Connect 'Source' signal name to 'GND'

Question

Hello,

I need to attach the 'Source' on the this diode to GND without changing its name but Eagle will not allow me to do so. I've found older threads that mention creating a 'short' type part to do this.

But, I am wondering if this is made easier with newer version of Eagle? I'm a maker who has managed to create 2 PCB with Eagle that actually work, but still consider myself an extreme newbie.

Any guidance would be greatly appreciated.

Dave

autodeskguest · Answer

On 10/04/2018 12:25 a.m., dave hofer wrote: Hello, I need to attach the 'Source' on the this diode to GND without changing its name but Eagle will not allow me to do so. I've found older threads that mention creating a 'short' type part to do this. But, I am wondering if this is made easier with newer version of Eagle? I'm a maker who has managed to create 2 PCB with Eagle that actually work, but still consider myself an extreme newbie. Any guidance would be greatly appreciated. Dave -- To view any images and attachments in this post, visit: https://www.element14.com/community/message/238103 Hi Paul A few observations. If you wish to emulate the layout of the Electronics Hub circuit, then you have not achieved that. (1) You do not have a common point where the motor, diode and battery are connected together as there is in the Electronics Hub circuit. (2) Your image showing a motor and BAT1 3.7v has a problem. The diode is forward biased all the time so even if you remove the MOSFET, current will flow in the motor. (3) If you review the data sheet of the MOSFET you will see it has an internal diode that is in parallel with your discrete diode and oriented the same way so it would be doing a similar job. You could remove your discrete diode and still have the same circuit. As per the Electronics Hub circuit the diode needs to be across the motor and only the motor. So to keep the same board layout you would have to do the following. (a) remove the diode from the board as it is across the FET and it should be across the motor (b) Swap the wires going to J1 so the negative of the motor supply is on the round pad on the right and the motor negative is on the left square pad. (c) Mount the diode directly across the motor terminals with the anode to the negative terminal Also you need to achieve the equivalent of your white ground wire. What you need to do is common the negative of the motor supply with the ground of your arduino circuit. Assuming you have a schematic, change the name of the net attached to J1 pin 2 to GND. That will make the connection. This assumes your pull down resistor is connecting to a ground polygon in the area and that polygon encloses the pads currently connecting to the 'source' net which you have just renamed GND. HTH Warren -- ... use NNTP://news.cadsoft.de and a functional news reader like Thunderbird! --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

autodeskguest · Answer

On 09/04/18 16:01, dave hofer wrote: Werner, I've added a bit more detail from my board layout. Pin 9 is from an arduino pro mini (for reference) and all I am doing here is trigger a MOSFET. Since the device being turned on/off via the MOSFET could have an electric motor, I added the Diode to reduce the power feedback when the motor stopped. Without the diode, my arduino was resetting each time the motor was powered down (pin 9 pulled low). I also discovered that this would not work unless I also connected the anode side of the diode to ground. I do have a ground plane defined and it is named GND. The signal name for the Anode is 'SOURCE' and it's net class is '0 default.' I had a few of these built by Seeed Studio and they work fine when I solder a jumper wire from the Anode of the Diode to the GND pin of the pull down resistor. My challenge is replacing that jumper wire with GND connection to the anode of the diode. It would help if you could post the relevant part of your schematic and a note of your intended motor wiring. Based purely on what you have shown, the circuit doesn't appear to make sense. It looks like you've provided a connector to wire the motor across the FET, which won't work. Driving a DC motor (or other highly inductive load) is a very common task and there is a standard circuit for doing it. That circuit does include both a FET and a diode but not wired how you have. And as to the original question... if the net connected to the anode of the diode (and the source of the FET) is connected to ground then IT IS GND and you should let Eagle call it GND. Cheers, Rob