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Pwdr / Pwdr-Model-0.1

A powder substrate rapid prototyping machine
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Wrong connection in the circuit diagrams #17

Closed MatthiasWM closed 11 years ago

MatthiasWM commented 11 years ago

I think there is an error in the diagram. At the right side, the connection form pin 9 of both ULN2003 and the HP goes to the negative side of the cap (and, if you follow it further, to GND). If I read the diagram right, I beleive that this connection should actually go to the positive side of the cap, and hence +20V.

The ULN's can then pull the ink jets to GND, and the flyback diode inside the ULNs would work as expected. In the current setup, the ULNs would not do anything, or even cause a short.

Boreaz commented 11 years ago

Yes, the new scheme is wrong, and it have not digital disconnection with transistor, but it was in previous scheme. The 9 pins of ULNs must connect to output of LM317T. Additional in this scheme printhead connected wrong - 12 pin in U6 not connected, then 12 pin in U5 connected to wrong nozzle. It must be connected as in picture. Printhead Connection Proper I Think

And PwdrFirmware2_0.ino content some bugs, I'm not understand anything in programming, because of it I'm not shure -

  1. pushbutton and pull up transistor in firmware is 5(54 to abort print) and 14 pins, than in the scheme they are A0 and 21 pins.
  2. because of this - "if(upper_nozzles<<3 & mask){" signal in pin 30 is missing, it must be <<4.
  3. In firmware steppers connected to other pins than in scheme. And additional, pushbuttons A0 and RST must connect to GND, not to +5V

Ah, and I almost forgot, SD shield in scheme wired not right, I use this scheme with resistors http://arduino.cc/forum/index.php/topic,8314.0.html

Pwdr commented 11 years ago

Ill take a look on Monday, but it sounds pretty convincing. Mind that I did compose these drawings for publication after I build my machine. That is why the Arduino files don't match the diagrams.

On Friday, February 15, 2013, MatthiasWM wrote:

I think there is an error in the diagram. At the right side, the connection form pin 9 of both ULN2003 and the HP goes to the negative side of the cap (and, if you follow it further, to GND). If I read the diagram right, I beleive that this connection should actually go to the positive side of the cap, and hence +20V.

The ULN's can then pull the ink jets to GND, and the flyback diode inside the ULNs would work as expected. In the current setup, the ULNs would not do anything, or even cause a short.

— Reply to this email directly or view it on GitHubhttps://github.com/Pwdr/Pwdr-Model-0.1/issues/17.

MatthiasWM commented 11 years ago

Thanks for more clarity already.I know how difficult it is to document after the fact.