 'clean' by ensuring any AC interference is dropped to earth.
The two values will be for different frequencies.

The board shown is complete as per the diagram. Is this board what you have or are you going to make one from the individual components?

 

[bobsbeer]

I have checked with BrewTroller. The part in question is not needed but was put on the board in case other users used an outside 5v source, so it would clean up the noise. As the 5v source will come via the Arduino there is no need for it. So I have redrawn the schematic, which I will use to make my own board. I'm not sure I need the led but at least I know it's working.

 

[beermaker]

if it's for a 5V external source, it would either be a denoiser to clean up the power supply so it doesn't affect the signal from the sender unit to the receiver, or it could be a voltage regulator to ensure a stable and consistent voltage supply and prevent fluctuations and spikes. Judging by the number of pins on the IC I would hazard a guess at a denoiser, although hard to say for certain without knowing what the IC is.

 

[stevie1556]

For the LED, isn't it the wrong way round?
Personally, I would keep it in so you know it's switched on.

 

[bobsbeer]

Not sure about the LED. The LED diagram is how it was originally posted by brewtroller. The brewtroller board also uses the the board +5v so is not needed by them either, but it was put on the board to make it more versatile. They sell the made up board, so it makes sense to widen the appeal for other users.

 

[beermaker]

For the LED, isn't it the wrong way round?
Personally, I would keep it in so you know it's switched on.

well spotted that man! 330 Ohms is prob a bit high for a 5 volt supply - I use 330's on 9V supplies. For this, assuming your LED is drawing a current of approx 20 milliamps, you want something in the range of 100 to 170 ohm depending on the voltage required across the LED and the brightness you want. Err towards the higher end of the resistor values for longer LED life unless you want it really bright!

 

[bobsbeer]

I know when playing with my arduino blink sketch I used a 220 after the led and it was bright enough. So maybe I'll go with that. But I'm no electrician. :lol:

 

[beermaker]

220R would be a good preferred value for 5v :thumb:

 

[bobsbeer]

Changed. :thumb: Thanks for the heads up. I never noticed it was the wrong way round. And I have a few 220's